Adis, J., Max-Planck-Institute for Limnology, Tropical Ecology Working Group, Postfach l65, D-24302 Plön, Germany, Cokendolpher, J., 2007 29th St., Lubbock/Texas 79411, USA, Condé, B., Musée de Zoologie de l'Université et de la Ville de Nancy, 34, rue Sainte-Catherine, F-54000 Nancy, France, Reddell, J., Texas Memorial Museum, University of Texas, Austin/Texas 78705, USA, Scheller, U., Häggeboholm, Häggesled, S-53l94 Järpas, Sweden, Morais, J. W. de and Rodrigues, J. M. G., Instituto Nacional de Pesquisas da Amazônia (INPA), C.P. 478, 69.011-970 Manaus/AM, Brazil
Abundance and phenology of Palpigradi and Schizomida from Central Amazonian upland forests.
The 745 palpigrads (micro-whip scorpions) collected within 12 months in the soil (0-7 cm depth) of a primary upland forest (120.1 ± 50.8 ind./m2/month) and of a secondary upland forest (29.4 ± 20.2 ind./m2/month) near Manaus were represented by the species Eukoenenia janetscheki Condé 1993. About 75% of all specimens inhabited the mineral subsoil (3.5-7 cm depth) where monthly catches were negatively correlated with temperature and moisture content of the soil. Of the 547 schizomids (hubbardids) collected, Surazomus brasiliensis(Kraus 1967) represented 96% of the total catch in the primary forest (n=190; 37.5 ± 16.8 ind./m2/month), and Surazomus n.sp. amounted to 99.7% in the secondary forest (n=357; 60.4 ± 32.2 ind./m2 /month). About 70% of both species inhabited the organic soil layer (0-3.5 cm depth). Monthly catches of juveniles were correlated with temperatures of the soil, positively in S. brasiliensis and negatively in Surazomus n.sp. In the palpigrad and schizomid species, females were about twice as abundant as males. The lack of a distinct reproductive period and the presence of juveniles and adults (both sexes) throughout the year indicate a plurivoltine mode of life.
Adis, J., Max-Planck-Institute for Limnology, Tropical Ecology Working Group, Postfach l65, D-24302 Plön, Germany, Platnick, N. I., Dept. of Entomology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA, Messner, B., Zoological Institute, Ernst-Moritz-Arndt-University, J.-S. Bach-Str. 11/12, D-17489 Greifswald, Germany, Morais, J. W. de and Rodrigues, J. M. G., Instituto Nacional de Pesquisas da Amazônia (INPA), C.P. 478, 69.011-970 Manaus/AM, Brazil
Abundance and phenology of Ricinulei from Central Amazonian upland forests.
Ricinuleids collected within 12 months from primary and secondary upland forest soils (0-7 cm depth) near Manaus represented two species: (1) Cryptocellus becki Platnick & Shadab 1977 with 94 specimens, mostly juveniles, maximum abundance 38 ind./m2, and predominantly obtained during the season with less rainfall and (2) Cryptocellus adisi Platnick 1988 with 17 specimens, mostly juveniles, and up to 10 ind./m2. These sympatric species appear to be separated in their mutual habitat by spatial differences, with C. becki inhabiting mostly the organic soil layer and the smaller C. adisi the mineral subsoil. This is related to plastron retaining setae on the cuticular surface in C. adisi which are absent in C. becki. The lack of a distinct reproductive period and the presence of juveniles throughout the year indicate a plurivoltine mode of life in C. becki.
Aiken, M. and Coyle, F. A., Dept. of Biology, Western Carolina University, Cullowhee, NC 28723
Habitat distribution, life history and behavioral observations of Tetragnatha spider species in the Great Smoky Mountains National Park.
Habitat distribution patterns of five Tetragnatha species were studied by analyzing 1132 1-hr samples collected at 17 focal sites representing 16 major biotic communities (habitats) in the Great Smoky Mountains National Park. Tetragnatha versicolor is a habitat generalist, being common over a wide range of elevations (520-1755 m) and in 10 of the 16 habitats, including seven forest types, and wetland, high grass bald, and grassland habitats. Tetragnatha laboriosa is virtually restricted to non-wetland grassy habitats, T. elongata to streams, T. viridis to hemlock trees, and T. straminea to non-forested wetlands (marshes). Microhabitat segregation exists in the high grass bald community between T. versicolor (prefers trees and shrubs) and T. laboriosa (prefers herbs). Size frequency histograms of seasonal samples of T. straminea specimens indicate that this species has a one-year life cycle with six post-emergent instars, and that most individuals overwinter in the antepenultimate instar and mature and mate in May and June. Observations of T. straminea in nature and in the laboratory reveal that this species is able to capture prey with or without the use of a web.
Amaya, C. C., Dept. of Biology, University of Texas at Arlington, Arlington, TX 76019, Klawinski, P. D., Dept. of Biology, Shippensburg University, Shippensburg, PA 17257, and Formanowicz, Jr., D. R., Dept. of Biology, University of Texas at Arlington, Arlington, TX 16019
The effects of leg autotomy on running speed and foraging ability in two species of wolf spiders.
Spiders commonly autotomize legs as an effective means of escaping predation. Leg autotomy may affect sprint speed which might be important in foraging ability and escaping future predatory encounters. The effects of leg autotomy on running speed and foraging ability were examined in two species of wolf spider (Schizocosa ocreata & Varacosa sp.). Trials were run on spiders with all legs intact and then repeated after randomly autotomizing a leg from each spider. Results showed that both species exhibited slower running speeds following leg autotomy. However, foraging ability in both species was not affected by leg autotomy. The results from this study indicate that spiders may be susceptible to increased predation since spiders with one leg autotomized are slower than spiders with all legs intact.
Anderson, J. T., Dept. of Ecology and Evolutionary Biology, Brown University. Providence, R.I. 02912
Pick-up lines: how male Misumena vatia (Clerck) find reproductive females.
The low population density of the crab spider, Misumena vatia, and the high encounter rate of pregnant females in the field begs the question: how do adult males find reproductive females? I have explored only one of the tactics of adult males, namely their dragline following behavior. M. vatia individuals do not weave webs; however they do use dragline silk in their interplant movements. In both field and laboratory settings, adult males (but not juvenile males) crossed foreign draglines. Males do not respond chemically to these silk lines, but rather mechanically. In nature, they repetitively cross these lines, apparently in order to increase the probability of locating females. I discuss the ecological relevance of line-following in reference to other tactics males use to find females.
Arnedo, M. A. and Ribera, C., Departament de Biologia Animal, Universitat de Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain
Radiation of the genus Dysdera (Araneae, Dysderidae) in the Canary Islands: a cladistic assessment.
Oceanic islands biodiversity is the joint result of external colonization and local diversification. While in situ radiations have long been considered as the main causes for the generation of the biotas of Pacific archipelagos, like the Hawaiian Islands or Galapagos, the species inhabiting the volcanic islands of the Northeastern Atlantic, the so-called Macaronesian Archipelagos, have usually been interpreted as the relicts of past continental biotas or the result of chance characteristics of the original colonists of each species. The Canary Islands, 100 km off the Northwestern coast of Africa, harbor 43 endemic species of the mostly circum-Mediterranean spider genus Dysdera: about a quarter of its known species in an area that hardly represents 0.1% of its range. In order to assess the processes involved in the origin and formation of this extraordinary number of endemics, the phylogenetic relationships of these endemics and a sample of continental species (70 taxa) were recovered, based on a simultaneous cladistic analysis of 66 morphological characters, 471 pb of the COI and 424 pb of the 16SrRNA mitochondrial genes. Even though the preferred tree is ambiguous regarding the number of overseas colonizations, allowing a minimum of two and a maximum of four colonization events, it supports a single origin for most of the endemics (84%). Both interinsular colonizations and intrainsular radiations have played an important role in the diversification of this clade. The optimization of morphological characters hypothesized to be linked to prey preference, suggests the existence of ecological segregation in coexisting species and thus opens the possibility of the occurrence of sympatric speciation.
Aviles, L., Dept. of Ecology and Evolutionary Biology, University of Arizona, Tucson, Az 85721, and Gelsey, G., Dept. of Ecology and Evolutionary Biology, University of Arizona, Tucson, Az 85721
Natal dispersal and demography in Anelosimus jucundus and the transition to permanent-sociality in spiders.
The transition to permanent-sociality in spiders is thought to have involved the suppression of the dispersal phase characteristic of hypothetical subsocial or periodic-social ancestral species. Insights into this transition can be gained by studying dispersal patterns in extant periodic-social species in genera that contain the -social spiders. We found that Anelosimus jucundus (Araneae: Theridiidae) in Southern Arizona forms mother-offspring and sibling associations that disintegrate completely prior to the mating season. By periodically inspecting existing and newly established nests, we found that a significant fraction of spiders of both sexes became established within a few meters of the natal nest. As a result, sibmating apparently took place in at least two cases. Therefore, even though a fraction of the males apparently dispersed beyond the local area (as suggested by a 2:1 female per male ratio among newly founded nests, compared to a 1:1 ratio prior to dispersal) it appears that dispersal does not eliminate the possibility of close inbreeding in this species. Estimated transition probabilities between life history stages suggest that the heaviest loss of individuals occurs during dispersal. Once established, 41% of the females that reached maturity succeeded in producing grown progeny, with females that had managed to remain in or recolonize old nests having a higher probability of success than females that dispersed. We discuss the implications of these findings to the transition from periodic- to permanent-sociality in spiders and to current models that consider the interplay between competition and inbreeding avoidance in the evolution of dispersal.
Baehr, B., Zoologische Staatssammlung, Münchhausenstr 21, D-81247 München, Germany
Distribution pattern of the genus Asteron in tropical rainforests of Eastern Australia (Araneae, Zodariidae): long root combined with recent speciation
Recently, the first two species of the genus Asteron were described in the generic revision of the Zodariidae (Jocqué, 1991). In the meantime, no less than 80 species and more are recognized (Baehr & Jocqué, 1996). A well distinguished group (Asteron queenslandicum-group) of 21 species occurs in the tropical and subtropical rainforests of Queensland where they generally live in moss and litter on mountain tops above 900m. The Asteron queenslandicum-group is distributed throughout the Great Dividing Range over a distance of about 1500 km from the Queensland/New South Wales border in the south, to Mt. Finnigan south of Cooktown, in the north. But the rainforest patches themselves mostly occupy limited areas of only few square kilometers. Most species inhabit solitary mountain tops or tablelands, and only few species show a wide range or occur on two distant ranges. According to the patterns of distribution and to phylogenetic evidence the Asteron queenslandicum group probably belongs to the so-called "Old Gondwanan element" in Australia, because the genus Asteron as a whole is endemic to Australia. The high species diversity, however, may be a recent event: caused by the uplift of the Great Dividing Range during the Pliocene and Pleistocene and its subsequent disintegration into isolated tops and tablelands. Subsequently, the rainforests were separated in small patches as a consequence of the increasingly warmer and drier climate during the late Tertiary. The Asteron queenslandicum group is recommended as a good model to study recent speciation and vicariance biogeography.
Balfour, R. A.,Rypstra, A. L., and Marshall, S. D., Dept. of Zoology, Miami University, Oxford, OH 45056
The influence of intra and interspecific competition on two wolf spider species (Pardosa milvina and Hogna helluo).
When determining the competitive impact one species has on another, the size-structure of each species population is important. One would predict the opportunity of greatest competitive influence would occur when animals are of similar size. This study attempted to determine the competitive impact within and between two wolf spider species (Pardosa milvina and Hogna helluo) when they are of similar weight. Three 0.5 m2 enclosures were established within four 0.42 ha soybean plots. Each enclosure contained one of three treatments: 10 Pardosa, 10 Hogna, or 5 spiders of each species. Experimental runs lasted 5 days after which enclosures were searched and surviving spiders collected. Pardosa had a significantly (p=0.0016) higher mortality in the presence of Pardosa (30%) than when in the presence of Hogna (10 %). Although not significant (p--0.07), Hogna had a higher mortality in the presence of Pardosa (22%) than in the presence of otherHogna (15%). These data suggest that intraspecific interactions have a greater influence on Pardosa populations, and Pardosa may have an impact on co-occurring Hogna populations.
Bell, J. R., Gates, S., Haughton, A. J., Macdonald, D. W., Smith, H., Wildlife Conservation Research Unit, Dept. Zoology, Oxford University, South Parks Road, Oxford OX1 3PS, U.K., Wheater, C. P. and Cullen, W. R., Dept. of Environmental and Geographical Sciences, Manchester Metropolitan University, Manchester M1 5GD, U.K -->-->
Pseudoscorpions in field margins: effects of margin age, management and boundary habitats.
Pseudoscorpions are generally associated with deep leaf litter in deciduous woodlands. Few studies have examined them in grasslands despite some species occurring commonly in this ecosystem. Fewer still have considered the role of habitat management on pseudoscorpions in grassland margins. Pseudoscorpions (Chthonius ischnocheles (Hermann) and C. orthodactylus (Leach) sensu strictus) were collected using a D-Vac over two-years from 60 field margins at Oxford University farm at Wytham, U.K. Wytham is a substantial experiment of block design with replicated treatments to test for the effects of successional processes on specific invertebrate communities (e.g. spiders, butterflies and hemipteran bugs). In this study, old and new margins were subjected to six different treatments involving spraying, non-intervention and four different cutting intensities. The results showed clearly that significantly more pseudoscorpions were found in old compared to new margins, suggesting they may be attracted to litter build-up over time. Pseudoscorpion numbers were reduced on treatments subjected to two cuts annually, particularly when a summer cut was included, although this was ameliorated when the cuttings were left. However, pseudoscorpions were most numerous on treatments which involved no management because of the increase in leaf litter which may replicate a woodland environment. Adjacent hedges appear to buffer the effects of management: margins with adjacent hedges (rather than ditches or tracks) had more individuals. In contrast to results for other invertebrate groups, sowing wildflower seed did not significantly increase the abundance of pseudoscorpions. The effect of different treatments on pseudoscorpion numbers demonstrate that they are useful indicators of the effects of management practice.
Bergthaler, G. J., University of Salzburg, Institute of Zoology, Hellbrunner Str. 34, 5020 Salzburg, Austria
A suction sampler study of arachnid densities in newly planted hedges and adjacent agricultural land .
A petrol driven hand-held machine, normally used to collect leaf litter, was modified to be used as a suction sampler for arachnids in newly planted hedges and adjacent agricultural land. Altogether 2073 specimens - 1769 spiders, 304 harvestmen - were collected during seven sampling procedures between the beginning of June and the end of September 1997. Preliminary results of a long-term study which is being continued show significant differences in the species composition of the communities as well as in the densities of spiders and harvestmen between each of the 7 sites: 2 hedgerows, 1 copse, 2 maize fields, and 1 grassland. The numbers of specimens of every arachnid family as well as of every species and its sex were calculated for each sampling procedure and site. It resulted in smaller numbers of species and specimens in the agricultural sites, to the contrary of the results in the hedgerows as well as in the copse. The highest arachnid density was reached at the beginning of autumn in one of the hedgerows with 38 specimens per 0.1 m².
Bilde, T. andToft, S., Dept. of Zoology, University of Aarhus, Building 135, DK-8000 Arhus C, Denmark
Value of cereal aphids as food for the linyphiid spider Erigone atra.
The objective of this study was to evaluate the quality of three species of cereal aphids as food for a generalist predator, Erigone atra, which is com-mon in arable land and is a natural enemy of aphids. This was done by means of egg production and development experiments. The aphid species used in the experiments were Metopolophium dirhodum, Sitobion avenae and Rhopalosiphum padi; fruit flies Drosophila melanogaster were used as control prey in the egg production experiment. Females of E. atra were collected in the field and standardized on a diet of fruit flies. After having produced one egg sac, they were randomly assigned to one of 8 diet treat-ments: M. dirhodum; S. avenae; R. padi; D. melanogaster + M. dirhodum; D. melanogaster + S.avenae; D. melanogaster + R. padi; M. dirhodum + S. avenae + R. padi; D. melanogaster. The following parameters were recorded: no. of egg sacs, no. of eggs/sac, hatching success, size of young. In all aphid treatments including the mixed aphid diet females stopped egg laying after approximately 3 egg sacs, while they continued producing egg sacs in all D. melanogaster treatments. In the development experiment E. atra females were fed fruit flies, and young from the first egg sac were used. In this experiment the collembola Isotoma tigrina was included as prey. Hatchlings were assigned to one of 5 diet treatments: M. dirhodum; S. avenae; R. padi; L tigrina; starvation. Molts and survival time were recorded. Of the three aphid treatments M. dirhodum supported the highest proportion of spiders reaching the first molt and the longest survival time.
Binford, G. B., Dept. of Ecology and Evolutionary Biology, University of Arizona, Tucson
Diversification of spider venom: an analysis of interpopulational venom differences in Tegenaria agrestis (Agelenidae).
Chemical composition of venom varies substantially among spider taxa and there is evidence of variation within species. Yet, patterns of variation in venom have not been well described. Here I present results of comparative analyses of venom from populations of Tegenaria agrestis, a species with evidence of interpopulational differences in venom pharmacology. T. agrestis is common and widespread throughout central Europe and was introduced into the Pacific Northwest region of the United States early this century. Recently in the Pacific Northwest T. agrestisbites have been reported to result in necrotic lesions in humans, an effect never before reported in Europe. I characterized venom composition of T. agrestis populations from Seattle, Salt Lake City, and England using liquid chromatography (RP-HPLC). Comparisons of the chromatographic profiles indicate subtle, but not striking differences in venom chemistry between these populations. Females from the US populations are more similar to each other than either are to the England population. Also, there are detectable, but fewer, differences between Seattle and Salt Lake City populations. Venom of males from England and Salt Lake City are distinctly different from female venom and are more similar to each other than either are to females from their own populations. Bioassays are underway to determine whether differences in the physiological effect can be consistently detected and correlated with differences between the HPLC profiles. If a difference in venom effect is detectable, this may provide an example of a recent evolutionary change in venom associated with a range expansion event.
Bjørn, Per de Place, Entomological Dept., Zoological Museum, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen
Phylogeny of the East African erigonine genus Ophrynia (Araneae: Linyphiidae).
The erigonine fauna of the montane East African biota is fairly well known, and during the last 40 years numerous species have been described. The phylogeny and biogeography of these taxa is, however, nearly unresolved. An attempt to reconstruct the species level phylogeny of the genus Ophrynia- endemic to the Eastern Arc Mountains in Tanzania - was made. For assignment of outgroups and for character polarisation, the representatives of the genera Ophrynia, Callitrichiaand Elgonia were added to a large character matrix, designed for investigation of erigonine relationships (Hormiga, in press). Subsequently all known species of Ophrynia- including 2 undescribed species, and 3 outgroup taxa were scored for 90 characters, pertaining to chaetotaxi, genitalia anatomy, and carapace morphology, including eye arrangements. The data were analyzed with both equally, and successively weighted characters, using a variety of parsimony computer programs.
Blackledge, T. A., Dept. of Entomology, Ohio State University, Columbus, OH 43210
Stabilimenta and predator-prey tradeoffs in Argiope.
Variation in stabilimentum size and frequency in webs indicates that tradeoffs are made by Argiopespp. between the costs and benefits of these enigmatic structures. Stabilimenta can warn predators of the presence of a noxious web, preventing damage to webs and spiders. Yet, webs of Argiope aurantia containing stabilimenta catch up to 30% fewer prey than do webs with stabilimenta removed. Thus, the ability of insect prey to use stabilimenta as a visual signal in avoidance of webs has likely been an importance selective factor in their evolution. The derived white+UV reflective silk in stabilimenta appears to be poorly differentiated from environmental noise by many pollinating insects. I suggest that, while maintaining visibility to vertebrate predators, the reflectance spectrum of stabilimentum silk may have evolved to render stabilimenta less visible to insect prey, reducing the negative impact of stabilimenta on prey capture.
Blick, T., Arachnologische Gesellschaft, Heidloh 8, D-95503 Hummeltal, Germany
Aspects of succession of epigeic spiders at managed forest borders in southern Germany.
Ground layer spiders at managed and unchanged forest borders in central southern Germany have been investigated. In Germany the landscape is strongly influenced by men. Usually there is a sharp border between meadows or arable land and the forests. Borders with a zone of transition between forest and open land are rare. Vegetation management procedures were used to increase the structural complexity on the borders of forests which were initially of low complexity (project supported by the German Ministry of the Environment): planting shrubs and small trees outside the former border, a new stripe of fallow land (herbaceous stripe), partly cutting of "economic" forest trees (pines and spruce) and planting of broadleaf trees. The spiders have been caught by pitfall-trapping in different rows (each 6 traps) at several forest borders, mainly 12 month every year from 1989 until now. The succession of the spider fauna at managed borders and the herbaceous stripes is compared with unchanged borders. After 7 years the development of the fauna is clearly directed to natural forest borders, but they will reach a natural stage earliest after 15 to 20 years. Different typical patterns of single spider species can be stated: going down in the first years, peaks of different species in every year until now, still increasing species and species which could not settle in the managed area. There is no typical species for forest borders, but few species thought to be very rare before. The speed of development can be increased slightly by managing.
Bodner, G. S., Dept. of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, Coddington, J. A., Dept. of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, and Edwards, G. B., Florida State Collection of Arthropods, Division of Plant Industry, P.O. Box 147100, Gainesville, FL 32614-7100
Biodiversity assessment and habitat specificity of neotropical salticids.
An intensive survey of jumping spiders (Araneae: Salticidae) was conducted at the La Selva Biological Station in central Costa Rica between September 1996 and January 1997. Structured collecting was done by four Costa Rican para-taxonomists, with additional collecting by three experienced arachnologists. The sampling was done according to a nested design, targeting three sites, three habitats per site, and three collecting methods per habitat, with a total of over 650 person hours. We also used samples from the canopies of eighteen trees, collected in 1993 and 1994 by insecticidal fogging. We found a total of approximately one hundred salticid species, with only eleven singletons. Habitats differed considerably in salticid abundance, diversity, and species composition. Salticid groups showed varying degrees of habitat specificity. The genus Corythalia, for example, shows evidence for elaborate niche partitioning in all habitats, while members of the Amycine subfamily are rarely found in the early successional habitats. In this study, I examine both habitat specificity and the relative efficiency of collecting in different habitats, and address implications for less intensive surveys.
HPBond, J. E. and Opell, B. D., Dept. of Biology, Virginia Polytechnic Institute and State University. Blacksburg, VA 24061
Phylogeny of the Rastelloidina and the monophyly of the Cyrtaucheniidae (Araneae, Mygalomorphae).
Raven's 1985 classification of the spider infraorder Mygalomorphae established the new Gigapicoorder Rastelloidina which included the families Cyrtaucheniidae, Idiopidae, Ctenizidae, Actinopodidae, and Migidae. This familial composition of rastelloids was supported by Goloboff's 1993 reanalysis of mygalomorph relationships. However, he suggested that the family Cyrtaucheniidae is polyphyletic but considered his sampling of genera insufficient to warrant nomenclatural changes. This study attempts to resolve the relationships of the cyrtaucheniid genera within the context of the Rastelloidina and thus clarify questions regarding the monophyly of the family raised by both Raven and Goloboff. A phylogeny of 16 genera of cyrtuacheniids plus eight genera from four related families based on 68 morphological characters shows convincingly that Cyrtuacheniidae is polyphyletic. This analysis necessitates substantial change in rastelloid classification and suggests the establishment of at least two new families. One newly proposed family includes the genera Kiama, Fufius, Rhytidicolus, Acontius,Ancylotrypa, Bolostromos, and Bolostromoides. The North American Eucteinizinae plus the South African genus Homostola form another monophyletic group that must likewise be recognized as a new family. Additionally, three new genera are proposed for the North American clade. In addition to the morphological analysis of rastelloid genera, 650 base pairs of the nuclear 28s ribosomal DNA and 450 base pairs of the mitochondrial 16s ribosomal for 17 taxa are used to resolve relationships of the North American euctenizid genera. The molecular data set corroborates both the euctenizid relationships and the suspected polyphyly of the genus Aptostichus indicated by the morphological data set.
Bosselaers, Jan, "Dochterland", R. novarumlaan 2, B-2340 Beerse, Belgium, and Jocqué, Rudy, Invertebrate section, Royal Museum for Central Africa, B-3080 Tervuren, Belgium
Funny eyes, basket legs or garden legs: a huge new genus of tiny Afrotropical Liocranidae (Araneae).
A new genus of small (1.5-4mm), pale, soil-dwelling spiders is described on material from tropical Africa. The genus is characterized by the presence of a peculiar ellipsoidal array of setae on the dorsal side of metatarsi I and II and by the large AME with a dark tapetum restricted to the median portion. The genus is tentatively placed in the Liocranidae. So far it contains 65 species, all of which are new. It thus becomes the largest genus in the Liocranidae and one of the largest genera of African spiders. The genus has a vast Afrotropical distribution, occurring from as far south as East London in South Africa to Sierra Leone in western Africa. So far, no specimens are available from north-eastern tropical Africa. Apart from a particular South African species, which seems to prefer grassland, all species are found in leaf litter of different kinds of forests and dense thickets. A cladistic analysis mainly based on secondary genital characters is proposed. Two cladograms are presented: one is only based on species for which both sexes are know, the second includes all known 65 species.
Bradley, R., Dept. of Zoology, The Ohio State University, 1465 Mt. Vernon Ave., Marion OH 43302
A comparison of spider species diversity in the soil/litter stratum and the understory vegetation of four selected forest sites in Ohio.
This study is part of a larger effort to determine the species diversity, distribution and abundance patterns of spiders in Ohio funded by the Ohio Division of Wildlife. Spider communities were sampled at Conkle's Hollow Natural Area (Hocking Co.), Glen Helen Outdoor Education Center (Greene Co.), Fowler woods Natural Area (Richland Co.), Seymour Woods Natural Area (Delaware Co.) between May 1994 and October 1997. Sampling methods included visual search, beating sheet, sweep net, pitfall trap, and litter extraction. The species diversity index for the soil/litter stratum was lower than for the understory vegetation at each site. Each sampling method captured a number of species not represented in other samples; 45% of species were captured by only one method and an additional 35% of species were captured by only two of the five methods. Visual search at ground level, litter extraction and pitfall traps captured a higher proportion of unique species than the other sampling methods. Despite a considerable sampling effort to date, species-accumulation plots indicate that many species remain to be documented from each of the study sites.
Brady, A. R., Dept. of Biology, Hope College, Holland, MI 49423
Sosippus revisited (Araneae: Lycosidae).
Sosippus was placed in the Subfamily Hippasinae by Roewer (1954). A comparison of Sosippus to other species of Hippasinae revealed little similarity in diagnostic features (Brady, l962). Additional information lends little credence to any close phylogenetic relationship between Sosippus and the other Hippasinae. Species of Sosippus are the only North American species of Lycosidae that construct a sheet web with funnel-shaped retreat. Male palpal characters led Dondale (1986) to place Sosippus in the new subfamily Sosippinae. These features suggest thatSosippus may be among the most primitive group of lycosid species. Field studies (Brady, 1972) allowed recognition of two new species: S. janus and S. placidus, and it was shown that the distribution pattern of Sosippus in Florida conformed to islands that existed during the Pleistocene. The primary events influencing this pattern were: (1) water gaps producing barriers to gene flow, and (2) small island populations that were subject to genetic revolutions. Recent laboratory observations indicate that subsocial behavior in Sosippus janus may result in limited dispersal of this species, thus contributing to the present insular distribution pattern of Sosippusspecies in Florida.
Brookhart, J. O., 7393 S. Tamarac St., Englewood, CO 80112 and Brantley, S. L., Dept. of Biology, University of New Mexico, Albuquerque, NM 87131
Solpugids of the Sevilleta NWR: regional influences on species composition.
The Sevilleta NWR, an LTER site in central New Mexico, is a large area at the intersection of several vegetation biomes. Species richness at these intersections is hypothesized to be higher than in the centers of species ranges. In this paper we will compare solpugid species richness at the Sevilleta NWR with other locations and examine regional influences on species composition. Solpugids have been collected by pitfall trapping since 1989 as part of the ongoing monitoring of arthropod populations at the Sevilleta NWR. Twelve species are now known from the site, including a new species in the genus Hemerotrecha, and a state record for Eremobates simoni. Eremobates pallipes and Hemerotrecha fruitanawere common and widespread. There was some evidence of hybridization between E. pallipes and E. arizonica, although none between the two sympatric species of Arenotherus, A. puebloensis and A. mumai. Biogeographic influences on species composition included the Great Plains, Rocky Mountains, Rio Grande Basin and Chihuahuan Desert. Sevilleta species richness and composition were similar to those of Colorado. Two species, known previously from more southerly locations, may also be indicators of desertification of the area.
Brown, Christopher A., Dept. of Biology, Box 19498, University of Texas of Arlington, Arlington, TX 76019
Geographic and temporal patterns of variation in reproductive investment in the scorpion Centruroides vittatus.
Life histories play a central role in attempts to explain the origins of diversity of living organisms, since differences among individuals in life history traits lead to variation in fitness and, hence, to natural selection. Many life history studies therefore focus on understanding the extent and causes of intra- or interspecific variation in life history patterns. For this study, I examined variation in reproductive investment patterns in Centruroides vittatus from three Texas populations [Decatur, Kickapoo, and Independence Creek (IC)] over a four year period (1992-5). Significant among population differences in almost all variables were found during each year, with the direction of these differences generally constant across years. Kickapoo females were always largest and produced the largest, heaviest litters, followed in rank by IC and then Decatur. Kickapoo offspring were smaller than IC offspring in all years and than Decatur offspring during all but 1995. During 1993 litters from IC and Kickapoo were significantly smaller and lighter, and offspring were smaller and varied in size more within a litter, than during the remaining three years. Within a population, heavier litters generally, but not always, contained both more and larger offspring. There was little evidence for an offspring size-number trade-off. Larger females generally produced larger and heavier litters, but there was no relationship between female size and offspring size. These differences may represent a combination of environmental and genetic factors which vary among populations.
Buddle, C. M., Dept. of Biological Science, University of Alberta. Edmonton, Alberta T6G 2E9
The succession of boreal forest spiders in stands originating from clear-cuts and wildfires.
Harvesting has largely replaced wildfire as the main stand regenerator for aspen-dominated forests in north-central Alberta. Extensive harvesting regimes may have detrimental consequences for the long term sustainability and productivity of these forests. Spiders were used to assess the recovery of aspen stands to disturbance by harvesting compared to the natural course of succession following wildfire. The spider fauna from stands originating in wildfire is compared to the community in stands originating from clear-cuts from 1, 14 and 28 year-old stands. Ground dwelling species were sampled using pitfall traps during the snow-free seasons of 1996 and 1997. Species living in the understorey vegetation were sampled in 1997 using a sweep-net. A total of 136 species from 15 families and over 7600 specimens were identified from two years of sampling. The spider fauna from recently burned stands is distinct from the fauna in young clear-cut stands. There is a clear succession in the community from young stands dominated by lycosid spiders to 28 year-old stand dominated by linyphiid spiders. Although spider assemblages are similar after 28 years of forest growth following wildfire and harvest, the trajectories in recolonization appear dependent on disturbance type.
Cangialosi, K. R., Dept. of Biology, Keene State College, Keene, NH 03435-2001
The relative importance of developmental status versus size in affecting the foraging mode of Argyrodes trigonum.
Previous work has shown that the foraging strategy of Argyrodes trigonum is influenced by a variety of environmental factors including host species and prey availability. Although field surveys suggest that the developmental stage of A. trigonum also plays a role in determining which foraging mode is exhibited, it is possible that any differences in foraging may merely be the result of differences in the size of the host spider relative to A. trigonum. In this study, I performed laboratory tests in order to separate potential ontogenetic changes in foraging behavior from absolute size differences. In the first experiment, the host/Argyrodessize ratio was held constant while the size of A. trigonum was varied. In the second experiment, the size of A. trigonum was held constant while the host/Argyrodes size ratio was varied. Spiders were kept in ten gallon aquaria each containing a single host spider, Achaearanea tepidariorum, and an A. trigonum individual. Observations of positions and interactions between A. trigonum and its host were recorded every 24 hrs. for 7 days. Later developmental stages of A. trigonum exhibit more aggressive foraging tactics such as web stealing and host predation regardless of the relative size of the host. This suggests that there is a developmental program causing these spiders to shift to more aggressive foraging modes as they mature, perhaps due to increased energetic requirements.
Carlson, Robin L. andGriswold, Charles, E., Dept. of Entomology, California Academy of Sciences, San Francisco, CA 94118
Ontogeny of the spinning organs of Phyxelida tanganensis.
The postembryonic changes in the entire spinning field of a cribellate spider, Phyxelida tanganensis, were observed in order to gain insight into the development and function of the silk spigots. Juveniles of each instar after emergence from the eggsac were preserved, and their spinning complements observed using the scanning electron microscope. The timing of appearance of each type of spigot was analyzed in relation to its function.
Catley, K. M., Dept. of Entomology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024
The gnaphosid genus Encoptarthriain Australia - work in progress.
The genus Encoptarthriawas established in 1954 by Main for Encoptarthria serventyi from Western Australia; it remains monotypic. This paper describes systematic work in progress on this genus as part of a larger collaborative study of the gnaphosoids of Australia. Examination of large collections from Australian museums as well as material collected in the field shows that the genus has in fact undergone a huge radiation. Ultimately it is expected the taxon will represent a monophyletic group of perhaps 100 species or so, comprising several genera. Characters which diagnose and support the putative monophyly of the taxon are presented, as are characters diagnostic at the generic level. The synonymy of Megamyrmaekion species described from Western Australia by Simon in 1908 with Encoptarthria is also discussed. The taxon is known from every State in Australia, and although it has been collected from a variety of habitats including rainforest, it appears to have undergone its major radiation in arid regions.
Chen, Jun, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China, and Song Daxiang, Dept. of Biology, Hebei Normal University, Shijiazhuang 050016, P. R. China
Notes on zoogeographic divisions of Chinese wolf spiders (Araneae, Lycosidae).
Based on the distribution of 200 species of Chinese wolf spiders, the component similarities of lycosids in 17 subregions of the seven Chinese zoogeographic regions are discussed through hierarchical cluster analysis. The result shows that the division of four zoogeographic regions, i. e. Northeast China Region, North China Region, Central China Region and South China Region, of the seven regions is coincident with the distribution pattern of Chinese wolf spiders. But the Eastern Prairie Subregion of Inner Mongolia-Xinjiang Region and the Southwest Mountain Subregion of Southwest China Region cannot be clustered well. After further dividing the Southwest Mountain Subregion into two parts as Southwest High Mountain Subregion and Southwest Low Mountain Subregion along the line through Qionglaishan Mountain (31.1°N, 102.7°E), Daduhe River (29.9°N, 102.2°E), Xichang (27.9°N, 102.2°E), Yanyuan (27.4°N, 101.4°E), Lijiang (26.8°N, 100.2°E), Lanping (26.4°N, 99.2°E), Lushui (25.9°N, 98.8°E), a better result in clustering is obtained and it shows that Southwest Low Mountain Subregion should not be placed in Southwest China Region. Another result shows that the lycosid components of Qinghai-Xizang Plateau are obviously different from those of other areas. It includes many endemic species (33 spp.), neither Palearctic components nor Oriental ones, counting for 51.6% of the total number of species (64 spp.) of that region. Comparisons of component similarities of wolf spiders among Korea, Japan and zoogeographic regions of China are also made in this paper.
Churchill, Tracey, Tropical Savannas Co-operative Research Centre CSIRO Wildlife and Ecology, PMB 44 Winnellie, Northern Territory, Australia 0822
Differential selection of habitat patches by an Australian tropical lycosid.
The wolf spider species Lycosa laeta occurs in sclerophyll forests of Australia's monsoonal tropics. In the field, environmental variables were quantified to identify those most associated with high lycosid abundance. For each variable selected (grass density, leaf litter, soil moisture and soil temperature), a range of options were provided in laboratory choice experiments to investigate the role of habitat selection in determining distribution patterns. Selective responses to these options varied across three size classes of lycosids. Juveniles preferred sparse grass, leaf litter patches, lower temperatures and moderate to high soil moisture. In contrast, adults preferred the edges of dense grass, bare ground rather than litter, higher temperatures, and drier soil conditions. Experimental results were consistent with the field observations, which revealed that spatial separation of size classes was augmented on a temporal scale. Consequently, the differential use of microhabitats was related to changing microclimatic requirements with maturity, as well as reducing the probability of cannibalistic attack from conspecifics. Overall, results suggest that habitat selection was an adequate explanation of the local distribution patterns exhibited by this species, and that there was no need to invoke a role for interspecific competition.
Coddington, J. A., Dept. of Entomology, National Museum of Natural History, NHB-105, Smithsonian Institution, Washington, D.C. 20560, and Scharff, N., Zoologisk Museum, Universitetsparken 15, DK-2100 København, Denmark
Progress in araneoid systematics (Araneae, Araneoidea).
Two recently completed phylogenetic analyses on 89 araneoid genera including all families for the first time specify unambiguously the relationships of major araneoid lineages. This result permits phylogenetically consistent hypotheses on classic evolutionary phenomena in spiders: spinning organs, the stabilimentum, the orbweb and other web architectures, male genitalia, and sexual size dimorphism. The evolution of the spinning field apparently proceeded mainly through reduction, simplification, and specialization within fields containing multiple spigots of the same gland type. Web decorations like the stabilimentum have evolved numerous times, and, presumably, for various reasons. Evolutionary speculations about stabilimenta need to be reformed in light of this fact. Web decorations require batteries of spigots, lost among distal araneoids. Distal araneoids, therefore, should not be able to decorate their webs, or should have more difficulty in doing so. These results also portray a coherent scenario for orb-web evolution. The orbweb originated from cribellate "sheetwebs" which exhibit many of the regular features typical of orbwebs. All orbwebs are homologous as orbwebs, but the plesiomorphic architecture has been highly modified in many lineages. The results predict that theridiid, cyatholipoid, and linyphioid sheets are homologous as sheets rather than independent losses of the orb. Sexual size dimorphism is shown to be a complex topic with, in theory, at least nine different possible evolutionary pathways, all of which may occur among orbicularian spiders. The male "embolus cap," allegedly due exclusively to sexual selection, is tested for correlated change with sexual size dimorphism.
Craig, C. L., Museum of Comparative Zoology, 26 Oxford Street, Harvard Unversity, Cambridge, MA 02138
The effects of diet on the amino acid composition of silks.
Molecular sequence and gene regulation are studied intensively to elucidate the evolution of proteins. Less frequently considered, and more difficult to quantify, is if and how the ecological environment in which an organism evolves can bias gene expression and hence protein evolution. Almost all proteins are produced by the organisms that use them and protein baseline costs are equal to the synthetic costs of their component amino acids. Therefore, if proteins are highly expressed, such as the silks spun by insects and spiders, one might predict selection for component amino-acids that are metabolically inexpensive. However, if composed of amino acids that are metabolically costly, selection for reduced protein costs may be limited by functional or ecological constraint. Across taxa comparison of silk synthetic costs shows that those produced by ancestral species and in ancestral silk producing glands can be characterized as metabolically cheap, while those produced by derived species and in more recently evolved glands, are metabolically expensive and may be evolving under structural constraint. Nevertheless, within species comparison of dragline silk produced by A. argentata shows that silk composition (and hence their metabolic costs) can also vary significantly across spider foraging habitats suggesting that local variation in available prey may be able to affect silk functional properties.
Croucamp, W. and Veale, R., Dept. of Zoology, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa
Monitoring the cytotoxic effects of spider venom in vitro.
Annually, sac spiders of the genus Cheiracanthium are responsible for a large number of human envenomations. Cheiracanthium furculatum causes the majority of these envenomations which result in significant cytotoxic lesions, necessitating the study of its venom, and the development of a rapid and reproducible method of monitoring cytotoxicity. Preliminary analyses show the venom of male spiders to contain 61.1 ug/ml protein and those of female spiders 55.2 ug/ml protein. Also, the venom exhibits proteolytic activity with protein concentrations as low as 2.0 units x 10-3/ug of venom protein. The use of animal models for toxicity testing is both cumbersome and open to criticism on ethical grounds. Here we describe an in vitro method employing human cell lines to evaluate the effects of cytotoxic spider venoms. Fresh venom was obtained by electrical stimulation and stored in PBS at -70 °C. Human carcinoma cell lines, cultured under standard sterile conditions in multi-well plates, were exposed to serial dilutions of venom. Changes such as granulation, rounding-up and detachment were recorded over time. Cells exposed to low venom concentrations containing as little as 5.0 ng/ml protein became granular after 5 minutes, rounded-up after 20 minutes and detached after 30 minutes. At high venom concentrations of 32.0 ng/ml protein the cells became granular almost instantly, started to round-up and detached after only 15 minutes. Although full-thickness mouse skin has been used in tissue culture to show the extent of cytotoxicity, this system provides a simple, rapid, accurate and reproducible measure of cytotoxic effect.
Crouch, Tanza E., Durban Natural Science Museum, P.O. Box 4085, Durban 4000, South Africa, and Lubin, Yael D., Blaustein Institute for Desert Research, Ben Gurion University, Sede Boqer Campus, 84990 Israel.
Mechanisms of colony expansion and contraction in the social spider Stegodyphus mimosarum(Araneae: Eresidae).
Social spiders are known to be distributed patchily in their natural habitats. However, long-term data on the dynamics of colony and population change are generally lacking and the mechanisms of population expansion and decline are poorly understood. We monitored more than 550 nests of Stegodyphus mimosarum Pavesi, 1883 which were established on the railing of the Mkomazi River bridge, KwaZulu-Natal, South Africa. Colonies were inspected at monthly intervals from September 1994 to April 1998 in order to identify periods of change in the number and sizes of nests within the population. We also monitored the abiotic (temperature and rainfall) and biotic conditions (parasitism and prey availability) to which these colonies were exposed. These data were used to examine the hypothesis that biotic and abiotic conditions explain the variability observed in colony dynamics. Results showed that dispersal followed a period of decline in total nest numbers. With the exception of the year of dispersal (1997), annual increases in numbers of old nests (i.e. population contraction) coincided with periods when spiders were juvenile. Colony expansion took place twice to three times annually when spiders were large juveniles or subadults. Although colony expansion was greatest following dispersal in December 1997, current nest numbers have declined by half. Neither climatic conditions nor prey availability and parasitism correlated significantly with total nest numbers, the occurrence of new nests and changes in nest size during the study period. Nonetheless, parasitism may have an important consequences for colony survival in the long-term. During a single day in November 1996 an estimated 0.14% of the population was parasitized. At this level of parasitism more than 4% mortality would occur during this month alone. This raises the question of the importance of predation and parasitism in driving sociality.
Davies, V. Todd, Queensland Museum, Brisbane, Australia 4101
A new spider genus from North Queensland, Australia (Araneae: Amaurobioidea: Kababininae).
The description and diagnosis of a new amaurobioid genus allows one to relate it to described genera and to contribute characters for the phylogenetic analysis of the superfamily. The genus described here is from rainforest in the Wet Tropics region of North Queensland which is recognized as an area of high specific diversity. The genus is characterized by the extraordinarily elaborate embolic apophyses; four new species are described. Cladistic analysis suggests that the Australian arnaurobioids fall into two clades: the first includes the Desidae and the Amphinectidae; the second includes the Amaurobiidae, Stiphidiidae, Metalltellinae and Kababininae. The new genus and Kababina Davies 1995 form a well supported monophyletic group, Kababininae. This provides evidence that the group does not belong in the Amphinectidae as previously suggested; its placement in a family remains problematical.
Davis, M. J. and Coyle, F. A., Dept. of Biology, Western Carolina University, Cullowhee, NC 28723
Habitat distribution and life history of Araneus spider species in the Great Smoky Mountains National Park.
Habitat distribution patterns of nine Araneus species were studied by analyzing 1132 1-hr samples from 17 focal sites representing 16 major biotic communities (habitats) in the Great Smoky Mountains National Park. Of the five (large-bodied) diadematus group species, A. nordmanniis common or abundant in 12 of the 16 habitats (ten forest types, heath bald, and high grass bald), A. marmoreusis common or abundant in five habitats (four forest types and high grass bald),A. trifolium is restricted to grass balds, and A. bicentenariusand A. iviei are virtually restricted to (and uncommon in) forest edge and marsh habitats, respectively. In the three forest communities (red oak, northern hardwood, and beech gap) where A. nordmanni and A. marmoreus coexist in high densities, microhabitat segregation exists, at least in the adult stage; nordmanni females use only trees as retreat/web substrates and marmoreus females use only the herbaceous vegetation of tree gaps. Of the small-bodied Araneusspecies (A. cingulatus, A. miniatus, A. pegnia, and A. pratensis), only the latter, which is restricted to grassland, appears to be common or abundant in any habitat. Size frequency histograms of seasonal samples of A. nordmannispecimens indicate that this species has a two-year life cycle with eight post-emergent instars. Spiderlings emerge from the egg sac in the spring and develop to post-emergent instar IV, V, or VI before overwintering. During late summer of the second year, these spiders reach adulthood and reproduce.
Deltshev, C., Institute of Zoology, Bulgarian Academy of Sciences, bld. Tsar Osvoboditel 1, 1000-Sofia, Bulgaria
A faunistic and zoogeographical review of the spiders (Araneae) in the Balkan peninsula.
The spiders (Araneae) are represented in the Balkan Peninsula by 1411 species, included in 47 families (Atypidae 2, Ctenizidae 6, Nemesidae 7, Filistatidae 3, Sicaridae 1, Scytodidae 1, Pholcidae 16, Leptonetidae 18, Segestridae 5, Dysderidae 106, Oonopidae 5, Palpimanidae 1, Mimetidae 5, Eresidae 3, Oecobiidae 4, Uloboridae 6, Nesticidae, 9, Theridiidae 91, Theridiosomatidae 1, Anapidae 2, Mysmenidae 1, Linyphiidae 330, Tetragnathidae 26, Araneidae 55, Lycosidae 83, Pisauridae 3, Oxyopidae 3, Zoropsidae 2, Agelenidae 64, Cybaeidae 4, Argyronetidae 1, Desidae 1, Hahnidae 12, Dictynidae 23, Amaurobiidae 37, Titanoecidae 6, Anyphenidae 2, Liocranidae 19, Clubionidae 36, Corinnidae 3, Zodariidae 23, Prodidomidae 2, Gnaphosidae 131, Zoridae 10, Heteropodidae 5, Philodromidae 37, Thomisidae 70, Salticidae 130). This number was established after a critical review of existing information on available collections containing spider material from the Balkan Peninsula. Countries with the highest number of recorded species are Bulgaria (775), Greece (642), Croatia (615) and Serbia (508). According to their distribution the 1411 species can be classified in 24 zoogeograpical categories, grouped into 4 complexes (Widely distributed, European, Balkan endemics and Mediterranean). Widely distributed species are dominant, but Balkan endemics are the most characteristic. The established number (379) is high and reflect the local character of the fauna. This phenomenon can be regarded as a result of the relative isolation of the mountains compared with the zonal areas in the context of paleo-enviromental changes since the Pliocene. Their high percentage (26.89) suggests an important process of autogenesis. So the Balkan Peninsula can be considered as a main center of speciation in Europe.
Dippenaar-Schoeman, A. S., Plant Protection Research Institute, Agricultural Research Council, Private Bag X134, Pretoria, South Africa 0001 and Jocque, R., Koninklijk Museum voor Midden-Afrika, B-3080, Tervuren, Belgium
Biodiversity of spiders in Africa: opportunities and challenges.
Africa, especially the subsaharan (Afrotropical) region is characterized by the high diversity of its dominant biomes, ranging from tropical rain forest to desert. By the time Africa had been isolated from the other parts of Gondwanaland, some 100 million YBP, broad leafed forest had come into existence. This vegetation type covered large parts of the continent during several long periods but eventually gave way to an on average much more arid type of vegetation. The present-day spider fauna reflects these drier conditions as 55% of the species are ground dwellers in families that are well adapted to the drier climate, e.g. Gnaphosidae, Lycosidae and Zodariidae. As part of the development of an African Arachnological Database (AAD), a review of and a key to the African spiders have been published. This review indicates that 71 spider families (two-thirds of the world's fauna), 893 genera and about 5450 species are known from the Afrotropical Region. A high percentage of endemism is found, with four families and 56% of the described genera being unique to this Region. Most of the remaining genera have a world wide distribution but 8.6% show elements of a Gondwanian distribution. For most families, information on both the taxonomy and bioecology is lacking or rudimentary. Only 16% of the known genera, belonging to 33 families have been revised. Results of these revisions indicate that on average 41% of the species are new and 24% of the genera are monotypic. We hope this endeavor will create a renewed awareness of African spiders and of the opportunities and challenges it presents.
Dodson, G. N., Biology Dept., Ball State University, Muncie, IN 47306
Crab spider fights: the influences of leg autotomy, body size and experience.
Misumenoides formosipes males locate and guard penultimate females prior to mating. Male-male interactions associated with this guarding can involve grappling and bites, which are potentially lethal. Leg autotomy appears to be a strategy employed to avert the spread of toxin from a bite. Contrary to earlier results, more realistic experiments revealed no disadvantage for males missing a foreleg in contests with fully intact opponents. Body size is a primary predictor of contest outcome. Furthermore, the outcome of an individual's initial contest predicted the result of the next fight between individuals matched for size. In other words, what a male learns from a single experience may determine if he wins or loses subsequent fights.
Draney, M. L., Dept. of Biology, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003, and Crossley, Jr., D. A., School of Ecology, University of Georgia, Athens, GA 30602
Relationship of habitat use to phenology among southeastern ground-dwelling Linyphiidae (Araneae).
Ground-dwelling Linyphiidae from eight South Carolina inner coastal plain habitats were sampled for one year using pitfalls. Habitats formed a gradient of permanence, from a field disturbed yearly and pine stands aged 5, 25, and 40 years, to xeric, mesic and hydric hardwoods (50-75 years) and an old-growth forest of 200. Twenty of the 55 trapped species were represented in sufficient numbers (>10 adults) to examine patterns of phenology and habitat distribution. Half of the species are multivoltine, with adults present throughout the year, continuous reproduction, and overlapping generations; adults peaked during spring through autumn. Other species were univoltine, with adults present briefly, indicating synchronous reproduction and non-overlapping generations; adults always peaked during winter. This article examines relationships between observed voltinism patterns and habitat use (distribution among the habitats) among the 16 most abundant species. There appears to be a relationship between habitat use and phenology: Species from more permanent habitats tend to be univoltine, whereas species inhabiting less permanent habitats were more likely to be multivoltine. Stenochronous winter reproduction (univoltines) probably increases survivorship by limiting individuals' exposure to the harsh conditions of the southeastern summer during vulnerable periods of immaturity and reproduction. This phenological specialization appears optimal in this region except infrequently disturbed habitats, where rapid multivoltine reproduction is most advantageous.
Dunlop, J. A., Institut für Systematische Zoologie, Museum für Naturkunde, D-10115 Berlin, Germany, and Webster, M., Dept. of Earth Sciences, University of California in Riverside, Riverside, CA 92521
Evidence against arachnid monophyly.
A monophyletic Arachnida is currently supported by nine characters in the literature which are here critically reviewed. We argue that reduction of lateral eyes to 5 or less lenses is incorrect, a homologue of slit sensilla may be present in Eurypterida and that both loss of appendages on opisthosomal segment 1 and spermatozoa with coiled axonemes may be synapomorphic for non-scorpion arachnids only. Furthermore, malphigian tubules, a claw depressor originating in the tibia and sperm morphology cannot exclude fossil groups from Arachnida. Extraintestinal digestion, malphigian tubules, loss of a carapace pleural margin and an anteroventrally directed mouth can all be argued as adaptations for, or associations with, life on land. The oldest scorpions were aquatic and scorpions are not ancestral to any other arachnid. This implies that scorpions and non-scorpion arachnids diverged in the water and came onto land independently. These 'synapomorphies' are therefore most likely convergent terrestrial features in arachnids. These arguments do not prove arachnid paraphyly, but we hope to show that the case for monophyly is not as strong as it appears.
Eberhard, W. G., Smithsonian Tropical Research Institute and Escuela de Biologia, Universidad de Costa Rica, Ciudad Universitaria, Costa Rica, and Huber, B. H., Escuela de Biologia, Universidad de Costa Rica
Numb palps: possible links between embryology, lack of innervation and the evolution of male genitalia in spiders.
The male genitalia of spiders apparently lack innervation, probably because they are derived embryologically from structures that secrete the tarsal claw, a structure that lacks nerves. The resultant lack of both sensation and fine muscular control in male genitalia may be responsible for the fact that male genitalia in spiders tend to have more complex internal bracing when in use, and to be less often used to seize or pull open the female, than the genitalia of insects. Apparent difficulties with this proposal are discussed. Previous theories regarding the evolution of spider genitalia are unable to explain several types of data.
Edwards, G. B. Curator, Arachnida & Myriapoda, Florida State Collection of Arthropods, Division of Plant Industry, P.O.Box 147 100, Gainesville, FL 32614-7100 USA
The genus Attidops(Araneae: Salticidae).
The genus Attidops is resurrected from Ballus based, among other characters, on its strongly excavate cymbial tip, different carapace shape, and single retromarginal tooth. The type species, Ballus youngi Peckham & Peckham 1888, is again transferred. Icius cintipes Banks 1900, previously transferred to Ballus,becomes a new combination. Two new species are described.
Edwards, R. L., Res. Assoc. USNM, Box 505, Woods Hole, MA 02543 and Edwards, A. D., MGH, 15 Parkman St., WACC - 333, Boston, MA 02114
Life history notes on Homalometa nigritarsis.
Notes on the life history and webbing of the small metine spider, Homalometa nigritarsis (Simon 1897) from the rainforest of Puerto Rico are provided. This species is typically found on the outer concave surfaces of larger, pendulous leaves of trees in a retreat immediately above which is a closely aligned delicate and virtually invisible orb-web. This spider lays its eggs separately within the retreat in two parallel rows. The rows are produced at intervals; as one row hatches, another is produced shortly thereafter. Evidence of four generations of rows has been observed. The architecture of the orb is similar to that of other small tetragonathoid species with a radius to spiral ratio of less than one. While retaining a traditional orb-web, this small species has adopted a unique habitat and set of life history features.
Erez, Tamar, Mitrani Center for Desert Ecology, Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede-Boqer 84990, Israel
Conflict over mating and female counter-strategies in the spider Stegodyphus lineatus (Eresidae).
Females and males put different amounts of effort into reproduction. Males can mate with many females during their lifetime. A male's fitness usually increases with increasing number of matings. For females, one mating may be enough and further matings might be costly. Immediate costs of mating include loss of energy and time, or exposure to predators. Long-term costs include lower fecundity and fertility of the female. Consequently, female counter-strategies might evolve to reduce the costs of mating. In the spider Stegodyphus lineatus, females suffer immediate costs of mating due to male presence: foraging behavior and food uptake were reduced. A long-term cost of mating existed for females: as the number of male encounters increased the clutch size decreased. In addition females delayed their egg sac production as the number of male encounters increased, which could be either a long-term cost or a female counter-strategy against multiple mating costs. Additionally, loss of body mass due to short-term costs can have a long-term cost of reduced number of young. Females were more aggressive toward second males than toward first males. Female aggressiveness might be an adaptive strategy to reduce mating costs.
Farley, R. D., Dept. of Biology, University of California, Riverside, CA 92521
Ventral mesosomal changes in scorpion embryos.
The SEM was used to examine embryos at a stage when booklungs and spiracles are forming. Earlier studies with scorpion fossils suggest there was ventral mesoso-mal transition from gills or booklungs above flap-like ventral plates to stern-ites, booklungs and spiracles. In Hadrurus arizonensis arizonensis (Iuridae) and Centruroides exilicauda (Buthidae), plates and sternites are demarcated on ventral mesosomal segments before booklung invaginations and spiracles appear. In developmental stages herein examined, em-bryos of the vaejovid, Paruroctonus mesa-ensis, showed no indication of ventral plates or sternites, yet spiracles form in the intersegmental area posterior to body segments XII-XV. Advanced embryos were not available to determine if the early spirac-les are transitory or if they move to a more anterior and lateral position seen in adult mesosomal segments. These results show a vaejovid mesosomal transition different from that hypothesized for Recent scorpions.
Fet, V., Dept. of Biological Sciences, Marshall University, Huntington, WV 25755, USA, andBrownell, P. H., Dept. of Zoology, Oregon State University, Corvallis, OR 97730, USA
Morphological variation in the pectinal sensory organ of scorpions.
Function of the enigmatic abdominal pectinal organ in scorpions (Arachnida, Scorpiones) has been a subject of many speculations. Recently (Foelix, 1984; Gaffin & Brownell, 1992; 1997) it was demonstrated to be an array of cuticular sensillae serving as chemoreceptors, analogous to insect antennae but functional on contact with surface olfactory stimuli. Until now, the detailed microanatomy studies of pectinal organs have been conducted only on a few scorpion species. Our study intended to scan the entire existing evolutionary and taxonomic diversity of the order Scorpiones to reveal existing variation in sensillar microanatomy of pectinal organs. We conducted an exhaustive worldwide SEM survey on the representatives of 50 genera belonging to 12 families (Bothriuridae, Buthidae, Chactidae, Chaerilidae, Diplocentridae, Euscorpiidae, Ischnuridae, Iuridae, Scorpionidae, Scorpiopsidae, Superstitionidae and Vaejovidae. SEM images demonstrate a variety of sensillar sizes, shapes, and densities. Size varies from 3 micrometers (most desert Buthidae) to almost 30 micrometers (Euscorpius germanus), with average 6-7 micrometers length. The most commonly found shapes are cylindrical or triangular (a "spade"). Density of sensilla on the ventral surface of each pectine varied between 10-20 per 1000 sq. micrometers; Buthidae, as a rule, have higher density (20+). Detected extreme densities (per 1000 sq. micrometers) ranged from 3 (Scorpiops, Heterometrus) to 29 (Centruroides). Distribution of sensillar types and its bearing on the evolutionary relationships and function within the order are discussed.
Fet, V., Dept. of Biological Sciences, Marshall University, Huntington, WV 25755, USA, Sissom, W. D., Dept. of Life, Earth, & Environmental Sciences, West Texas A & M University, Canyon, TX 79016, USA, Lowe, G., Monell Chemical Senses Center, Philadelphia, PA 19104, USA and Braunwalder, M. E., Arachnodata, Zurich, CH-8045, Switzerland
Catalogue of the scorpions of the world (1758-1997).
Scorpions (Chelicerata: Scorpiones) are a unique, well-defined, well-known order of terrestrial arthropods which have received attention from many a taxonomist, including Linnaeus (1758, 1767) himself. The only complete survey of the world fauna, with keys to all taxa, was published approximately 100 years ago by Kraepelin (1899). At that time, approximately 400 species and subspecies of scorpions were recognized. Today, as a result of numerous taxonomic revisions, regional studies, etc. this number has almost quadrupled. Further, the higher classification is now quite different from that used by Kraepelin, and it continues to change as phylogenetic relationships become better understood. All this precipitated our decision to assemble the existing data on scorpion taxonomy and nomenclature into a catalog of all known scorpions (extant as well as fossil), which is intended to be a comprehensive, indexed reference text that assesses the current state of scorpion taxonomy. This project is now complete as a result of more than six years of collaborative work. Our Catalog includes the following currently valid extant scorpion taxa: 13 families, 16 subfamilies, 143 genera, 30 subgenera (including ten nominotypical), 1189 species, and 371 subspecies (including 115 nominotypical). Extinct scorpions are represented by 42 families, 71 genera, 92 species, and one subspecies. We list data on synonymy, type specimens, all major references, and geographical distributions for all taxa. Existing problems in scorpion taxonomy and nomenclature are discussed.
Gaffin, D. D., Dept. of Zoology, University of Oklahoma. Norman, OK 73019, and Turner, T. A., Dept. of Zoology, University of Oklahoma. Norman, OK 73019
Electrophysiological properties of peg sensilla on the pectines of a buthid scorpion (Centruroides vittatus).
The pectines of scorpions are unique, ground-directed appendages that extend from the second mesosomal segment of all scorpions. The teeth of these comb-shaped organs contain thousands of minute peg-shaped sensilla that make apparent contact with the substrate as the animal brushes its pectines over the ground. Electrophysiological recordings made from the bases of individual peg sensilla of Centruruoides vittatus typically contain three to four spontaneously active cells. Two of these cells show baseline spiking activity at frequencies of 1-10 Hz, have distinctive double-peaked waveforms, and have spike durations of approx. 4 ms. A third spike class has a smooth, biphasic waveform, is shorter in duration (2.5 ms), and frequently fires in phasic bursts of 15-20 Hz for approx. 10 seconds. In high quality recordings, a fourth spike class, biphasic in waveform, is sometimes detectable above noise. Additionally, some recordings contain a fifth class with a distinctive, large amplitude, biphasic waveform that is induced by gentle tapping on the electrode holder. This putative mechanoreceptor fires phasically with spiking frequencies exceeding 200 Hz, has an initial negatively-going waveform (reversed that of other cells in the peg), and a spike amplitude often twice that of the spontaneously active cells. Cross-correlation analysis of identified units detected both excitatory and inhibitory interactions between specific spike classes within individual peg sensilla. Taken together with previous morphological, physiological, and behavioral studies of scorpion pectines, it appears that information transduced in peg sensilla of C. vittatus is processed in the periphery prior to its relay to the CNS.
Gajdos, P., Institute of Landscape Ecology, Bratislava, Branch Nitra, Slovak Academy of Sciences, Akademicka, POB - 23B, 949 01 Nitra, Slovak Republic, and Toft, S.,Dept. of Zoology, Institute of Biological Sciences, University of Aarhus, Building 135, DK- 8000 Aarhus, Denmark.
A 20 year's comparison of epigeic spider communities (Araneae) of Danish coastal heath habitats.
The epigeic spider communities of NW Jutland (Denmark, region Thy) coastal heath habitats, initially examined by pitfall traps in 1977-1979, were examined 20 years later (1997-1998) on the same plots. Between the investigations the heath plots, which represent open sandy area growing into Calluna heath, and more stable Erica,Calluna/Empetrum, Molinia vegetation types, have changed only a little due to natural succession. The spider communities of all areas showed larger differences between the two periods than between the different habitats, in spite of large differences in soil humidity and the structure of their vegetation .
Garb, J. E., Zoology Dept., University of Hawaii at Manoa, Honolulu, Hawaii 96822
Molecular insights into a radiation of Hawaiian Thomisidae.
The family Thomisidae, commonly known as crab spiders, is one of the few spider families containing genera that are known to be exceptionally diverse in the Hawaiian archipelago. This diversity led early systematists to place the twenty-one described Hawaiian species in several unrelated genera. However, recently it has been suggested that these species constitute a large radiation descended from a single colonization event. My research focuses on understanding whether the tremendously diverse and confusing morphology found across these Hawaiian species is the result of a single colonization event followed by extremely rapid speciation. I have examined the origin of the Hawaiian thomisids using molecular phylogenetic techniques. A 505 bp region of the mitochondrial gene cytochrome oxidase I was amplified and sequenced from 14 Hawaiian thomisid species as well as eight outgroup species. Analysis of these sequences using maximum likelihood methods suggests that the Hawaiian thomisids have descended from at least two separate colonization events. However, the 14 Hawaiian species sampled are not closely related to the genera to which they were originally assigned. Sequence divergence across the Hawaiian species is low, indicating that extensive adaptive speciation within the Hawaiian islands may account for much of the diversity of its crab spider fauna.
Gillespie, R. G., Center for Conservation Research & Training, University of Hawaii, 3050 Maile Way, Gilmore 409, Honolulu, HI 96822
Community evolution in a lineage of Hawaiian spiders.
Phylogenetic analysis is used to examine convergence of ecological equivalents among a radiation of spiders (genus Tetragnatha) in Hawaii. Because the islands are arranged in chronological series, communities of different stages of evolutionary development can be compared. The results indicate that similar sets of ecomorphs have evolved independently on each island. The youngest island contains few endemic species - most taxa are shared with East Maui, the next youngest island in the chain. East Maui, however, has more than 2 times as many endemic species than any other volcano. All the older mountains have a single representative of each ecomorph. Together, the results suggest, first, that local processes play a major role in dictating community organization. Second, competition appears to play a role only later in community development: Initially, ecomorphs arrive at a site, either by dispersal or evolution in situ, under condition of reduced competition. Accordingly, in contrast to previous studies in which competition has been implicated as the mechanism driving adaptive radiation, the results here suggest that adaptive radiation may be initiated under conditions of very low competition.
SAGreenstone, M. H., U.S.D.A. - Agricultural Research Service, Stillwater, OK 74075
Spider predation: how and why we study it.
Predation is of great theoretical ecological, evolutionary and behavioral interest, but for our present purposes the primary reason for studying it is to determine the role of spiders in suppressing pest populations. Research approaches have included laboratory studies of preference, feeding rate, and fitness; direct observation of predation events or accumulations of prey carcasses; gut analysis; and field experiments. Laboratory feeding studies provide some uniquely useful kinds of information but cannot give reliable indications of the "biological control potential" of spiders against a given pest. Direct observation can be powerful; it has provided the best data on dietary range and predation rates in the field. Gut analytical methods include the use of radionuclides, electrophoresis, chromatography and serology. Serological techniques are the methods of choice: they are sensitive and can be made specific down to the level of prey stage or instar, and assays are simple and reliable. They can determine the relative importance of different predator species, and may be the most efficient methods to document predation on eggs. Problems in quantitation remain to be solved. Experimental field methods have demonstrated unequivocally that spiders can be effective in reducing pest populations and the crop damage they cause. Curiously, although published spider functional responses are non-density-dependent, single spider species have sometimes reduced pest populations in field experiments.
HPGriswold, Charles E., Dept. of Entomology, California Academy of Sciences, Golden Gate Park, San Francisco, CA 94118, USA, Coddington, Jonathan A., Dept. of Entomology, National Museum of Natural History, NHB-105, Smithsonian Institution, Washington, D.C. 20560, USA, Platnick, Norman I., Dept. of Entomology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA, and Forster, Raymond R., McMasters Road, R. D. 1, Saddle Hill, Dunedin, New Zealand.
An outline of the phylogeny of entelegyne spiders (Araneae, Araneomorphae).
A data matrix comprising 137 characters scored for 43 exemplar taxa representing every araneomorph group retaining the cribellum was subject to phylogenetic analysis using parsimony. The resulting cladogram suggests that the Neocribellatae, Araneoclada, Entelegynae, and Orbiculariae are monophyletic, Lycosoidea (sensu Homann 1971, Griswold 1993) are paraphyletic, and the Amaurobiidae (sensu Lentinen 1967) and Dictynoidea and Amaurobioidea (sensu Forster and Wilton 1973) are polyphyletic. The positions of Phyxelididae Griswold and Udubidae Griswold are clarified.
PLHarvey, M. S., Dept. of Terrestrial Invertebrates, Western Australian Museum, Francis Street, Perth, W.A. 6000, Australia
The neglected cousins: what do we know about the 'minor' arachnid orders?
While our knowledge of the relationships and phylogeny of the two largest arachnid orders, Araneae and Acari (the latter is often divided into three or more orders), has been increasing progressively over recent years, the same cannot be said for all of the smaller orders. This talk attempts to provide a summary of our basic taxonomic and systematic knowledge of seven of these orders (Amblypygi, Uropygi, Schizomida, Palpigradi, Ricinulei, Solifugae and Pseudoscorpiones), and to highlight gaps in our knowledge base. Recent advances include the publication of cladistically derived phylogenies for the genera of Amblypygi (Weygoldt, 1996) and the families of Pseudoscorpiones (Harvey, 1992), each of which proposed novel classificatory systems. The fossil species of Ricinulei were treated by Selden (1992), who placed the fossil and Recent species in separate suborders. The remaining four arachnid orders suffer from the lack of detailed phylogenetic work, which has resulted in many paraphyletic clades. Some examples of how members of the 'minor' orders have helped elucidate biogeographic patterns are also included. While the numbers of undescribed species of the smaller orders does not even begin to approach that of spiders or mites, it is clear that much systematic work is needed before we will have a sufficient grasp of the true diversity of many of these groups. The ageing workforce of specialists available to describe the fauna of some regions is also highlighted.
Haughton, A. J., Crop & Environmental Research Centre, Harper Adams College, Newport, Salop TF10 8NB UK, Bell, J. R., Dept. of Environmental & Geographical Sciences, Manchester Metropolitan University, Manchester, M1 5GD UK, Boatman, N. D., Allerton Educational & Research Trust, Loddington House, Leicestershire, LE7 9XE UK, and Wilcox, A., Crop & Environmental Research Centre, Harper Adams College, Newport, Salop, TF10 8NB UK
The effects of different rates of the herbicide glyphosate on spiders in arable field margins.
Field margins are susceptible to agro-chemical spray drift and the effects of herbicide on spiders in semi-natural habitats have been little studied. In this experiment, an arable field margin was sprayed with 3 rates of glyphosate (90g a.i./ha, 180g a.i./ha & 360g a.i./ha) and control plots left unsprayed. Spiders were sampled monthly (June-October) using a converted garden-vac and adult spiders were identified to species. A total of 23,393 spiders were sampled with the web-spinners representing more than 90% of the individuals. The effects of glyphosate application on the abundance of wandering and web-spinning prey-capture guilds, Gonatium rubens (Blackwall 1833) and Lepthyphantes tenuis (Blackwall 1852) were analyzed using ANOVA F tests. The highest rate of glyphosate was consistently shown to significantly reduce the total number of spiders, and the numbers of web-spinners, G. rubens and L. tenuis, but not numbers of wandering spiders. Changes in vegetation structure and microclimate caused by the glyphosate are implicated in the reduction of numbers of spiders in plots receiving the highest rate of glyphosate. We conclude that glyphosate drift at rates of more than 360g a.i./ha into arable field margins could result in significant losses of important arthropod predators in farmland and a reduction in spider biodiversity in agroecosystems.
Hebets, E. A., Dept. of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721
Life underwater: a novel mode of respiration in the amblypygid Phrynus marginemaculata(Arachnida, Amblypygi).
Although arachnids originated from aquatic ancestors, all eleven extant orders (with the exception of some mites) are believed to be purely terrestrial. These orders encompass a tremendous diversity of respiratory systems, including amblypygids with 2 pairs of book lungs, that function in terrestrial respiration. This study describes an evolutionary innovation within the order Amblypygi that allows for underwater respiration. Specimens of Phrynus marginemaculata (Phrynidae; Amblypygi) were shown to voluntarily proceed underwater and remain there for up to 8 hours. Three hypotheses that attempt to explain the mechanism(s) allowing for this behavior will be examined: (1) bubble respiration; (2) reduced metabolic rates; and (3) plastron respiration. Behavioral data as well as data obtained from scanning electron microscopy and paraplast sectioning support the hypothesis that P. marginemaculata is able to breath underwater by means of a cuticular plastron. This study represents the first discovery of plastron respiration within the order Amblypygi along with the first discovery of a plastron in an organism with book lung respiration. The implications of this evolutionary innovation will be discussed, including the distribution of plastron respiration throughout the order Amblypygi and speculations as to the selection pressures thought to be important in the origin of plastron respiration.
Hedin, M. C., Dept. of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721 and Maddison, W. P., Dept. of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721
Phylogenetic analyses of courtship-related character evolution in the salticid genus Habronattus.
Male spiders of the salticid genus Habronattus exhibit an extraordinary diversity of behavior and morphological ornamentation related specifically to courtship display. As first pointed out by G. and E. Peckham, these phenotypes typically comprise a tightly co-evolved functional complex (e.g., one can predict the basic form of display behavior based on morphological characteristics, and vice versa). The work presented here focuses on instances of an apparent lack of such coevolution. Using a molecular phylogenetic framework, we will show that (1) many Habronattusspecies lacking specific morphological ornaments belong in clades dominated by ornamented members, (2) the lack of such ornamentation is secondary (i.e., ornaments have been lost), (3) in several cases, behavioral elements associated with a morphological ornament are retained (i.e., the spiders behave as if an ornament still exists). Discussion of these data will focus on the potential causes and subsequent consequences of ornament loss, with particular emphasis on ornament "turnover" and multiple ornament theory.
Hedin, M. C., Dept. of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721 and Maddison, W. P., Dept. of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721
Salticid phylogeny from molecular data.
Sequence data for three mitochondrial (16S, NADH-1, CO1) and two nuclear (28S, EF1-alpha) genes were gathered for various salticid and outgroup genera (for 83, 81, 81, 69 and 17 genera respectively). Phylogenetic analyses support the monophyly of some previously recognized groups: dendryphantines, marpissines, pellenines (Habronattus, Pellenes, Hawaiian "Sandalodes"), plexippines, and euophryines. Dendryphantines are placed as sister to marpissines, and pellenines to plexippines. The evolution of an articulated embolus in dendryphantines and euophryines appears independent. Best resolved trees come from 28S and EF1-alpha. For the most part, the taxa expected to come out near the base of the tree (Lyssomanes, spartaeines) do, but these deeper relationships are poorly resolved.
Herberstein, M. E., Dept. of Zoology, University of Melbourne, Parkville Victoria, 3052 Australia
The effect of light level and background color on web construction in Argiope keyserlingi(Araneae: Araneidae).
The amount of light reflected from the silk of spider webs may influence the prey capture success of spiders in several ways. While the reflection of UV-light may attract prey to the web site, the reflection of visible light may increase web visibility and result in insect prey detecting and avoiding the web. Similarly, the background against which the web is placed may also influence web visibility. Consequently, spiders are expected to adjust their web building behavior under different light conditions and in front of various backgrounds. In two separate experiments Argiope keyserlingi Karsch spiders were exposed to two different light levels (approx. 700 and 90 Lux) and two different backgrounds (black and white) in a paired design. The webs constructed in three dimensional frames under the different light and background treatments were compared. Spiders under dim light conditions constructed larger webs investing a longer capture thread and placed significantly more web decorations (or stabilimenta) in the web compared to brighter conditions. Varying the background however did not result in significant differences. Reducing the amount of silk under bright conditions may also reduce web visibility, while placing more decorative bands in the webs under dim conditions may increase the amount of UV-light reflected from these structures. Alternatively, spiders may be less exposed to visually hunting predators under dim light conditions and consequently invest more time and silk into the web.
SAHodge, Margaret A., Dept. of Biology, The College of Wooster, Wooster OH 44491
The implications of intraguild predation for the role of spiders in biological control.
Evidence is growing that spiders can be effective biological control agents. Other evidence finds that spiders prey on each other and other generalist predators, and as such are of limited value in biological control. Such predatory interactions between species which use similar resources have been dubbed intraguild predation due to their potential to modify competition, as well as cause direct mortality. Such interactions can have unexpected effects at other trophic levels, and sometimes result in enhancement of a pest population. In this paper I review the evidence for intraguild predation interactions involving spiders in natural systems, and other generalist predators in agroecosystems. To date not much research has examined whether such interactions influence spider biological control potential. Some suggestions as to how we might begin to address these issues are presented.
HPHormiga, Gustavo, Dept. of Biological Sciences, George Washington University, Washington, D.C. 20052, USA
Higher level phylogenetics of erigonine spiders (Araneae, Linyphiidae, Erigoninae).
This paper provides the first quantitative cladistic analysis of erigonine phylogenetic relationships based on a sample of taxa. A total of 73 characters, most of them morphological, have been scored for 31 erigonine genera plus 12 outgroup taxa. The parsimony analysis of these data supports the monophyly of Erigoninae based on two synapomorphies: the male pedipalpal tibial apophysis(es) and the loss of the female pedipalpal claw. The monophyly of Linyphiidae and of Linyphiidae plus Pimoidae is also supported. One of the largest clades within the erigonines is the "distal erigonines," whose monophyly is supported by the loss of the taenidia in the tracheoles and the loss of the distal dorsal spine of tibia IV. The clade composed of Stemonyphantinae plus Mynogleninae is the sister group of Erigoninae. A number of relatively "basal" erigonine lineages which have been classically regarded as "taxonomically problematic" or "transitional" retain some plesiomorphic characters typical of other subfamilies, like the haplotracheate system or taenidia in the tracheoles. The available data suggest that the cephalothoracic sulci and glands found in mynoglenines and erigonines are not homologous.
Huber, B. A., Dept. of Entomology, American Museum of Natural History, Central Park West at 79th Street, New York, N.Y. 10024, USA
Sexual selection in pholcid spiders: artful chelicerae and forceful genitalia.
Two aspects of pholcid reproductive biology are reviewed and appear best explained by sexual selection by female choice: the rapid and divergent evolution of male chelicerae (and clypei in some groups) which contact the female epigynum during copulation and probably act as copulatory courtship devices; and the often exceptionally strong pedipalps in males, which possibly function in correlation with the 'valve' in the internal female genitalia.
Jäger, P., Institute for Zoology, Johannes Gutenberg-University of Mainz, 55099 Mainz, Germany
A new heteropodine genus from SE-Asia (Araneae: Sparassidae).
A new heteropodine genus (Araneae: Sparassidae: Heteropodinae) is described from SE-Asia. It is related to Heteropoda Latreille 1804 and other undescribed genera. It can only be recognized by genital characters as in Yiinthi Davies 1994. Male palps have a bifurcate embolus. The conductor is developed membraneously and it arises always on the distal part of the tegulum. In Heteropoda the conductor is longer, sheath-like and arises on a prolateral or basal position of tegulum. The tibial apophysis of the new genus has a characteristic bifurcate shape with a longer dorsal branch. The female's uncoiled insemination ducts run from anterior genital openings to posterior spermathecae. Mostly they are fused at the median line. Head of spermathecae can run into the anterior part of insemination ducts. In Heteropoda insemination ducts are coiled and touch each other at most in the beginning part. Eye position, shape of carapace in lateral view, spination etc. varies within this group and do not allow distinguishing the new genus from Heteropoda or other related genera. At present the new genus comprises 24 species: Heteropoda campanaceaWang 1990, H. forcipata Karsch 1881, H. hamata Fox 1937, H. koreana Paik 1968, H. licenti Schenkel 1953, H. marsupia Wang 1991(?), H. minschana Schenkel 1936, H. serrata Wang 1990, H. shennonga Peng, Yin & Kim 1996, H. stellata Schenkel 1963, Panaretidius microphthalmus Fage 1929 and 13 undescribed species. The new genus is distributed from Japan to Korea, China, Thailand and Borneo.
Jakob, E. M., Dept. of Entomology, University of Massachusetts, Amherst, MA 01003, and Pollack, Jeannine, Dept. of Biology, Bowling Green State University, Bowling Green, OH 43522
Rearing environment affects salticid behavior.
We present here new analyses of an experiment testing the effect of rearing conditions on the behavior of jumping spiders (Phidippus audax). Spiders were randomly assigned to either small or large cages that either were empty or environmentally "enriched" with a painted dowel. Lab-reared spiders were raised from second instar to adult in these environments. Field-caught adults were also randomly assigned to these containers and were held for four months prior to testing. Spiders were then presented with three behavioral tests. Data were analyzed with ANOVA and multiple logistic regression, enabling us to test simultaneously the effects of cage size, enrichment, and source (lab vs. field). Field-caught spiders were more active, and spent more time in the center of an open field, than did lab-reared spiders. Spiders from the enriched environment were also more active. Field-caught spiders were more likely to orient to and approach videotapes of prey, as were spiders from enriched environments. Spiders from large cages approached the videotape from a further distance than from small cages. Finally, we found significant effects of origin and cage size on the ability of spiders to complete a detour test. Our results suggest that the rearing conditions we tested, which are commonly used by behavioral researchers, may profoundly influence the behavior of adult spiders.
SAJepson, P. C., Depts. of Entomology, and, Environmental and Molecular Toxicology, Oregon State University, Cordley Hall, Corvallis, OR 97331
Spiders and community and agroecosystem processes: pesticidal effects.
Modern ecotoxicological research acknowledges that there are ecological, toxicological and chemical dimensions to the analysis of pesticide side effects. Although we are aware that spiders are sensitive to a large number of pesticides, our knowledge of the physiological tolerances of spiders, levels and routes of exposure to pesticides, uptake and elimination rates, and population consequences of lethal and sub-lethal effects is extremely limited. We cannot therefore predict when and where hazards will arise, or determine the consequences that a particular pattern of use of a pesticide will have for spiders or the equilibrium population densities of the pests that they consume. The quality of the research studies that have been undertaken is high, despite their low number, and spiders have been model organisms for the development of terrestrial invertebrate ecotoxicology. This paper will outline where our current knowledge lies, explore some of the classical studies that have been undertaken throughout the world, and examine the questions that need to be asked and the research approaches that could be used to answer them.
Jocqué, R., Royal Africa Museum, B-3080 Tervuren, Belgium
Female choice, a secondary effect of "mate check"? A hypothesis applied to arachnids.
A new hypothesis is formulated to explain the diversity and the range of complexity of secondary sexual characters (SSC). It is based on the statement that in many spider groups, an important somatic radiation (genera or higher level taxa in Lycosoidea, Zodariidae, Liocranidae) took place whereas palpal conformation remained fairly uniform and palpal complexity low. For some well-studied genera it is shown that, apparently in a later stage, palpal complexity increased dramatically while somatic morphology remained stable. SSC are therefore supposed to be linked to hidden (behavioral), but crucial traits that have been acquired in the last steps of the taxon's evolution. The mating process is supposed to be construed thus that it guarantees the presence of these characters. During this process the "mate is checked". The reason for this mechanism is to avoid the loss of crucial behavioral adaptations by deleterious mutations. The hypothesis might explain why taxa with a flexible checking system (e.g. stridulation, nuptial dance) are more speciose than those which use only morphological clues, since the complexity and variation limits are then reached earlier. Systems that allow larger variation (e.g. entelegyne versus haplogyne) without compromising the survival of the adult male, will allow a wider radiation. As complexity of SSC is supposed to be correlated with specialization, families with smaller species can be expected to have more complex SSC (e.g. Linyphiidae, Mysmenidae). Female choice is supposed to be a secondary effect of the "mate check" mechanism. The former only plays in optimal habitats where a wide range of the male's signal strength is to be expected. In marginal habitats it is likely to disappear because both female coyness and range of male signal strength are assumed to drop. In contrast to female choice, mate check is supposed to be a stabilizing mechanism.
Kiss, B. and Samu, F., Plant Protection Institute of the Hungarian Academy of Sciences, P.O. Box 102 Budapest, H-1525 Hungary
Evaluation of population densities of Pardosa agrestis Westring (Araneae: Lycosidae) in Hungarian alfalfa fields using mark-recapture.
In Hungarian arable land Pardosa agrestis is the most dominant epigeic spider. We aimed to quantify its absolute population density in two alfalfa fields by multiple mark-recapture method. Two experiments were conducted in August 1995 and 1996. Grids of 11x11 live-catching pitfall traps, with 2m (1995) and 3m (1996) trap distances were established. Traps were emptied daily. Newly caught adults received an individual painted dot code. The animals were set free near the trap where they were caught. 5356 spiders were marked in the two experiments. The number of spiders caught varied greatly between days. The recapture rate was 18.7% in the first experiment and 5.4% in the second. The marked animals left the trapping area in a few days. We found a strong correlation between days until recapture and distance covered. Population sizes were estimated in 3 day long sliding windows, using the Mt model of "CAPTURE" program. Spider densities were calculated from weighted means of the estimated abundance and the capture area which consisted of the grid area plus a boundary strip calculated from the estimated movement ranges of spiders. The resulted densities were 1.85 males and 0.82 females per m2 in 1995, 4.5 males and 4.5 females per m2 in 1996.
Kissane, Kelly C., Dept. of Entomology, University of Maryland, College Park, MD 20742
The effects of lab rearing on the courtship behavior of Dolomedes triton.
The behavior of vertebrate animals has long been known to be affected by laboratory conditions, but few studies have been conducted on invertebrates, whose behavior is believed to be "hard-wired". A study was conducted to compare the courtship behaviors, female receptivity and mating success of males that were reared throughout their life cycle in a laboratory with males that were wild-caught. A sequential analysis of courtship behavior revealed no significant differences in the behavioral characteristics between lab-reared and wild males. No significant differences were found in female receptivity between lab-reared and wild males. Analysis of mating success, however, showed a highly significant difference. All lab-reared males, despite strong similarity in courtship behavior and female receptivity to their courtship, failed to complete copulation.
Kreiter, N. A., Dept. of Biology, College of Notre Dame of Maryland, Baltimore, MD 21210, and Wise, D. H., Dept. of Entomology, University of Kentucky, Lexington, KY 40546-0091
Prey availability limits reproduction and influences foraging effort in Dolomedes triton: evidence from a field experiment.
It has been argued from indirect evidence that reproduction in fishing spiders of the genus Dolomedes(Araneae: Pisauridae) is not food-limited. However, our previous report of increased movement by female Dolomedes triton following maturation suggests that females of this Dolomedesspecies are food limited in nature. We conducted a food-supplementation field experiment to directly test two hypotheses: (1) reproduction in natural populations of female D. tritonis limited by prey availability during the adult stage; and (2) the increased activity of adult female D. triton is an adaptive behavioral response to increased energy demands of reproductive activity. Marked adult females were assigned to a food-supplemented group (n = 158) that received crickets added to their diet or to a control group (n = 173) that received no additional prey. Juvenile female spiders (n = 283) were also marked and followed for comparison with adult females, but were not offered additional food. Supplemented females gained weight at a faster rate and hatched more than twice as many spiderlings as the control females. Supplemented females also moved shorter distances per day than control females; the movement pattern of the former did not differ from that of juveniles. Female spiders in the control group moved significantly greater distances per day than juveniles. These results support our hypotheses that reproduction in adult female fishing spiders are resource-limited in the field. Increased movement by females at maturity may represent a foraging switch resulting from the increased demand for energy during reproduction.
Kroeger, D. E., Dept. of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, 45221-0006
Sexual selection in the colonial spider Metepeira incrassata (Araneae, Araneidae)
The colonial spider Metepeira incrassata lives in groups that can number thousands of individuals. Tradeoffs with spatial position in large colonies force a size biased dominance hierachy among reproductive females. Females compete for central locations in the colony that confer fitness advantages. The mating system is dominated by male aggression over females, especially penultimate females within days of their ultimate molt. Males guard penultimate females in silken retreats and face tradeoffs when competing against multiple intruders for periods that may span several days. Data collected from field studies in Fortin de las Flores, Veracruz, Mexico, used marked individuals to quantitatively describe the mating system of large colonies. Males spent approximately twenty percent of their time in foraging activities and up to forty percent in reproductive activities (guarding, interacting over, and courting females). Larger spiders performed better than smaller ones in both single encounters and in repeated combat events over time. They were better able to gain and to maintain residency of females. Larger males were more likely to mate and seemed to invest in higher quality females which may have increased their fecundity. Finally, evidence that males were able to assess differences in female value associated with female size, location, and time remaining before their ultimate molt are shown in patterns of male behavior. The data suggest a complex mating system where males must balance time and energy to maximize their reproductive effort by assessing the potential value of females available and choosing one that can be economically defended until the ultimate molt.
Kropf, C., Natural History Museum Berne, Dept. of Invertebrates, Bernastrasse 15, CH-3005 Berne, Switzerland
Morphological population differentiation of Acantholycosa norvegica (Thorell, 1872) in Central Europe (Araneae: Lycosidae).
The wolf spider Acantholycosa norvegica shows an arcto-alpine distribution. The Central European populations are regarded as a separate subspecies at present, A. norvegica sudetica (L. Koch, 1875). This subspecies is characterized by a median rib on the anterior part of the epigyne. Comparative morphological investigations of specimens from different Central European locations reveal unexpected high geographic variation of epigynal characters: Specimens from the Swiss Jura Mountains have a uniform anterior part of the epigyne without a rib whereas specimens from the Rhön Mountains (Germany) and the Eastern Alps (Austria) show two parallel vertical ?lips there. It is concluded that only specimens from the Sudetic Mountains and adjacent regions should be assigned to A. norvegica sudetica.
PLKury, A. B., Museu Nacional, Quinta da Boa Vista, São Cristóvão, 20.940-040, Rio de Janeiro - RJ - Brazil
Laniatores -- 100 years of study of spiny harvestmen: overview of their research in the world in the XX century.
The research activity on Laniatores in the XX century is divided in four periods. The Old Age (1911-1949) is dominated by C.F. Roewer with strong participation of C.F. Mello-Leitão and the Goodnights. In this period occurred the recognition of the traditional families and subfamilies, and extensive descriptions of new genera and species. The drawbacks include a multiplication of monotypic genera and subfamilies and disdain about relationships and accurate rendering of localities. The Middle Ages (1950-1965) showed a drop of output (featuring Lawrence, Ringuelet), bringing, however, important basal reformulation on the higher systematics of the Laniatores, with proposals of suprafamilial taxa (Kratochvil, Šilhavý). The Early Renaissance (1966-1985) is marked by uniformity in the output of most authors, routine descriptions of male genitalia and the first attempts to do phylogenetic systematics (Martens). Communication among authors and joint authorship were relatively rare. As in the past periods, the reviewers rarely cared about collections in other countries - the most common subject is "Study of material collected by someone somewhere". The New Wave (1985-1998) is marked by a great exchange of information among authors, cladistics, catalogues, taxonomic reviews including material from museums in diverse continents, including the old types and the presence of authors who started a career on other arachnids, such as Maury, Schwendinger, Cokendolpher and González-Sponga.
Ledford, J. M., Dept. of Entomology, Bohart Museum of Entomology, University of California in Davis. Davis, CA 95616, and Griswold, C. E. Dept. of Entomology, California Academy of Sciences, Golden Gate Park. San Francisco, CA 94118
A phylogenetic analysis of the trap-door spider family Migidae (Araneae: Mygalomorphae).
A phylogeny of the trap-door spider family Migidae is presented and the interrelationships among genera are discussed. All currently described migid genera were included in the analysis along with 7 undescribed taxa from Madagascar. The trap-door spider families Idiopidae, Ctenizidae, and Actinopodidae were selected as outgroups in order to test the monophyly of the Migoidea sensu Raven (1985) and Goloboff (1993). Forty one characters generated a tree of 92 steps with a consistency index of 0.587. The Miginae and Migidae retain their monophyletic status. The subfamily Miginae is judged to be monophyletic, however the subfamilies Calathotarsinae and Paramiginae are paraphyletic and need to be reevaluated.
HPLehtinen, P. T., University of Turku, 20014 Turku, Finland
Main lines of evolution in the spider family Thomisidae.
Suprageneric taxa of Thomisidae are revised, based on unpublished generic revisions. Most taxa were studied also with SEM and phylogenetic analyses with HENNIG86. The cladogram is for named and new groups only. The subfamilial key-characters (e.g., cheliceral teeth and tarsal claw tufts) are either plesiomorphies or parallel adaptations. The hair pattern of the posterior cheliceral face is the most convincing synapomorphy. Papulous leg skin, abdominal modifications, tutacular structures, disc-shaped tegulum, tripartite tibial apophysis and short IV leg are widespread, but not familial synapo- morphies. Male genitals and leg ultrastructure afford most synapomorphies for suprageneric taxa. The Thomisidae are related to unrevised "Corinnoidea". The placement of several genera is discussed. Many poorly collected genera could not be placed.
Leighton, E. L. and Miller G. L., Dept. of Biology, University of Mississippi, Oxford, MS 38677
Reproduction and the risk of predation on the web-invading spider Argyrodes trigonum.
We investigated if the two preferred hosts of A. trigonum presented a significant risk of predation to reproducing males as they preformed courtship displays in the presence of the host. We predicted that courting males would be under a greater risk of predation on the smaller webs of Neriene radiata then on the larger webs of Latrodectus variolus. Furthermore, we predicted that if males were attacked by the host they would utilize an alternative courtship strategy to avoid further aggression by the host. To test these predictions we used a replicated 2x2 factorial design in which males were exposed to different treatment combinations of the presence and absence of the host and female. We found that there was no difference in the courtship behavior of males exposed to the presence or absence of N. radiata. However, on two occasions N. radiataresponded to the male's courtship behavior by violently tugging on the web and approaching the male. In both situations the male made no attempt to avoid the aggression by the host and continued to court the female until copulation. Although males exposed to the webs of L. variolus were never attacked by the host, they were less likely to perform courtship on the widow's web. In every sample in which the male preformed courtship in the presence of the female he achieved copulation.
Lise, A. A., Curso de Pós-Graduação em Biociências, Pontificia Universidade Católica do Rio Grande do Sul, Av. Ipiranga, 6681 Prédio 12C, Sala 244, Porto Alegre, RS, Brasil
Systematic revision of the species of Acentroscelus Simon, 1886 of the Neotropical Region (Araneae, Thomisidae, Thomisinae).
The name Acentrosceluswas first used by Simon in 1886 as a new name for Achantonotus, a pre-occupied name used by Taczanowski in 1873. On the same occasion, Simon transferred Achantonotus guyanensis Taczanowski 1873 and Achantonotus peruvianus Keyserling, 1880 to Acentroscelus. Mello-Leitão, in 1929, described Acentroscelus granulosus, Acentroscelus nigrianus andAcentroscelus secundus. Soares, in 1942, described Acentroscelus versicolor. In 1943, Mello-Leitão added two new species to the genus, Acentroscelus gallinii and Acentroscelus ramboi and in 1947 another one, Acentroscelus muricatus. In 1984, Rinaldi transferred Wittickius singularis Mello-Leitão, 1940 to Acentroscelus. In the present revision, Acentroscelus peruvianus Keyserling,1880 and Acentroscelus secundus are considered incertae sedis because they are not congeneric with Acentroscelus. Acentroscelus nigrianus Mello-Leitão, 1929 and Acentroscelus gallinii Mello-Leitão, 1943 are considered species inquirendae because the descriptions were made upon juvenile specimens. The male of Acentroscelus versicolor Soares, 1942 and the one of Acentroscelus ramboi, Mello-Leitão, 1943 are described as new. As new are also described the following species: Acentroscelus sp.n. 1 from Maracá Island, Acentroscelussp.n. 2, from Gurupi, Pará, Acentroscelus sp.n. 3 from Rio Grande do Sul and Paraná, Acentroscelus sp.n. 4, from Brasil and Curaçao (?), Acentroscelussp.n. 5, from Manaus, Acentroscelus sp.n. 6, from Caixuanã, Pará andAcentroscelus sp.n. 7, from Rio Samiria, Peru.
Locht, A., Yañez, A. and Vazquez, I. M., Laboratorio de Acarologia "Anita Hoffmann" Facultad de Ciencias, UNAM. 04510 D.F. Mexico
Brachypelmides, a synonym of Brachypelma?
In 1994, Schmidt & Krause, wrote an article that described a new genus named Brachypelmides, showing as type species B. klaasi sp. nov. It was collected in the West Coast of Mexico, in Tepic, Nayarit state. They established that this species should be put in this new genus, although they agreed that B. klaasi is very similar to the species of Brachypelma. After several field trips and the study of different tarantula collections, we have found that the genus Brachypelmahas a distribution along the Pacific coast of Mexico. The species distribute without an overlapping and have a similar, but distinctive, pattern of coloration. We also have made all species congeneric.
Lourenço, W. R., Laboratoire de Zoologie (Arthropodes), Muséum National d'Histoire Naturelle, 61 rue de Buffon 75005 Paris, France, and Cloudsley-Thompson, J. L., 10 Battshill Street, Islington, London N1 1TE, United Kingdom
Discovery of a sexual population of « Tityus serrulatus », alias the « confluenciata » form within the complex « Tityus stigmurus » (Thorell) (Scorpiones, Buthidae).
Tityus serrulatus Lutz & Mello, 1922 (in fact the form confluenciatawithin the « Tityus stigmurus » complex) is an extremely toxic scorpion of considerable medical importance in Brazil. Its rapid spread is partially due to parthenogenesis : speculation regarding the occurrence of sexual individuals has been resolved by the discovery of a population, described here, having a male-female sex-ratio of 1/2.5. Four color morphs of the « Tityus stigmurus » complex are also described and it is concluded that some described taxa are junior synonyms of T. stigmurus(Thorell, 1877).
Lourenço, W. R., Laboratoire de Zoologie (Arthropodes), Museum National d'Histoire Naturelle, 61 rue de Buffon 75005 Paris, France, and Cuellar, O., P.O. Box 17074 Salt Lake City, Utah 84117-0074, U.S.A.
A new all-female scorpion and the first probable case of arrhenotoky in scorpions.
A new parthenogenetic species of scorpion is reported from French Guyana based on the production of an all-female brood (thelytoky) by a wild virgin female. Conversely, the first probable case of male parthenogenesis (arrhenotoky) in scorpions is reported based on the production of two successive all-male broods by a wild caught virgin female of Tityus metuendus Pocock from Peru. Both species were found in isolated palm trees within the rain forest, conforming with the insular theory of parthenogenesis.
Lubin, Y., Mitrani Center for Desert Ecology, Blaustein Institute for Desert Research, Ben Gurion University, Sede Boker, Israel and Crouch, T., Durban Natural Science Museum, Durban, South Africa
Synchronized movement during prey capture in an African social spider, Stegodyphus dumicola(Eresidae).
The group-living spider Stegodyphus dumicola captures prey cooperatively: many individuals rush out toward a struggling insect caught in the communal, cribellate-silk web. The movements of spiders on the web when approaching the prey, during prey handling and while feeding appear synchronized and rhythmical, with alternating periods of movement and immobility. Synchrony could (1) enhance prey detection and localization by allowing spiders to discriminate temporally between their own web vibrations and those of the prey. Synchrony might reduce the risk of predation during activity on the web by (2) enabling spiders to detect the movement of potential predators or (3) by making it more difficult for a predator to focus on an individual spider. Finally, (4) synchrony may be an accidental outcome of conflicting demands to avoid attacking first on the one hand, and to obtain the best feeding site on the other, such that the behavior of each individual is determined by the behavior of its neighbors. For hypothesis (1) we predict synchrony during early stages of prey capture, but not later, in contrast with hypotheses (2) and (3). Synchrony combined with variable duration of immobility and movement periods are predicted by hypothesis (3). Hypothesis (4) predicts increased synchrony immediately preceding the first bite and during the initial stages of feeding, when conflict should be greatest. To test these hypotheses, we examined the movement of individuals and groups of spiders during prey-capture sequences in naturally occurring colonies.
Macias-Ordonez, Rogelio, Departamento de Ecologia y Comportamiento Animal, Instituto de Ecologia, A.C. Apartado Postal 63, Xalapa, Veracruz 91000, Mexico
Leg loss in the striped harvestman, Leiobunum vittatum (Say 1821) (Opiliones).
Many Opiliones rely on touch through their long legs to assess their environment. Appendotomy is a common phenomenon in Opiliones, which do not regenerate legs. Leg number in the striped harvestman has been shown to affect speed and fighting ability. In this study, I present a survey of leg appendotomy in 1630 individuals of a natural population of striped harvestmen over three years; in this population males fight over mating territories containing oviposition substrate, while females wander among territories mating and ovipositing repeatedly. Two out of three individuals were missing at least one leg. Legs from the second pair (much longer and used as probing organs while walking) are lost with much higher frequency than those of any other pair. The rate of appendotomy in adults (assessed through recaptures) suggested that most legs are lost during development. Leg loss was more frequent in females than in males. This and other comparisons of appendotomy patterns among sexes are discussed in the context of their mating system.
Main, Barbara York, Dept. of Zoology, University of Western Australia, Nedlands, Western Australia 6907
Notes on the biogeography and natural history of the orbweaving spider Carepalxis (Araneae, Araneidae) including a gumnut mimic from southwestern Australia.
The biogeography of the Gondwanan orbweaving spider Carepalxis L. Koch is reviewed. The genus occurs in Central and northern South America, Australia and New Guinea. It is newly recorded from Western Australia where it ranges from the tropics and arid interior to the mesic southwest. Mimicry by a southwestern Australian species of a jarrah gumnut (seed capsule of Eucalyptus marginata) is described and illustrated. The characteristic body form of Carepalxis, its retractile resting posture and modification of the abdominal "folium" pattern common to several araneid genera combine to give the gumnut resemblance. It is postulated that selection for this combination of features provides a defense against bird predators. Webweaving is briefly described. Seventy five percent of the Carepalxisspecimens in the Western Australian Museum were found in mud wasp nests. Spiders are rarely observed in the field due to their flimsy nocturnal web and cryptozoic daytime behavior. Nevertheless wasp predation suggests apparent rather than actual rarity.
SAMarshall, S. D. and Rypstra, A. L., Dept. of Zoology, Miami University, Oxford, OH 45056
Spider competition in structurally-simple ecosystems.
Interspecific competition among spiders has long been an elusive phenomenon for ecological study. Because most spider species are generalist predators, they should overlap in resource use wherever they overlap in space use and activity periods. However, despite the obvious potential for competitive interactions, empirical evidence for competition has generally been lacking. We summarize the results of four studies in which there was evidence of interspecific competition between spiders in wetlands ecosystems. Since this class of ecosystems has many similarities to row crops, including the relatively simple physiognomy of vegetation and cyclic disturbance regimes, these studies collectively suggest that it may be possible to uncover evidence for competition in row-crop agroecosystems. Our own work in a soybean agroecosystem also revealed competitive effects. We propose that spider competition may be more prevalent in structurally-simple habitats, where a few spider species occur in high densities. The lack of vertical stratification coupled with high population densities sets the stage for competitive interactions. Spider competition could potentially limit spider densities in agricultural ecosystems, which might in turn reduce their overall effectiveness as biological control agents.
Marusik, Yu. M., Crawford, R. and Eskov, K. Yu., Institute for Biological Problems of the North, Karl Marx Pr. 24, Magadan 685000, Russia
Spiders (Araneae) of the Kurile Islands: zoogeography.
More than 350 spider species were collected within Kurile Islands during the International Kurile Island Project and private trips (1994-1997). Preliminary notes on fauna of 22 visited islands are given. Distribution of species and infraspecific taxa within the Archipelago are discussed and a draft biogeographical subdivision of the Kurile Islands is proposed. Distributional pattern of spiders is compared with that of other invertebrate groups.
Mayntz, D. and Toft, S., Dept. of Zoology, University of Aarhus, Denmark
Growth and survival of Pardosa amentata fed fruit flies raised on media of different nutrient composition.
Previous studies have found that wolf spiders often die before they reach the adult stage when fed Drosophila melanogaster as the only prey. The wolf spider Pardosa amentata was used to test the hypothesis that prey quality is influenced by the nutrient value of the food that the prey has been reared on. Eight groups of spiders were fed wildtype Drosophila melanogaster as single species diets. The only difference between the groups was the culture medium in which the prey flies were cultured. Control flies were raised on pure Carolina Drosophila Medium Formula 4-24. Other groups were raised on the same basic medium with different additives: Vitamins, amino acids, methionine, fatty acids + sterols and dog food. There was a significantly higher survival of the spiders when the fruit fly medium had added amino acids, methionine or dog food. Growth was significantly higher in spiders when vitamins, amino acids, fatty acids + sterols or dog food were added to the basic fruit fly medium. To test the importance of nutrients in the gut content of the flies, two groups of flies were starved for 48 hours before being offered to the spiders - one reared without any additives and one with dog food addition. Gut content of the fruit flies had no effect on growth or survival of the spiders. These results demonstrate that prey quality is influenced by the quality of the food for the prey, and that the nutritional improvements are located in the tissues of the prey.
McClintock, Will, Dept. of Ecology Evolution and Marine Biology, University of California, Santa Barbara, CA 93106
The function of leg-waving behavior in male Schizocosa ocreata courtship.
Male wolf spiders, Schizocosa ocreata, wave their first pair of legs during courtship. Leg-waving behavior varies in synchronicity, or the degree to which the legs rise and fall in phase. I studied how variation in the leg-waving behavior of live males influenced female response. Conspecific females were quicker to respond to males with asynchronous (out-of-phase) leg-waving. This suggests asynchronony is more attractive and/or more conspicuous than synchrony. However, female sexual receptivity did not vary with leg-waving synchrony. This information alone suggests that the function of leg waving is to increase conspicuousness rather than sexual attraction. I also tested female response to computer animated male S. ocreata. As with live males, females were quicker to respond to animated males with asynchronous leg-waving behavior. However, none of the female S. ocreata displayed sexual receptivity in response to the computer animated males. Interestingly, some females of another species, S. rovneri, were receptive to animated male S. ocreata. Since male S. rovneri lack leg-waving behavior in courtship, yet female S. rovneri respond to leg-waving animated males, females may possess a residual or preexisting bias for this trait. These data are discussed in the context of a new model of sexual selection, the chase-away hypothesis.
Miyashita, T., Laboratory of Wildlife Biology, School of Agriculture & Life Sciences, University of Tokyo, Tokyo, 113-8657, Japan
Evidence for inter- and intraspecific competition in Argyrodes spiders.
Two species of kleptoparasitic spiders Argyrodes spp. often coexist on the same host web and occasionally reach high densities on the web. To determine to what extent inter- and intraspecific competition is important, I conducted removal experiments in the field. Removing A. flavescens from the host web induced rapid immigration of the same species and the density per web reached nearly half the level before the removal in only two days, while the density in control remained almost the same. This indicates that the density of A. flavescens was in near equilibrium state. Removing A. flavescensincreased the density of A. bonadea as well, and the rate of increase was correlated with the number of A. flavescens removed. This provides evidence for interspecific competition, a rare phenomenon in spiders. Based on these results, I will further discuss the importance of removal experiments for detecting interspecific competition when one species is in a near equilibrium condition.
Morse, D. H., Dept. of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912
Attack sites of newly-emerged crab spiders Misumena vatia (Araneae, Thomisidae) on their prey.
Newly-emerged, second-instar crab spiderlings Misumena vatia (Clerck 1757) attack small fruit flies Drosophila melanogaster on the head more frequently than predicted; based on the flies' surface areas of head, thorax, and abdomen; although a majority of attacks were directed to the large thorax and abdomen. This pattern did not change significantly during subsequent captures of flies. However, all of the spiderlings tested more than once attacked prey on more than one body part. Middle-instar Misumenaattacked small syrphid flies even more frequently on the head than did these second instars. This difference may result from a greater activity of the syrphid flies than the Drosophila.
SANyffeler, M., Zoological Institute, University of Bern, CH-3012 Bern, Switzerland
Prey selection in the field.
An overview of the general feeding patterns of common agroecosystem spiders is presented. Five groups of web weavers (Tetragnathidae, Araneidae, Theridiidae, Linyphiidae, Dictynidae) and five groups of hunters (small-sized Oxyopidae, large-sized Oxyopidae, Thomisidae, Salticidae, Lycosidae) are analyzed comparatively (based on 40 prey analyses previously published by various European and US authors). Less than ten insect orders and the order Araneae make up the great bulk of the prey of these spiders. Web weavers and hunters both basically feed in the same prey orders, but at different proportions. Web weavers are almost strictly insectivore (insects constituting > 99% of total prey). Hunters, however, exhibit a mixed strategy of insectivorous and araneophagic foraging patterns (insects constituting approx. 75-90% of total prey). The hunters demonstrate in general a less specialized feeding behavior (i.e., high diet breadth) than both the large and small web weavers. Overall, spider individuals of small size (including large percentages of immatures) numerically dominate the faunas of field crops, and these feed primarily on tiny prey organisms (< 4 mm in length). Field crops in western, central, and northern Europe are colonized predominantly by small soil surface-dwelling Linyphiidae and Lycosidae which feed primarily on small dipterans, aphids, and collembolans; similar feeding patterns of spiders had been observed in some agricultural fields in the northern US. The field crops of the southern US are in many areas colonized predominantly by hunters (i.e., Oxyopidae, Thomisidae, Salticidae) which feed largely on small heteropterans, dipterans, hymenopterans, homopterans, and spiders.
Ono, H., Dept. of Zoology, National Science Museum, 3-23-1 Hyakunin-cho, Shinjuku-ku, Tokyo, 169-0073 Japan
Spiders of the genus Heptathela(Araneae, Liphistiidae) from Vietnam, with notes on their biology and taxonomy.
From Vietnam two species of the genus Heptathela were hitherto known, that is, H. tonkinensis(Bristowe, 1933) recorded from Song Luc Nam and H. tomokunii Ono, 1997 recently described from Tam Dao by myself. During the entomological expedition to northern Vietnam made by the National Science Museum Tokyo from September to October 1997, some specimens of liphistiids were collected at Yen Bai and in Cuc Phuong National Park. After a taxonomical study of these materials, two new species were recognized. Some biological observations of the new species were made in the field. The trapdoor of a female (Yen Bai; body length 17.5 mm) was large (43x33 mm). The openings of some retreats (Yen Bai) were decorated with grass-blades. Some females carried egg cocoons with spiderlings, 120 (Cuc Phuong), 201 and 221 (Yen Bai) in number. Relationships between the species within the subfamily Heptathelinae are discussed, and the genus Heptathelais divided into four groups on the basis of the structure of female genitalia. The characteristics and the distributional range of each group are shown.
Opell, B. D., Dept. of Biology, Virginia Tech, Blacksburg, VA 24061
Changes in cribellum spigot number and cribellar thread stickiness associated with the origin of orb-weaving spiders.
A comparison of the cribella and cribellar prey capture threads of 13 species of spiders representing seven families confirms that the stickiness of a cribellar thread is directly related to the number of spigots on a spider's cribellum and, by implication, the number of cribellar fibrils that form this thread. This comparison also demonstrates that the origin of orb-weaving spiders was associated with increases in both the weight-specific number of cribellum spigots and the weight-specific stickiness of cribellar threads. In contrast to other cribellate spiders, the number of cribellum spigots of orb-weaving species of Uloboridae scales to spider mass. Thus, the origin of orb-weaving spiders involved not only behavioral changes that stylized and restricted the placement of cribellar threads, but also included morphological changes that increased the stickiness of these capture threads by endowing them with more cribellar fibrils.
Ovtsharenko, V. I., Dept. of Entomology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA
Biodiversity of the Australian ground spiders of the family Gnaphosidae: preliminary results.
The Australian gnaphosid fauna is extremely diverse with high levels of endemism, and is represented by more than 20 new endemic genera. Only one cosmopolitan genus Eilica, occurs in Australia where it is represented by 27 native species. Only a few introduced or cosmopolitan species of gnaphosids are found in Australia. The taxonomic structure of Gnaphosidae together with the position of some endemic genera are discussed.
Patoleta, B. and Zabka, M., Zaklad Zoologii WSRP, 08-110 Siedlce, Poland
Salticidae (Arachnida: Araneae) of islands off Australia.
Island faunas have been the subject for zoogeographical and evolutionary research for over a century, resulting in hundreds of papers, with the syntheses by MacArthur and Wilson being the most famous. Serious arachnological research on islands started some 60 years ago (Berland) and have been continued since then by Baert, Beatty, Berry, Brignoli, Gillespie, Jocqué, Lehtinen, Marples, Platnick, Prószyñski, Wanless, Zabka and many others. Amongst this literature only a few papers have dealt seriously with salticids, some of them based on incorrect taxonomic data. The present paper is a review of salticids representing 32 genera, collected sporadically on 36 islands off Australia. The majority of islands analyzed are of coral origin and are located along the NE coast of the continent. Special attention is given to the chain of Torres Strait Islands which form (or so we thought) the zone of faunistic exchange between Australia and New Guinea. The main aims of this research are: 1. To analyze the list of species (genera) in respect to their suspected geographic origin and total distribution. 2. To assess the dispersal abilities of the material studied. 3. To analyze the island faunas in relation to island age, geological origin, flora and human interference. 4. To predict the influence of Australian and other faunas on western Pacific islands. 5. To evaluate the role of Torres Strait Islands in faunistic exchange between Australia and New Guinea. Among analyzed taxa a few genera and species groups can be distinguished on their geographic origin, dispersability and present distribution.
Peng, Xianjin and Yin, Changmin, Dept. of Biology, Hunan Normal University, Changsha, Hunan, P.R.China, 410081
Some spiders of the family Salticidae (Arachnida, Araneae) from China.
The present paper deals with 13 species of the family Salticidae from China. 7 new species are described, as are 5 new to China. New to China: Ptocasius kinhi, Brettus albolimbatus, Hyllus lacertosus, Menemerus bivittatus and Neon ningyo. The female of Tasa davidi is newly described. Diagnostic structures, such as body and genital organ, are illustrated for each species. Descriptions and known data of geographical distribution also are given. In addition, detailed comparisons of each new species and its similar species are discussed. All type specimens are deposited in Department of Biology, Hunan Normal University, Changsha, Hunan, China.
Penney, D., Dept. of Earth Sciences, Williamson Bld., University of Manchester, Oxford Rd., Manchester, UK
Hypotheses for the Recent Hispaniolan spider fauna based on the Dominican Republic amber spider fauna.
The Dominican Republic amber fossil spider record is examined and hypotheses generated concerning the Recent Hispaniolan spider fauna which is, at present, poorly known. The families Cyrtaucheniidae, Microstigmatidae, Nemesiidae, Ochyroceratidae, Tetrablemmidae, Palpimanidae, Hersiliidae, Symphytognathidae s.l., Anapidae, Mysmenidae, and Hahniidae, known from the fossil, but not Recent fauna, are predicted to be components of the Recent fauna. Based on a terrestrial invertebrate species longevity of less than 15 million years, the presence of endemic and non-endemic species, and the assumption that Hispaniola has suffered no major ecological disruption that would cause the amber lineages to become extinct, the following hypotheses are made: Filistatidae and Desidae have colonized Hispaniola since the Miocene amber formation; Drymusidae, Amaurobiidae, and Deinopidae were present on Hispaniola during the Tertiary, but avoided capture in the amber-producing resin; and Scytodidae, Oecobiidae, Uloboridae, Dictynidae and Clubionidae have colonized Hispaniola since the Miocene amber formation but these families, which were present on Hispaniola during the period of amber formation, contain undiscovered endemic species.
HPPerez-Miles, F., Seccion Entomologia, Facultad de Ciencias, Igua s/n esq. Mataojo, 11400 Montevideo, Uruguay
A phylogenetic analysis of Theraphosinae (Araneae, Theraphosidae).
An updated phylogenetic analysis of the Theraphosinae is performed taking Raven (1985) and Perez-Miles et al. (1996) as the starting point. Most genera were represented by the type species and/or one or more species. Chromatopelma Schmidt 1995, and PseudohapalopusStrand 1907 restored by Schmidt (1991,1997) were not included because types were not available for study. The holotype female of BrachypelmidesSchmidt 1994 is not available, but a male identified by Schmidt was examined and does not differ from Brachypelma. Thrixopelma Schmidt 1994 was included based on data taken from literature, although the type is not available. The monophyly of the Theraphosinae is supported by the following synapomorphies: i) extended subtegulum, ii) keels on palpal bulbs, iii) type III of urticating hairs (with some reversions) and iv) unilobular spermathecae (at least in each side). Types I and IV of urticating hairs seem to be synapomorphic of some genera within Theraphosinae. Although types and congeners from Aviculariinae, Harpactirinae and part of Ischnocolinae were selected as outgroup, Aviculariinae seems to be the sister group of Theraphosinae. Both taxa share defensive abdominal movements (related with the occurrence of urticating hairs), not known in any other theraphosids. Three trees of maximum fit (131.5) and 79 steps were obtained using Pee-Wee (version 2.5.1) and the strict consensus tree of them is presented.
Persons, M. H., Dept. of Biological Sciences, Union College, Schenectady, NY 12308 and Uetz, G. W., Dept. of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221
Do conspicuous ornaments influence sexual cannibalism in wolf spiders?
We examined the relative influence of a secondary sexual characteristic on female predatory behavior and mate choice. Males of the brush-legged wolf spider Schizocosa ocreata (Hentz) have ornaments in the form of tufts of bristles on the first pair of legs. Male and female spiders were randomly paired in containers equal to the daily home range size of adult females (N = 120). Tuft area and asymmetry were measured and mating success and/or cannibalism of males were recorded. Larger tufted males had greater mating success and were less likely to be cannibalized by virgin females. When males were paired with previously mated females, large tufted males again had less cannibalism risk but were no more likely to receive second matings than small tufted males. Tuft asymmetry was predictive of cannibalism risk, but not mating success. Results suggest that male tuft size may be maintained via both natural selection through cannibalism inhibition and sexual selection via mate choice but that tuft symmetry is maintained by natural selection alone.
Piel, W. H., Museum of Comparative Zoology, 26 Oxford Street, Cambridge MA 02138
The orb web as a force for stasis: homogeneity and convergence in the genus Metepeira (Araneae, Araneidae).
If one could rewind the course of time for an evolving lineage, would history repeat itself? Species in the genus Metepeira are fairly homogeneous, and often even cryptic. Most notably, they spin a unique type of orb web, share similar patterns and coloration, gravitate to extreme environments, often live in communal colonies, and frequently show large intraspecific variation in male size. Is this homogeneity because of scarce opportunity to evolve differently, or because of a tendency to gravitate to similar evolutionary outcomes? If the former, it follows that when history is rerun a new opportunity to evolve might lead to a very different outcome. If the latter, a new opportunity would not result in a different outcome. An examination of the phylogenetic relationships among Metepeira species suggests that Caribbean/Central American coastal species led to at least four independent radiations in North and South America -- equivalent to replaying history four separate times. Yet each of these radiations resulted in similar outcomes through parallel and convergent evolution and a gravitation to similar, extreme environments. I argue that Metepeira's most innovative feature, its unique orb web, has constrained the evolution of its descendants and encouraged convergence to a similar suite of morphological, ecological, and behavioral characteristics.
Pinto-da-Rocha, R., Museu de Zoologia, Universidade de Sao Paulo, Caixa Postal 42694, Sao Paulo, SP 04299-970. Financial support: FAPESP
Cladistic analysis and systematic review of the subfamilies Caelopyginae, Progonyleptoidellinae and Sodreaninae (Opiliones: Gonyleptidae).
The harvestmen Caelopyginae Sorensen, 1884 (9 genera, 28 species here proposed), Progonyleptoidellinae Soares & Soares, 1985 (9, 17) and Sodreaninae Soares & Soares, 1985 (3, 5) were recorded from the Brazilian Atlantic Rainforest from Bahia to Santa Catarina States. A cladistic analysis was performed with Hennig86 program, using mh* and bb* algorithms. These three subfamilies form a monophyletic group based on: pedipalpal femur slender and cylindrical; pedipalpal tarsus biconvex with two rows of short and thick setae. Two analyses were performed, one for species of the Caeloyginae and other for those of Sodreaninae and Progonyleptoidellinae (40 characters). The generic classification of all subfamilies changed after the results of cladistic analyses. Sodreaninae is monophyletic based on pedipalpal femur and patella lengthened and dorsal scute groove with white patches. Progonyleptoidellinae and Caelopyginae share a high number of articles on tarsi I and III-IV, semi-spherical shaped tarsi III-IV and distitarsi II with 4-5 articles. Caelopyginae has 9 synapomorphies as the claws III-IV pectinate, eye mound wide and depressed, with two tubercles and dorsal and ventral anal opercula with white patches. The possible synapomorphy of Progonyleptoidellinae, coxa IV hidden dorsally by dorsal scute, probably has arisen in the ancestral of this subfamily plus Caelopyginae (reverting to ancestral condition in the second) and both can be synonyms.
HPPlatnick, N., Dept. of Entomology, American Museum of Natural History, Central Park West at 79th Street, New York NY 10024
The Limits of Lamponidae (Araneae).
No abstract submitted.
Pollard, Simon, D., Canterbury Museum, Rolleston Avenue, Christchurch 8001, New Zealand and Jackson, Robert, R., Dept. of Zoology, University of Canterbury, Christchurch, New Zealand
Palp friction: sexual selection and foraging costs.
Portia fimbriata is a cryptic, araneophagic salticid which stalks and catches cursorial salticids. Stalking depends primarily on concealment, but male P. fimbriata were less effective at catching salticids, compared to conspecific females. Because the males' palps, being gonopods, are considerably enlarged compared with the females' palps, they appear to reveal the spider as a predator to their visually competent prey. In experiments, where the males' palps were removed, their capture efficiency became indistinguishable from that of females. While the males' palps also have conspicuous hairs and markings (secondary sexual characters), juvenile males, which have enlarged palps, but not secondary sexual characters, were also less effective than females at catching salticids. Primary sexual characters are not usually exaggerated sufficiently to have costs comparable to those of secondary sexual characters. However, a combination of the spider's method of sperm transfer, the relation of intersexual selection in salticids to visual displays, and the acute vision of both the predator and its prey appears to have resulted in a unique adaptive trade-off in male P. fimbriata.
Popson, M., Dept. of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, and Jakob, E. M., Dept. of Entomology, University of Massachusetts, Amherst, MA 01003
Learning in Phidippus audax (Salticidae).
There has been a recent surge of interest in insect learning, but the role of learning in the lives of spiders has not been well studied. We present three tests concerning learning in Phidippus audax (Salticidae). (1) We tested whether spiders could learn to return to the location where they had successfully captured prey. A housefly was hidden behind one of two barriers in opposite arms of a T-maze. Spiders reached the prey faster after four training trials (Wilcoxon signed rank test, z = -2.58, p < 0.01, N = 30). In a test trial in which no prey were present, the time taken for spiders to look behind the correct barrier did not differ from the 4th training trial, indicating that spiders learned locational cues and were not simply responding to cues from the prey (z = -0.56, P > 0.5). (2) We investigated whether spiders could associate particular colors with prey with a radial maze with red and blue landmarks in opposite arms. Spiders were trained to associate food with one of the colors, and reached the correct landmark faster after four training trials (z = -2.30, P < 0.03, N = 30). In a test trial with no prey, the time to reach the correct landmark did not significantly differ from the 4th training trial (z = 0.69, P > 0.4). (3) We examined a possible ecological context in which learning may be important. In a terrarium, spiders were likely to reuse nests rather than build new nests (chi-square = 12, p < 0.0001), suggesting that the ability to learn locational cues may be adaptive.
Powers, K. S., Dept. of Ecology and Evolutionary Biology, University of Arizona in Tucson, AZ 85721, and Bukowski, T. C., Dept. of Psychology, Tulane University in New Orleans, LA 70118
Seasonal variation in prey selection of a spider-hunting wasp Chalybion zimmermani (Hymenoptera: Sphecidae).
Females of the predator wasp Chalybion zimmermani (Hymenoptera: Sphecidae) provision their young with a variety of spider prey. Previous studies suggest that spider-hunting sphecid wasps change their foraging preferences throughout their breeding season in response to seasonally varying prey communities. We conducted a study in southeastern Louisiana to assess seasonal changes in the types of spider prey available to wasps and how wasps respond to these changes. Over a nine week period of the wasps' breeding season we recorded the species, age, sex, and length of all nonsocial web-building spiders along transects surrounding a wasp nest site. Concurrently, we recorded the same characteristics of spiders selected by wasps. Comparisons between characteristics of available and selected prey revealed that species, age, and sex of prey selected by wasps were dictated mainly (but not entirely) by prey abundance and the prey size. Because the abundance and sizes of spiders within the prey community changed over the nine week period, the species of prey collected by wasps also changed. The influence of each of these characteristics and their combined effect on wasp prey preference will be discussed.
Prendini, Lorenzo, Percy FitzPatrick Institute, University of Cape Town, Rondebosch, 7701, South Africa
Phylogeny of the superfamily Scorpionoidea Peters 1861 (Chelicerata: Scorpiones).
Stockwell (1989) proposed a cladogram and revised classification for the superfamily Scorpionoidea Peters 1861 (comprising the families Bothriuridae, Diplocentridae, Heteroscorpionidae, Ischnuridae and Scorpionidae) based on a cladistic analysis of 43 morphological characters and 35 taxa. However, Stockwell attained limited cladistic resolution below the familial level, which may be partially attributed to his use of terminal 'pseudotaxa' for representing genera whose monophyly was implicitly assumed. Consequently, Stockwell's findings have limited utility for lower level investigations of scorpionoid phylogeny and the confidence with which his revised classification can be adopted is questionable. A re-investigation of scorpionoid relationships is presented here, based on 115 morphological characters, including those used by Stockwell, and 71 species. The approach adopted differs from Stockwell's in that each genus is represented by at least two exemplar species rather than a 'pseudotaxon'. The analysis is aimed at testing the monophyly of the scorpionoid families and subfamilies, at resolving relationships among putative genera, and at resolving relationships among the major clades within the superfamily. The results of unweighted parsimony analysis, analysis with successive approximations character weighting and analysis with implied character weighting are compared with the findings of Stockwell (1989) and previous workers, and revisions to the existing classification are proposed.
Prószynski, Jerzy, Muzeum i Instytut Zoologii PAN, ul. Wilcza 64, 00-679 Warszawa, Poland
Presentation of the "Salticidae: Diagnostic Drawings Library" project (Internet http://spiders.arizona.edu/diagnost/title-pg.htm and computer disk).
The Library now contains diagnostic drawings of about 1100 species of Salticidae, mainly from Palaearctic and Oriental Regions, also part of Ethiopian, Australian and Oceanian genera of Salticidae. It was originally planned as a collection of drawings of single representative species of each genus. However, now some genera are fairly complete; we plan to include within a few years drawings to ALL species illustrated in the world literature. We intend to establish interactive connection with world Catalogue of Salticidae (updated version, current one http://spiders.arizona.edu/proszynski/proszynski.html), permitting instant switching from drawings of a species to its Catalogue data, and from Catalogue to drawings. Special feature of the Library are analytical pages, like lists of fauna of particular countries, hyperlinked with drawings of species concerned; currently available for Poland, former USSR, Israel, Arabian Peninsula, Vietnam, Philippines and for genera of Indonesia and Pacific Islands; more lists will be added. There is also an interactive Key to Salticidae of Israel. Library contains also color photographs of some species and descriptions of new taxa. The library can serve a variety of purposes: instant comparison of related species, drawings of the same species by various authors and facilitate a variety of research ideas. The presentation will be illustrated by color slides and a demonstration of actual work on a computer on Thursday evening, see program.
HPRamírez, M. J., Laboratory of Arthropods, Dept. of Biology, FCEyN, Universidad de Buenos Aires, Pabellón II Ciudad Universitaria (1428) Buenos Aires, Argentina, and Museo Argentino de Ciencias Naturales, Av. Angel Gallardo 470 (1405)
Respiratory system morphology and the phylogeny of haplogyne spiders (Araneae, Araneomorphae).
The morphology of the respiratory system of basal araneomorph spiders, the Haplogynae, and Entelegynae with female haplogyne genitalia is reviewed. The homology of cuticular respiratory structures are discussed in the light of their connection with abdominal muscles and ontogeny. The morphological data were coded in 8 characters (18 states), mainly from posterior pulmonary (or tracheal) segment, and 7 non-respiratory characters added. The new data were combined with those of a previous analysis made by Platnick et al., in a data matrix of 80 characters scored for 44 terminals, intended to include all available characters. The parsimony analysis under implied weights confirmed and strengthened that previous analysis. The evolution of the tracheal system is traced through the phylogeny of basal spiders and the Haplogynae, and new synapomorphies are provided. Elongate 3rd abdominal entapophyses are a synapomorphy of Araneomorphae. True median tracheae are a synapomorphy of the Entelegynae --convergently with Austrochilinae-- as well as the extreme posterior displacement and narrowing of tracheal spiracle. Pholcidae, Diguetidae, and Plectreuridae are united by the absence of tracheae, diguetids and plectreurids by the further absence of the corresponding entapophyses. Scytodidae, Sicariidae and Drymusidae are united by the fusion of 3rd entapophyses.
Raven, Robert J., Queensland Museum, PO Box 3300, South Brisbane, 4101, Q. Australia
Revision of the Australian genera of the Miturgidae with a preview of their relationships.
The Australian Miturgidae are revised to include Miturga, Diaprograpta, Uliodon and 6 new genera. Males of all lack a tibial crack and interlocking tegular lobes. The synapomorphy of this group is a large unsclerotised area on the tibial apophysis, also found in many Anyphaenidae. Males of a putative sister genus of the blind Janusia resemble the African Phanotea in having interlocking tegular lobes but lack a tibial crack. Two other new miturgoid genera share with Griswoldia (Griswoldiinae, formerly Machadoninae) the presence in males of a tibial crack but both lack interlocking tegular lobes. The phanoteine and griswoldiine genera show no close relationships with Australian Miturgidae. A new character, the retrocoxal window (RCW), is a weakness centrally on the retrolateral face of the coxa I of miturgoids, many zorids, most corinnids, and some clubionoids but absent in many gnaphosoids.
Rayor, L. S., Dept. of Entomology, Cornell University, Ithaca, NY 14853, and Uetz, G. W., Dept. of Biological Sci., University of Cincinnati, OH 45221
Age-related preemptive web-building as an adaptive spacing strategy in the colonial spider Metepeira incrassata (Araneidae).
Colonial orb web-building spiders provide insight into the proximate mechanisms by which social animals space themselves within a group. We examine web building patterns in Metepeira incrassata and experimentally test mechanisms for the observed patterns. Metepeira are diurnally active spiders which construct new orb webs each morning. Larger webs require more space: web size increases with spider size, and construction time increases with web size. Our observations demonstrate that Metepeira exhibit a characteristic sequence of web building, with larger spiders completing their webs significantly earlier than individuals of smaller size-classes. We propose the Preemptive Web Building hypothesis to explain that to assure sufficient space for their orb webs, larger spiders build earlier in the day to preempt the necessary space within the colony. In experiments, the presence of large spiders tended to inhibit the web building of smaller individuals. However, disturbances during web construction significantly delay the completion of the web, and precipitate movements to new web sites. One prediction of our hypothesis - that spatial needs translate into earlier building - was confirmed by significantly earlier web building by mature females with egg sacs (which are unable to move their egg sacs) compared to same sized females without eggs (which can change locations freely). Preemptive web-building is a proximate mechanism that influences spacing among colonial orb weaving spiders and helps shape the typical hierarchical size-distribution of spiders within the colony.
Relys, V., Dept. of Zoology, Vilnius University, Ciurlionio str. 21/27, Vilnius, LT - 2009, Lithuania
Alpine endemic species in the epigeic spider communities in the Eastern Alps.
The alpine-endemic species of spiders are important and interesting not only from a historical or zoogeographical point of view. Most of them are common and important members of epigeic spider communities. The alpine-endemic species from the epigeic communities were investigated at 90 localities in different regions of Austria, Switzerland and Italy. All localities are situated at altitudes over 1000 m. Only spider communities investigated by means of pitfall traps and represented by more than 20 species and 250 specimens have been analyzed. In most communities, the alpine-endemic species are represented by fewer than 10 species and usually make up 20 -30% of all the species in the community. The part of the specimens belonging to the alpine-endemic species shows higher variations (15 - 80%). Such situation is caused by high dominance of some dominating lycosid species. There are not very high differences in the endemic parts of the epigeic spider communities in the northern (Austrian) or southern (Italy) sides of the Alps. According to the results of cluster-, DCA and MDS-analysis, the groups of alpine endemic species typical for open sites of the low-alpine, high-alpine zones as well as for woodland areas may be separated. The zoogeographical separation of endemic parts of the epigeic spider communities in Eastern Alps seems to be difficult.
Ribera, C. and Arnedo, M. A., Departament de Biologia Animal, Universitat de Barcelona, Av. Diagonal, 645, 08028 Barcelona, Spain
The dark side of an insular specific radiation: the troglomorphic Dysdera (Arachnida, Dysderidae) species from the Canary Islands.
The lava tubes in the Canary Islands hold an unusually rich troglomorphic fauna for an oceanic archipelago. Spiders are an important component of this fauna, the genus Dysderabeing one of its most diversified groups. Dysdera has undergone a radiative process in the Canarian Archipelago and is represented by 43 species, 8 of which (18,6%) display different degrees of adaptation to the hypogean environment. Results regarding adaptation to the volcanic hypogean environment in the light of their phylogeny are presented. Emerging biogeographic patterns as well as character evolution are discussed. Cave-dwelling species are usually parapatric in relation to their closest relatives. This suggests that extinction of epigean populations is not a necessary condition for speciation and that these troglobitic species can not be considered in any way as 'relicts'. Morphological adaptation to caves, with the exception of D. unguimmanis, is almost exclusively manifested as eye reduction, and in a few cases with a certain elongation of the walking legs. Lack of strongly adapted morphological characters could suggest that adaptation to volcanic underground environment in canarian Dysdera is mainly shown as physiological and/or behavioral traits. There is no evidence for a close relationship between level of troglomorphism and time of divergence. Some 'old' troglobites show a lower degree of troglomorphism when compared to some recently diverged taxa.
Richman, D. B., Dept. of Entomology, Plant Pathology and Weed Science, New Mexico State University, Las Cruces, NM 88003
Flea beetle mimicry in jumping spiders - a review.
The jumping spiders include a number of remarkable mimics of venomous insects. Probably the most well known are the ant mimicking genera, such as Synemosyna, Peckhamia, Synageles, Myrmarachneand Sarinda. Also, some species of Phidippus, such as P. apacheanus Chamberlin and Gertsch, apparently mimic the venomous velvet ants in the genus Dasymutilla. Ant mimics have been reasonably examined, although much remains to be done in this area, and Edwards has initially examined velvet ant mimicry in Phidippus. While flea beetle mimics in the genera Agassa, Sassacus, Cylistella, and Coccorchestes have been known for some time now, the biology and behavior of beetle mimics is little understood. It is possible that many metallic species of salticids may be facultative flea beetle mimics, in addition to those that are structurally beetle-like. Preparatory to a revision of Agassa, Sassacus, and the possibly related, but less beetle-like, "Metaphidippus" vitisgroup, it was necessary to review the subject of flea beetle mimicry and to offer some possible hypothesis as to the evolutionary development and advantage of this unusual mimicry.
SARiechert, S. E., Dept. of Ecology & Evolutionary Biology, University of Tennessee, Knoxville TN 37996-1610
The hows and whys of successful use of spiders in biological control programs.
It is clear from spider performance in natural communities, that they can have significant limiting influences on their prey. From study of the mechanisms by which spider populations influence prey, we can identify agricultural systems in which they might best be applied as agents of biological control. Theory predicts that prey control is achieved through a stable interaction between predator and prey populations. This can be achieved through two mechanisms, limit cycle and equilibrium point control. Limit cycle control has received the most attention in agroecosystems, but with their long life cycles and generalist feeding, spiders are a relatively poor fit for this type of control. Crops with short growing seasons and species depauperate systems are the best candidates for limit cycle influences of spiders on prey. Equilibrium point control, on the other hand, is best achieved through conservation of spider diversities. Systems that require minimal chemical application and where some type of ground cover is maintained are good candidates for equilibrium point control. It is also important to recognize that many success stories in agroecosystems deviate from stable equilibrium conditions. Indirect effects (e.g., the cessation of feeding in the presence of a predator) and superfluous killing of prey are two factors that might augment the influence of spiders on targeted insect populations. Biological control successes with spiders may also come from a very different approach, the use of components of their venoms in a new class of chemical pesticides.
Riecken, U., Federal Agency for Nature Conservation, Mallwitzstraáe 1 - 3, D-53177 Bonn, Germany
Effects of short-term sampling on ecological characterization and evaluation of epigeic spider communities and their habitats for site assessment studies.
Epigeic invertebrates like spiders and carabid beetles play an increasing role for habitat characterization and assessment within several types of environmental planning projects in Germany and other European countries. Due to the rather high costs for sampling spiders e.g. by means of pitfall traps, proposals for limiting sampling efforts are required for practical use. Comparing the results, applying different proposals for limiting sampling, to those from continuous catches over a two year period, it was the aim to find out what implications short term sampling and a reduced number of traps have. Decreasing sampling effort generally correlates with an increasing failure, both in number of recorded species and in ecological characterization of species composition. Finally conclusions for the use of epigeic spiders as indicators within future environmental plannings are discussed.
Rivera, M., Zoology Dept., University of Hawaii. Honolulu, HI 96822
Morphological and molecular diversity in Hawaiian Argyrodes (Theridiidae).
Endemic spiders of the genus Argyrodes represent one of many diverse radiations of Hawaiian arthropods. Two distinct species groups within the genus are found in Hawaii, each with different foraging modes and morphologies. One group (A. argyrodesgroup) is kleptoparasitic in the large sheet webs of another native spider lineage. The other group (Ariamnes-Rhomphaea) is generally free-living, although some species are kleptoparasitic. Genetic analysis of 473 bp from the mitochondrial gene Cytochrome Oxidase I suggest separate colonization events for these two groups. Analysis of COI also shows that the kleptoparasitic A. argyrodes are relatively divergent, showing up to 9% genetic distance between morphospecies, yet the few species in the lineage have remained similar in morphology. The level of genetic differentiation between morphospecies also suggests that the Hawaiian A. argyrodes are relatively old. Conversely, COI analysis of the Ariamnes-Rhomphaea group reveals that these species are much less divergent, with only up to 5% genetic distance between morphospecies, yet the lineage is much more speciose and exhibits a wide range of morphological diversity. These results suggest that, despite their greater age, the A. argyrodes species have diversified little, possibly as a result of environmental constraints of their host association. In contrast, representatives of the younger Ariamnes-Rhomphaea group have diversified rapidly in terms of number of species and morphology, and may represent a true adaptive radiation driven by the exploitation of new feeding niches.
SARypstra, Ann L., Dept. of Zoology, Miami University, 1601 Peck Blvd. Hamilton, Ohio 45011 USA
Architectural modifications of agricultural habitats and their impact on the spider inhabitants.
The density and diversity of the spider community has been closely tied to the structural complexity of the local environment. For instance, soil dwelling spiders increase dramatically when the litter layer is enhanced because there are more retreats and hiding places and because temperature and humidity extremes are moderated. Web-building spiders are directly linked to the configuration of the vegetation because of specific web attachment requirements. Both correlative and experimental data support a tight relationship between spider density and habitat structure. Most of the available data show that agricultural practices which enhance the structural complexity of the environment (such as intercropping, mulching, and conservation tillage practices) enhance the density and diversity of the spider community. The key question regarding spiders in agroecosystems is, of course, whether they are in any way suppressing the activity of herbivores. Although some studies uncovered a strong link between habitat complexity, spider abundance and plant productivity, not all studies have been able to find a relationship between spider abundance and herbivory. In addition, the specific mechanisms by which spiders exert their top-down effect have, thus far, proven elusive. More investigation into the specifics of how habitat structure influences the predator - prey interactions in agroecosystems is needed in order to truly understand and manage agricultural production in a responsible manner.
SASamu, F., Dept. of Zoology, Research Institute for Plant Protection, Hungarian Academy of Sciences, Budapest, P.O.B. 102, H-1525, Hungary., Sunderland, K. D., Horticulture Research International, Wellesbourne, Warwick CV35 9EF, U.K., and Szinetár, Cs., Berzsenyi College, 4 Károlyi Gáspár Sqr., Szombathely, H-9700 Hungary
Scale-dependent distribution patterns of spiders in agricultural systems: a review.
A conceptual framework is presented for the study of the factors affecting the distribution and abundance of spiders in agricultural systems. It is useful to consider how factors operate at three levels of a spatial hierarchy, namely micro-habitat, habitat and landscape. The size and distribution of spider populations are determined by factors influencing survival, reproduction and dispersal. Modes of dispersal vary in terms of the efficiency of sampling new habitats and the level of risk. A literature survey of proximal factors (micro-climate, habitat structure, disturbance, prey availability, predation, cannibalism and territoriality) affecting micro-habitat usage by spiders showed that the relative importance of these factors varied according to spider species. Abiotic factors were demonstrated to have a significant effect more frequently. Spider abundance and diversity were found, in general, to be positively correlated with environmental diversity at different spatial scales. Within-field habitat diversifications were found to be more effective in increasing spider populations when interspersed throughout the crop (e.g. polycultures and reduced tillage) than when spatially segregated (e.g. strip management). At the landscape level, opportunities were identified for increasing regional populations of spiders, and optimising pest control, by management of the annual shift in the crop mosaic to maximize spider transfer rates from senescing crops to young crops.
Schmidt, G., Von-Kleist-Weg 4, D-21407 Deutsch Evern, Germany
A theraphosid spider from the island of Negros (Philippines).
Negros, the fourth largest island of the Philippines, is situated between Panay, Zebu and Mindanao. Records about theraphosid spiders are known from no one of these islands in the past. The species found on the Philippines belong to 3 genera of the subfamily Selenocosmiinae: The large Orphnaecus pellitus Simon, a cave--dweller, and the 2 smaller species Phlogiellus baeri (Simon) and P. insularis (Simon), living on the island of Luzon, the large Chilocosmia samarae (Giltay) and the small P. mutus (Giltay). living on the island of Samar. The first theraphosid spider from Negros is very closely related to C. samarae and C. dichromata (Schmidt & von Wirth), living on Western Papua New Gui-nea. It differs from C. samarae in body size, scopula of metatarsus IV and a thickened tibia and metatarsus IV and from C. dichromata in different eye position and a different relation between AME and ALE. Metatarsus IV is not thickened in C.dichromata. In the new species leg IV is very long. The spermatheca consists of 2 simple separate receptacula seminis not diverging (difference from C. arndsti (Schmidt & von Wirth)). The AME are as large as the ALE (difference from C. arndsti and C. dichrornata). The genus Chilocosmia seems to be distributed from the Philippines to Papua New Guinea.
Schmidt, Justin O., Southwestern Biological Institute, 1961 W. Brichta Dr., Tucson, AZ 85745, USA
Courtship, female choice and male investment in the vinegaroon, Mastigoproctus giganteus.
The objects of this investigation were to characterize the courtship behavior and to evaluate the roles of female choice and male investment in the vinegaroon (Uropygida: Thelyphonidae: Mastigoproctus giganteus). In the study area, a high desert sandy grassland near Willcox, AZ, mating takes place during the summer rains. In Autumn, each female constructs a cell ca 50 cm deep in the soil, and therein produces an egg mass the next May or June. Courtship consists of four distinct phases: 1) chase and grapple; 2) dancing; 3) spermatophore generating; and 4) pressing the spermatophore into the gonopore. The four phases of courtship require on average 13 hours (n=9). Females exhibit profound mate choice and often physically resist and reject undesired males (n=21 acceptances; 14 rejections). Females may reject several males before accepting one found suitable. Both males and females can mate more than once, though the frequency in nature of female multiple matings is unknown. Males invest considerably in the courtship process: they produce a 23 mg spermatophore (n=1) which requires on average 4 hours to generate (n=13), and they lose a day's foraging during the courtship. Males sometimes will refuse to court willing females.
Schmidt, Justin O., and Schmidt, Li S., Southwestern Biological Institute, 1961 W. Brichta Dr., Tucson, AZ 85745, USA
Ecology and population biology of the vinegaroon, Mastigoproctus giganteus.
Vinegaroons are typically considered to be rare and obscure. Our goals were to determine the fundamental ecology and biology of the vinegaroon in its natural habitat. A 2.56 Ha study plot was divided into 10 x 10 m subplots and vinegaroons within were located, measured, sexed, marked and released. Because recapture rates did not exceed 15% or tend to asymptote, exact population estimates and home territories could not be determined. Nevertheless, the density of large individuals (third & fourth instars and adults) in the plot appears to be about 100 per hectare. Average distances moved between captures were: males -- 54 m; females -- 14 m; fourth instars -- 12 m. Thus, although home ranges can be fairly large for this species, males clearly have much larger ranges than others. Between season, the ratios of males:females did not change, but the ratios of adults to immatures varied dramatically. The main limiting factor in the ecology and biology of vinegaroons is prey shortage. Predation on large individuals appears nil and, contrary to some preconceptions, cannibalism appears irrelevant and was never observed in the field or in natural laboratory conditions.
Schütt, Karin, Museum fuer Naturkunde, Institut fuer Systematische Zoologie, Invalidenstr. 43, D-10115 Berlin, Germany
The triad - an apomorphic character of the Araneoidea?
The triad is a functional unit consisting of three silk glands, which lead into the distal half of the posterior spinnerets. The slender spigot of the glandula flagelliformis is surrounded by two spigots of the glandulae aggregates. The former gland supplies the core fibre thread, on which the glue is spread by the latter glands. Both the triad and the gluey capture thread are supposed to represent apomorphic characters of the Araneoidea. The homology of the flagelliform gland of the Araneoidea and the pseudoflagelliform gland of the Deinopoidea is one main argument (apart from the orb) for the monophyly of the Orbiculariae. In this study I examined the spinnerets of 60 species belonging to 17 spider families with SEM. In most species I have studied both sexes and in some species different developmental stages, too. A reduction of triads occurs not only in specialized predators, but also in sheet-web weaving linyphiids. The triad as a functional unit does not exist in theridiids and theridiosomatids. In some families the triad is kept in adult males dependent on body size. The monophyly of the Orbiculariae, the homology of orb-webs, and the origin of the triad is discussed.
Selden, Paul A., Dept. of Earth Sciences, University of Manchester, Manchester M13 9PL, UK, and Shear, William A., Dept. of Biology, Hampden-Sydney College, Hampden-Sydney, VA 23943
Attercopus: new data on the oldest spider, and the origin of spinnerets in the Araneae.
The oldest known fossil spider, Attercopus fimbriunguis (Shear, Selden & Rolfe, 1987), from middle Devonian (382Ma) strata of Gilboa, New York, was described as sister taxon to all other spiders (on the basis of the structure of the walking leg Pa-Ti joint). Attercopus shares the plesiomorphic character state of spinneret tartipores absent with Mesothelae. New material collected in 1993 from slightly younger (374Ma) rocks at South Mountain, New York, represents at least three individuals (based on a chelicera count), which appear to be conspecific with A. fimbriunguis. Two specimens show cuticle which bears silk-gland spigots. Reviewing the sparse data on Attercopus spinning organs, all specimens show a single, simple spigot type, no tartipores, and spigots arranged in a curved row of up to two wide, apparently along the edge of a plate-like appendage. That the spigots do not occur on an obvious spinneret with subcylindrical podomeres needs explanation. Three hypotheses are discussed: (1) the spigots are male epigastric gland spigots at the anterior edge of the epigastric furrow; (2) the spinnerets in Attercopus are broad and plate-like; and (3) the spigots are arranged along the posterior edges of ventral abdominal plates (cf. book-lung opercula). It is possible that the Attercopus spinning apparatus is in a more plesiomorphic condition than in other spiders, but a firm conclusion cannot yet be drawn.
Shultz, J. W., Dept. of Entomology, University of Maryland at College Park, College Park, MD 20742
Phylogeny of Opiliones (Arachnida): an assessment of the `Cyphopalpatores' concept.
Opiliones has typically been divided into three suborders (Cyphophthalmi, Laniatores and Palpatores), but this system has been challenged in recent years. Based on scenarios of genitalic evolution, Martens and coworkers have argued that certain lineages within Palpatores are more closely related to Cyphophthalmi than to other palpatorean opiliones and erected a new clade, Cyphopalpatores, to accommodate this proposal. However, this system is also problematic. Because most genitalic characters within Opiliones are unique to that order, genitalic characters cannot be polarized and opilionid phylogeny cannot be rooted using objective outgroup comparison. Thus the Cyphopalpatores concept rests heavily on speculative scenarios of character evolution. The goal of the present study was to examine relationships among the major lineages of Opiliones using both genitalic and non-genitalic characters and thereby assess the Cyphopalpatores concept and associated scenarios of genitalic evolution. Maximum-parsimony analysis of a matrix composed of 17 terminal taxa (including two outgroups) and 25 binary and multistate characters recovered a minimal-length topology that was incompatible with the Cyphopalpatores concept but suggested that Cyphophthalmi is the sister group to a clade comprising a monophyletic Palpatores and monophyletic Laniatores. In contrast, the most-parsimonious distribution of characters within the minimal-length topology supported many of the character transformation series upon which the Cyphopalpatores concept was based. This result reaffirms the observation that a given hypothesis of character evolution can be consistent with several phylogenetic hypotheses and that an empirically robust phylogenetic analysis should include more than one character system.
HPSilva Davila, Diana. Dept. of Entomology, American Museum of Natural History, Central Park West at 79th St., New York, NY 10024
A phylogenetic approach to ctenid classification (Araneae, Ctenidae).
The monophyly of the spider family Ctenidae has been refuted recently. Additionally, it is currently hypothesized that Phanotea and Griswoldiatogether represent the sister group of ctenids and belong in the ctenoid complex of the Lycosoidea. However, there is still a need for a more comprehensive study involving most, if not all, known genera of the family and other taxa once considered to be ctenids, such is the majority of the zorid genera. The present study is a preliminary attempt to answer some questions regarding the monophyly of ctenids and their phylogenetic relationships. The results of a cladistic analysis based on a matrix containing 92 morphological characters scored for 58 taxa from about 13 families of lycosoid and non-lycosoid spiders are presented. The analysis includes 26 genera and 38 species of the ctenid subfamilies Acantheinae, Acanthocteninae, Calocteninae, Cteninae, Phoneutriinae, and Viridasiinae. This taxonomic sample attempts to present the diversity of ctenids as well as to test previous hypotheses of ctenid phylogenetic relationships. The implications of these data for the classification of the ctenid spiders are discussed.
Simon, U., Dept. of Animal Ecology and Tropical Biology, University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany.
Is the spider fauna of pine tree crowns predictable?
In temperate ecosystems the occurrence of organisms is said to be determined by abiotical factors. Results from investigations in the tropics indicate that stochasticity is the main factor for the composition of communities of organisms. Therefore, it seems to be necessary to reexamine for temperate systems if there are also stochastical aspects in the composition of communities. Due to its low number of species the spider community of pine tree crowns is an excellent object to study which parts of the community are predictable in the sense of annual occurrence, seasonality and species composition on single trees as well as on the entire collective of investigated trees. There is only a weak connection between the spider community of the previous and the following year. The patterns of seasonality in the spider communities are the same at all three geographical distributed investigation sites. Rank-abundance-patterns show a high variability. Only a third of all species-like taxa of spiders on pine tree crowns occurs in high frequency, and thus, is predictable. The remainder species occur in low frequency as well as in low numbers and are distributed randomly. Conclusively, there seem to exist factors determining but only a part of the spider community in pine trees. In addition, there is also a big part of the community which composition is not predictable. The ecological role of it on the one hand and the biological implications of this phenomenon on the other are still not understood.
Sørensen, L. L., and Scharff, N., Zoologisk Museum, Universitetsparken 15, DK-2100 København, Denmark, and Coddington, J. A., Dept. of Entomology, National Museum of Natural History, NHB-105, Smithsonian Institution, Washington, D.C. 20560 USA
Tropical spider diversity: comparison of canopy and ground faunas.
The existence of species-rich groups combined with an urgent need for conservation have lead to the development of methods for estimating species richness based on quantitative sampling methods. A sampling protocol has been developed to estimate species richness at the ground level. This protocol has been tested, further developed and used in various parts of the world. During a two week period (May-June, 1997) we (and 7 other collectors) sampled for a total of 350 hours, 160 pitfall trap-days, and 1,000 m2 funnels (fogging samples) inside and outside a one hectare plot in a montane forest (1,850m) in Uzungwa Mountains, Tanzania. We complemented traditional sampling methods with canopy fogging using pyrethrum insecticide. Inside the plot we collected 6,315 adults from 177 species, of which 30 (17%) were unique to the canopy. Additional sampling outside the plot added 7,799 specimens from 176 ground species and 46 canopy species, for a grand total of 14,114 specimens of 220 species (thus 43 additional species). The present project aims to determine how diversity, composition, and complementarity of spiders faunas changes vertically (between canopy and forest floor), the effect of plot size on results, and to evaluate further the feasibility of estimating local spider species richness from sample data.
Starr, C. R., Dept. of Life Sciences, University of the West Indies, St Augustine, Trinidad & Tobago, and Daudin, J., Union Island Association for Environmental Protection, Clifton, Union Island, St Vincent & the Grenadines.
What is Argiope argentata doing on Cnidoscolus urens?
The orb-weaving spider Argiope argentata (Araeneidae) and the strongly urticating plant Cnidoscolus urens (Euphorbiaceae) are both very abundant in the Grenadine islands, Lesser Antilles. By way of comparison with another common orb-weaver, Metepeirasp. (Araneidae), it is shown that A. argentata webs are preferentially attached to C. urens. The hypothesis that the spider thus gains protection from vertebrate predators is tested by way of the prediction that stabilimenta will be more frequent and/or larger in webs based on other, non-urticating plants than on C. urens. The proximate basis for this spider-plant association remains unexplored, leaving open the intriguing possibility of chemically-mediated site choice.
SASunderland, K. D., Dept. of Entomological Sciences, Horticulture Research International, Wellesbourne, Warwick, CV35 9EF, U.K.
Effects of spiders on pest populations: mechanisms.
Assemblages of spider species can make significant reductions in pest numbers that are of value to the farmer. A group of spider species with complementary niches leaves few refuges for the pest in space or time. Spiders usually exert an influence on pest numbers in concert with other natural enemies, and spiders are sometimes the dominant component. In addition to killing pests by direct attack, spiders cause pest mortality by dislodging them from plants or trapping them in webs. If the pest is distasteful, or if it is the dominant prey type available, spiders may kill more than they consume, which increases the rate of pest kill per unit of spider food demand. The implications for pest control, of various types of interaction between spiders and other natural enemies, are explored. Interactions with specialist natural enemies usually result in complementary effects, enhancing pest control. Specialists reduce the density of pests to levels where spiders can prevent resurgence. Specialists foraging on the crop may flush pests off the plant to be killed by ground-zone spiders. Although hyperpredation may disrupt biological control occasionally, it is considered that the wide range of competitive interactions between natural enemies, in general, promotes diversity and stability of the natural enemy community and generates a robust basis for pest control.
SASuter, R. B., Dept. of Biology, Vassar College, Poughkeepsie, NY 12604
An aerial lottery: the physics of ballooning in a chaotic atmosphere.
The annual recolonization of many agroecosystems by spiders is accomplished more by aerial deposition of ballooning spiders than by cursorial invasion from refugia such as forests and fence lines. The resulting spider communities can have major direct impacts on prey populations and can therefore strongly influence crop productivity. In this paper I first review what we know about ballooning in the broad sense, and then explore the influence of localized atmospheric structure on the physics and dynamics of ballooning. I used relatively high frequency measurements of air movement (speed and inclination) and insolation, all gathered from a 50-cm2area, to develop a statistical characterization of the aerial microclimate at the top of the canopy in a field dominated by goldenrod (Solidagosp.). I then analyzed the known physics of ballooning in the context of that statistical characterization. The major findings are (1) that local conditions conducive to ballooning by all but the smallest spiders are rare and unpredictable, (2) that the spider's perception of the current state of its microclimate, at least with respect to air direction and speed, has almost no predictive value and can only contribute to the spider's decision-making in a statistical sense, and (3) that the size distribution of the population of aeronauts is well explained by constraints imposed by aerodynamics and the probabilistic structure of the turbulent atmosphere.
SAThomas, C. F. G. andJepson, P. C., Dept. of Biology, University of Southampton, Bassett Crescent East, Southampton SO9 3TU, UK
Differential aerial dispersal of linyphiid spiders from grass and cereal fields.
Ground and aerial populations of linyphiid spiders were sampled in and above differently managed grass and cereal fields, monthly from May - September 1990, and weekly from June - August 1991. Data were used to calculate indices of aerial activity reflecting changes in the propensity of the spiders to disperse by ballooning. Aerial dispersal occurred at high frequency, with higher aerial activity indices, indicating higher dispersal rates, for adults in July and immatures in August. Aerial activity indices were generally higher in samples from the senescing cereal field. Aerial activity indices were higher for males than females and the dispersal peak occurred earlier. In 1991 immatures dispersed from the cereal field in July and August and from the grass field mainly in August. Differences in aerial activity are discussed with reference to dispersal strategies that might operate to maximize spider survival in the patchy, disturbed agricultural landscape.
SAToft, S., Dept. of Zoology, University of Aarhus, Bldg. 135, DK-8000 Århus C, Denmark
Prey choice and spider fitness.
Though spiders in general are polyphagous, indiscriminate feeding is not advantageous, because insects vary enormously in quality due to toxicity or nutrient deficiency. Active prey selection serves to find the optimal compromise between three "nutritional goals": maximize energy intake, balance nutrients and minimize toxin consumption. Consumption of toxic prey is reduced by more or less specific acquired aversions, probably associated with both prey taste and behavior. Spiders' ability to avoid toxic prey seems limited because aversions are short-lasting and some toxic prey do not induce an aversion; such prey may be lethal. Toxic prey in a mixed diet may inhibit feeding on and utilization of good prey. Induced tolerance to toxic prey may be possible, however. Nutritional balance may be obtained through consumption of high-quality prey or through mixing of good prey types. It is argued that nutrient balance is more important for fitness than maximization of energy intake.
SATopping, C. J., Dept. of Landscape Ecology, NERI, Kalo, Grenåvej 14, DK-8410 Ronde, Denmark
An individual-based model for dispersive spiders in agroecosystems, with some simulations of the effects of landscape structure.
A general individual-based model of spiders in agricultural land was constructed. The populations of spiders were simulated on landscapes which were defined from a set of landscape descriptors based on a Danish agricultural landscape. These descriptors gave the types of habitats present in the landscape together with their area and a frequency distribution of the size of individual habitat patches. The agricultural land was divided into crop types each with their own array of crop management, which were considered to influence the spiders via mortality. The dimensions of the model are relatively large with the spider population able to grow up to a size of one million individuals and with a spatial resolution of 108 landscape units. The effect of altering the spatial organization of the landscape elements was investigated together with the influence of the size of fields in the agricultural landscape. Results showed that the spatial arrangement of landscape elements did not affect spider population, but that the effect of increasing habitat patch size, whilst maintaining a constant habitat area, was to increase population sizes with a preferential increase in population sizes for simulations where dispersal was minimal. Simulation results indicated that the optimal dispersal strategy for spiders in this system was one of high juvenile dispersal, although the extent to which these results can be translated to other systems is not yet known. These results indicate the potential for using models of this type for theoretical investigations of the life-history strategies used by spiders.
Toth, Ferenc and Kiss, Jozsef, Goedoelli University of Agricultural Sciences, Dept. of Plant Protection H-2103 Goedoelli, Pater K. u. 1. Hungary
Comparative analysis of the spider fauna of winter wheat fields and adjacent field margins.
In order to study the three most important taxa of the epigeic predatory arthropod fauna of winter wheat (Carabidae, Staphylinidae, Araneae) the Department of Plant Protection of the Goedoelli University of Agricultural Sciences, carried out pitfall trapping in winter wheat fields and adjacent margins in the area of Kartal and Jozsefmajor (northern Hungary) during three consecutive years, 1992, 1993 and 1994. Research aims: (1) examination of the epigeic spider assemblages of winter wheat fields and adjacent margins, (2) study of dominance structures, (3) study of the seasonal dynamics of dominant species, (4) comparative analysis of the spider fauna of the field and adjacent margins, (5) establishment of future Hungarian studies to determine the role of spiders in the protection of winter wheat. Results: a total of 9613 individuals were identified from pitfall traps which consisted of 149 species from 19 families. From the winter wheat, 118 species were collected and similarly (with fewer traps) 118 species were collected from the margin. There were 87 species which occurred in both habitats. Seven species were identified that have previously not been recorded in Hungary. This work has demonstrated that in the case of the surveyed northern Hungarian winter wheat fields, margins are more diverse habitats with respect to the spider fauna. Margins may be an important, though not exclusive source of spiders, enabling them to immigrate into the fields. Furthermore, margins provide habitats for many rare species that are unable to survive within the fields.
Tuntibunpakul, P., and Wise, D. H., Dept. of Entomology, University of Kentucky, Lexington, KY 40546-0091
The impact of spiders and carabid beetles on the abundance of insect pests and yields in vegetable gardens.
The extent to which spiders and carabid beetles limit pest populations in vegetable gardens and enhance vegetable production was evaluated in two different field experiments. We established gardens with different densities of spiders and carabids by employing different combinations of mulch addition; fencing; removal of spiders and carabids by trapping and hand-collecting; and predator addition. In 1996 we compared responses in open control and fenced-predator removal plots. In the 1997 experiment, fenced predator-removal and fenced predator-addition treatments were compared. In 1996, spider and carabid predation in mulched mixed-vegetable gardens marginally depressed densities of squash bugs in cucumbers (p=0.09), and significantly lowered Colorado potato beetles (CPB) in potatoes (p=0.04). In plots with more spiders and carabids, total weight of cucumbers harvested was marginally higher by c. 60% (p=0.10); in addition, marketable cucumbers were c. 20% heavier (p=0.002). The yield of Pontiac potatoes was not affected, but Kennebac potato yields were c. 50% greater (p=0.06) in plots with higher densities of spiders and carabids. The 1997 experiment focused entirely on Kennebac potatoes. Unlike the previous year, in 1997 higher numbers of spiders and carabid beetles did not reduce CPB numbers and had no impact on Kennebac potato production. Our results suggest that predation by spiders and carabids has the potential to limit vegetable pests and increase vegetable yields, but further experiments are needed to determine the year-to-year consistency, and the magnitude, of such effects.
SAUetz, G. W., Dept. of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221-0006, Halaj, J. and Cady, A. B., Dept. of Zoology, Miami University, Oxford, OH 45056
Guild structure of spiders of major crops.
The ecological guild concept has been of great interest to arachnologists, and the different manner in which spiders forage for a common resource - prey arthropods - has led to numerous attempts to classify them into guilds. However, questions have been raised about the validity of guilds and the taxon-centered basis of their definition. Here, we propose an alternative approach to guild classification, using quantitative analysis of ecological characteristics of spider families. While generalizations may not apply to all species within a taxon, results from this approach do support earlier guild assignments by some authors, and provide a reasonable framework for future studies. We used this classification in a comparison of spider guild composition across several major crops (from published studies). While total species richness varied widely among crops, the proportion of the total species within each guild was remarkably even across crops. The relative abundance of guilds (based on numbers of individuals) varied greatly, which may reflect availability of resources within a crop type. Patterns of similarity in guild composition suggest the possibility of plant habitat structure as an influence on the spider community. As recent studies have shown that assemblages of spiders can impact pest populations and reduce crop damage, a better understanding of spider guild composition and variation in spider community structure among crops is essential in future studies of the arthropod fauna in agroecosystems.
Uetz, G. W., Persons M., Delaney, M. K., Smith, E., Orr, M., Pruden, A. J., Mendoza, R. and Kilinc, B., Dept. of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221-0006
Male decorations, courtship vigor and mate choice in wolf spiders.
Male Schizocosa ocreata(Hentz) exhibit multiple traits that may serve as condition indicators used by females as criteria for mate choice. In this study we examine the influences of static (foreleg tufts) and dynamic (behavioral) traits with mating experiments and video playback studies. Male S. ocreata collected in the field or raised in the lab under various feeding regimes were paired with females, and courtship behavior was recorded and analyzed. We also measured responses of females to video images: 1) the same courting male with increased or decreased display rate (speed of leg-waving) and inter-bout interval; 2) video males with controlled courtship vigor but modified tuft size. Traits varied significantly among males; males that mated with females had larger tufts and increased courtship vigor. Male courtship vigor and tuft size varied significantly with feeding history; well-fed spiders had larger tufts, had more frequent courtship bouts, and shorter interbout intervals than deprived spiders. Video studies suggest that female spiders' receptivity varies in response to manipulation of each of these traits independently; females showed significant differences in receptivity between control videos and altered video images with increased/decreased rates of display or inter-bout intervals, as well as modified tuft size. Multiple male traits may influence mate choice, but females may choose males on the basis of variation in a single trait. Relationship(s) between indicator traits and male body condition suggest that static traits (e.g., tuft size) may be more reliable indicators than dynamic traits (e.g., courtship vigor).
Valderrama, C., Ecology, Evolution and Organismal Biology Dept. 310 Dinwiddie Hall, Tulane University, New Orleans, LA 70118
Vertical distribution of orb weaving spiders in a Colombian cloud forest.
In order to determine the effect of changes in habitat structure due to natural and anthropic disturbances on biodiversity, I evaluate the role of availability of supports for webs and the spatial distribution of insects on the vertical distribution of orb weaving spiders. I quantified the vertical distribution of spiders and preys in a Colombian cloud forest (Reserva Natural La Planada, Nario. 1850 m. elev.). The three habitats were: closed-canopy primary forest, secondary forest (regenerating cattle pastures that had been abandoned more than ten years before), and natural clearings (formed by recent tree falls within the primary forest). The distribution of spiders was compared by direct observation. The vertical distribution of flying insects (putative prey) was compared in the three habitats with sticky traps. A total of 1,188 adult spiders were observed, representing 46 species and 8 families. The highest species richness was in the primary forest, followed by secondary forest and clearings. The largest number of insects captures were registered in the secondary forest, followed by the natural clearings. The availability of support structures for webs, particularly epiphytes, appears to play an important role in the vertical distribution of orb-weaving spiders in cloud forests. The greater abundance of insects in the lowest strata of the forest coincided with the greater abundance of orb-weaving spiders. However, in primary forests a second peak of insect abundance occurred in the canopy.
van der Merwe, Marius, Field Museum, Dept. of Zoology, Division of Insects, Roosevelt Rd. at Lake Shore Dr., Chicago, IL 60605, United States, Dippenaar-Schoeman, A. S.,Plant Protection Research Institute, P/Bag X134, Pretoria, 0001, South Africa, and Scholtz, C. H., Dept. of Zoology and Entomology, University of Pretoria, Pretoria, 0002, South Africa
A survey of ground-living spiders in indigenous forest and pine.
A survey of ground-living spiders was conducted over one year at Ngome State Forest, South Africa. Five different habitat types: grass, open forest, dense forest, mixed pine, and pine were sampled with 180 pitfall traps. The grass, open forest and dense forest represented indigenous vegetation while the pine represented exotic (and unnatural) vegetation. The "mixed pine" consisted of a mixture of invading indigenous forest plants and pine trees. Multivariate analysis of the data showed different habitat types to support different ground-living spider communities. Rank-abundance curves for all habitats approximated those of the truncated lognormal model. An ANOVA of Shannon's diversity index failed to distinguish significant differences in species diversity between habitat types. Smaller web-building spiders (especially Linyphiidae) seem to dominate in pine, and generally larger, wandering spiders seem to be more typical of indigenous vegetation. The results support the notion that the planting of pine trees largely affects the composition of ground-living spider communities, but not diversity.
Vetter, R. S., Dept. of Entomology, University of California - Riverside, Riverside, CA 92521
Envenomation by a grass spider, Agelenopsis aperta (Agelenidae).
This is the first report of clinically significant bites by the grass spider (Agelenopsis aperta). Two cases of envenomation in southern California are presented. In the more serious case, the victim, a child, exhibited several envenomation symptoms, some of which are similar to that of the bite of the confamilial hobo spider, Tegenaria agrestis, found in the Pacific Northwest in the U.S. Although A. aperta may turn out to be generally innocuous, it should be considered as a creature of occasional medical importance. Many skin lesions are attributed to spider bites despite insufficient incriminating evidence and bites which are clinically significant may often erroneously be attributed to the brown recluse (as it was in the case here with the child). Misidentification can lead to undue anxiety in a victim's family.
Vink, C. J., Soil, Plant & Ecological Sciences Division, Ecology & Entomology Group, PO Box 84, Lincoln University, New Zealand
Past, present, future: the taxonomy and systematics of the New Zealand Lycosidae (wolf spiders).
The taxonomy and systematics of all New Zealand Lycosidae is being investigated. A preliminary taxonomic and phylogenetic study of a putative group of eight species (the "hilaris group") and two outgroup species has been done. Lycosids in the "hilarisgroup" are often numerically dominant ground-dwelling predators in agroecosystems in New Zealand. The "hilaris group" species (four new and four redescribed) are placed in a new genus. A second new genus is described (with a redescription of the species). The genus Allotrochosina is redefined and A. schauinslandi is redescribed. Distributions of all 10 species are mapped. A phylogeny for all 10 species that indicates strong support for monophyly of the new genus containing the "hilaris group" is derived using parsimony analysis of morphological characters.
Walker, S. E.,Balfour, R. A., Marshall, S. D. and Rypstra, A. L., Dept. of Zoology, Miami University, Oxford OH 45056
Differences between males and females: functional response and partial prey consumption in two species of wolf spider (Araneae: Lycosidae).
A dichotomy exists between male and female spiders in both morphological and behavioral characteristics. We examined how males and females allocate time and energy to feeding by documenting the functional response of both sexes in two species of wolf spider, Pardosa milvina and Hogna helluo. Both species exhibit a Holling type 11 functional response in which the number of prey killed approaches an asymptote hyperbolically as prey density increases. Males of both species do not consume or kill as many prey as do females. In both species, the rate of partial prey consumption increases with prey density and in some cases this may represent wasteful killing. Partial prey consumption is much more obvious in female H. helluo than in male H. helluo or either sex in P. milvina. The differences between males and females in this study are correlated with differences between species in body size. These data provide further evidence that female spiders are energy maximizers and male spiders are time minimizers.
PLWeygoldt, P., Albert-Ludwigs-Universitat, Institut für Biologie I (Zoologie), Hauptstrasse 1, D-79104 Freiburg, Germany
Spermatophores and the evolution of female genitalia in whip spiders (Chelicerata, Amblypygi).
Whip spiders use stalked spermatophores for sperm transfer. Usually, paired sperm masses hidden within the spermatophores are small, and there has been a co-evolution of spermatophores and those parts of the female genitalia which are used to pick up and to store the spermatozoa. These are specialized sclerotizations, glands or, in a few species, seminal receptacles which are hidden inside the genital atrium (or uterus externis). In most species there are paired erectile bodies, homologous to genital appendages, which are attached to the dorsal side of the genital operculum. The comparison of spermatophores and genitalia of different species belonging to most genera and families suggest that the female gonopods primarily consist of paired cushion-like structures, each equipped with a small finger-like appendage vestige. These appendage vestiges are retained in many species, in particular in the Charinidae and Charontidae. They are erectile by increase in blood pressure, and are thereby probably bent in characteristic ways and thus can pull off the sperm masses from the spermatophore. In some species these appendage vestiges are totally lost. In the Phrynidae, on the other hand, they have become sclerotized and hard. They form the well-known claw-like sclerites, and an invagination at the base of each sclerite has been shaped to form a true seminal receptacle. Similar genitalia have evolved convergently in the genus Trichodamon(Phrynida, Phrynichidae). Spermatophores and the corresponding female genitalia and their mechanisms of a number of genera from most families are demonstrated.
Wise, D. H. and Chen, B., Dept. of Entomology, University of Kentucky, Lexington, KY 40546-0091
The community ecology of woodland Schizocosa: trophic interactions of a forest-floor wolf spider.
We investigated the trophic connections of woodland Schizocosa in order to understand the ecological interactions of a common wolf spider, and also to begin uncovering patterns of bottom-up, top-down and lateral control processes in the detritus-based food web of deciduous leaf litter. We performed four separate field experiments: (1) Adding high-quality detritus to open plots for 3.5 months increased the biomass-density of juvenile Schizocosa c. 5x over control values. (2) Excluding vertebrate predators from fenced and netted areas for 15 months did not increase densities of juvenile or adult Schizocosa compared to open reference areas. (3) Reducing densities of centipedes and other spiders did not improve survival of recently hatched Schizocosa, even though mortality rates were high. In contrast, reducing arthropod predators enhanced the survival of older juvenile Schizocosa by > 50% in 2 of 3 locations. Survival of the older Schizocosa was negatively correlated (r = -0.76, P < 0.001) with densities of gnaphosids and ctenids, which readily ate Schizocosain laboratory trials. (4) Reducing densities of Schizocosa and other non-web spiders by periodic live-trapping for 1.3 years in fenced plots caused a 2x increase in densities of large, active species of Collembola (Tomocerinae). These experiments reveal substantial bottom-up limitation of juvenile Schizocosa. Evidence of top-down control of tomocerid Collembola by Schizocosa and other cursorial spiders is clear. Patterns of top-down limitation of Schizocosa densities by its natural enemies are more complex, due to spatial heterogeneity, trophic-level omnivory, and compensatory effects of intraguild predation and cannibalism.
SAWise, D. H., Snyder, W. E., Tuntibunpakul, P., Dept. of Entomology, University of Kentucky, Lexington, KY 40546 and Halaj J., Dept. of Zoology, Miami University, Oxford, OH 45056
Spiders in decomposition food webs of agroecosystems.
The involvement of spiders in decomposition food webs has the potential to affect agricultural productivity through two quite different types of interactions: (1) cascading, top-down effects of spider predation on rates of nutrient mineralization; and (2) a linkage, through spiders, between decomposition and grazing food webs (energy from the detrital web contributing to elevated spider densities, which in turn might reduce pests and enhance net primary production). Scant experimental evidence exists to refute or support either hypothesis. The first set of interactions is most likely to be of significance in no-till and conservation tillage farming. In theory, spiders have the potential to enhance productivity by increasing rates of mineralization, but theory also predicts that spiders, by preying on important detritivores and fungivores, depress rates of litter decomposition. Field experiments by Kajak and her colleagues have uncovered such negative effects of spiders in mown pastures. This negative effect could reduce plant growth, but the expected time lags in most types of crops suggest that the overall impact of spiders on plant production will be determined more by the interactions comprising the second hypothesis. However, the hypothesis that bottom-up control processes in the decomposition web affect crop productivity via energy subsidies to spiders and other generalist predators in the grazing web remains conjecture without clear experimental confirmation. This hypothesis should be tested in agroecosystems in which detritus-based food webs can feasibly be manipulated.
Yan, Hengmei and Wang, Hongquan, Dept. of Biology, Hunan Normal University, Changsha, 410081, PRC China, Supported by the National Natural Science Foundation of China
Contribution of biocontrolling insect pests by spiders to improve the rice-based ecosystem.
Based on our investigations made in recent years, 373 species, 109 genera and 23 families of spider have been identified, constituted 51.2%-89.5% of predacious natural enemies in rice fields of China. Among them, 17 species are dominant: Tetragnatha maxillosa,T. caudicula, T. javana, Dyschiriognatha quadrimaculata, D. yiliensis, Ummeliata insecticeps, Hylyphantes graminicola, Gnathonarium gibberum, G. dentatum, Paradosa pseudoannulata, Pirata subpiraticus, P. piratoides, P. piraticus, Clubiona japonicola, C. corrugata, Coleosoma octomaculatum and Oxyopes sertatus. The higher peak of spider population appeared respectively in July with 450,000 individuals/hectare and September with 900,000 individuals/hectare, upwards to 1,500,000-3,000,000 individuals/hectare after conservation in the field. The results indicate that spiders have a good appetite for living insects. They can live and work in the field for a long time, and become a balanced force in controlling the pests. The changes in the population number, habits and metamorphosis of the life history of both planthoppers and dominant spiders are similar. Through conservation of spiders, the size of populations of many predators, such as spiders, green lacewings, lady beetles and so on, are increased. Moreover, the populations are larger than that of fields, which are controlled by chemical methods. That various kinds of natural enemies unite against the pests is fully displayed. As a result, the area needed for chemical control has becoming smaller in the field with pollution decreased in the agro-ecosystem. It is obvious that spiders play an important role in controlling the pests in fields and improve the rice-based ecosystems.
Yañez, Martha, Cruz Del Norte No. 7, Sta. Cruz del Monte, Edo. de Mexico, CP. 53110, Mexico, Locht, Arturo, Belisario Dominguez No. 123, Coyoacan, CP. 04000, Mexico, and Macias-Ordoñez, Rogelio, Instituto de Ecología, A.C., Apartado Postal 63, Xalapa, Veracruz 91000, Mexico
Courtship and mating behaviour of Brachypelma klaasi Schmidt & Krause 1994 (Araneae:Theraphosidae).
Courtship and mating behaviour of Brachypelma klaasi, heretofore unknown, is described on the basis of three courtship and mating sequences, one in captivity and two in the field. Adult males perform courtship movements (pedipalp drumming, leg drumming, push-up, and shaking) when they locate females burrows, probably in order to avoid female aggression. After some physical contact, the female raises the prosoma and extrudes her chelicerae. The male then grasps her chelicerae with his claspers and the female arches the body backwards leaving the epigynum exposed. The male starts boxing the female's sternum and presumably inserts his pedipalps and inseminates the female. In two cases the female viciously attacked the male after mating and probably would have killed him had the observers not intervened; the other pair separated more slowly and peacefully.
Yin, Changmin andPeng, Xianjin, Dept. of Biology, Hunan Normal University, Changsha, Hunan Province, P.R.China 410081
Study on the Chinese spiders of the family Gnaphosidae (Arachnida: Araneae).
In our recent 3 papers, we described 4 genera of family Gnaphosidae including 2 new genera, 9 new species, 1 male supplement of Gnaphosa dege and a discussion about the identification of female Zelotes liaoi. There are 2 new genera and 9 new species. Diagnoses, descriptions, illustrations and the locality of above species are reported. A new genus is similar to Zelotes by having a preening comb on metatarsi III & IV, but can be separated by lacking the intercalary sclerite of the male palp organ. Its genital structures also differ from those of any other genera of zelotines, such as: distal end of embolus bends to form a bow-like structure. Embolus base is a semicircular ring-like sclerite. The epigynum has a large atrium and a pair of round copulatory sacs. Another new genus can be separated from all other gnaphosids by having an unique long and coiled embolus, lacking the preening comb on metatarsi III & IV and without any keel or lamina on retromargin of the chelicera. Type specimens are deposited in Department of Biology, Hunan Normal University, Changsha, Hunan, China.
Ysnel, F. and Canard, A., Laboratoire de Zoologie et d'Ecophysiologie, UMR CNRS 6553, Université de Rennes I, Campus de Beaulieu, 35042 Rennes Cedex, France
Spider biodiversity in connection with an ecological classification of hedges based on the vegetation structure.
The relationship, between an index of hedge ecological quality based on the analysis of the vegetation architecture (vegetation diversity, foliage cover) of hedges and the structure of the spider communities associated was investigated. The comparison deals with 6 hedges of low, median and high ecological value. The data suggest that the specific richness and the specific composition of dominant spiders always remain the same for the different group of hedges. It is supposed that as well as the structure of the vegetation, the foliage orientation of the hedges may induce substitution of species. Indicating species of the differences between ecological quality of two hedges could be required among the groups of species absent from one hedge.
Zingerle, V., Institute of Zoology and Limnology, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
Spider communities along a glaciation transect in the Italian Dolomites.
Spider communities of alpine grassland, of screes and woodlands near the timberline and of the nival zone have been compared along a transect from the northern to the southern border of the Dolomites. The region is zoogeographically interesting because of differences of the ice cover during glaciation, which was less severe in the southern area. Along the whole transect spider communities in grasslands and at the timberline zone show approximately the same composition. Endemic species, e.g. Harpactea grisea (Canestrini 1868), Amaurobius ruffoi Thaler 1990, Coelotes mediocris Kulczynski 1887, Cybaeus intermedius Maurer 1992 and Eudasylobus ligusticus Roewer 1923, occur mostly on the southernmost station, which remained free of ice. Re-immigrants over short distance are scarce, e.g. Coelotes mediocrisat Passo Rolle and Coelotes solitarius L. Koch 1868 in Puez area. Endemic species were not found in the alpine grassland of the northern Dolomites, which suggests severe impact of glacial events on the local fauna. Central alpine species, i.e. Erigonella subelevata (L. Koch 1869), Metopobactrus nadigi Thaler 1976, Meioneta orites (Thorell 1875), Pardosa blanda (C.L. Koch 1833) and Pardosa mixta (Kulczynski 1887), are still present at the southernmost boundary of the Alps. Nunataks in the northern and central area of the Dolomites allowed speciation effects within the nival fauna: Lepthyphantes brunneri Thaler 1984, Lepthyphantes merretti Millidge 1974, Megabunus armatus (Kulczynski 1887). Further zoogeographically interesting records are Cryphoeca nivalis Schenkel 1919 and Xysticus bonneti Denis 1938.
Zujko-Miller, J., Dept. of Biological Sciences, The George Washington University, Washington D.C., 20052, USA, and Dept. of Entomology, National Museum of Natural History, NHB-105, Smithsonian Institution, Washington D.C., 20560, USA
A cladistic revision of Sisicottus(Araneae, Linyphiidae, Erigoninae): systematics without monotypic genera.
I have completed the first revision of the erigonine spider genus Sisicottus Bishop & Crosby 1938. A cladistic analysis was performed to reconstruct phylogenetic relationships within Sisicottus. All nine Sisicottus species, including five new species, and seven outgroup species were coded for 40 phylogenetically informative characters. The monophyly of Sisicottus is unambiguously supported by eight putative synapomorphies. Two species were transferred out of Sisicottus. Typhochrestus uintanus (Chamberlin & Ivie 1939) was described in Sisicottusapparently based on a misinterpretation of homology. Carorita hiberna (Barrows 1945) was inexplicably described in Sisicottus and shares none of the synapomorphies of Sisicottus. Cladistic analysis of C. hiberna and six other erigonine taxa coded for 22 phylogenetically informative characters placed C. hiberna elsewhere.
Ainsworth, C., Slotow, R., Biology Dept., University of Natal, Private Bag X10, Dalbridge, Durban 4041, South Africa, Crouch, T., Durban Natural Science Museum, P.O. Box 4085, Durban 4000, South Africa and Lubin, Y., Mitrani Centre for Desert Ecology, Blaustein Institute for Desert Research, Ben Gurion University, Sede Boqer, 84990 Israel
A test for behavioral tasking in prey capture by social spiders Stegodyphus mimosarum(Araneae: Eresidae).
Stegodyphus mimosarum are social spiders that inhabit dry, African savannah. They form communal nests of up to several hundred individuals, and co-operate in nest construction and maintenance, brood care and prey capture. To date, there has been no conclusive evidence of tasking in these or other social spiders. If tasking occurs, small spiders should approach and attempt to subdue less dangerous prey items such as flies more often than the more dangerous prey items such as bees. Hunger and poison availability were also expected to play a role in any such strategies. Functional spider nests were removed from Weenen and Itala Game Reserves. The spiders were separated out into smaller colonies and individually marked. A series of behavioral observations were then made and recorded regarding tasking in prey capture and the effect of poison availability and hunger on this activity. Hungry individuals were significantly more willing to accept the costs associated with prey capture than the satiated spiders i.e.: to venture out of the nest refuge. These spiders have poison glands that presumably become depleted during prey capture. Apparent depletion of poison in previous prey captures did not significantly affect an individual's response to a prey item. The results showed no evidence of tasking in these spiders. The variable tested showed no significant differences between the behavior of the large and small spiders based on the size of the spider. Prey type was more important in determining the response of both large and small spiders that reacted similarly to the different prey types. The two-way interactions between spider size and prey type were never significant suggesting no relationship exists between the size of the spider and its behavior.
Alayon, Giraldo, Museo Nacional de Historia Natural, Apartado Postal No. 20, San Antonio de los Banos, C.P. 32500 La Habana, Cuba
Biodiversity of Cuban spiders: an analysis.
This study of Cuban spiders considered three groups: 1. European 2. North American and 3. national.The spider family Theraphosidae has more percent of endemic species than the rest of the 52 other families that are registered in the archipelago. The Cuban institutions contain more than 30,000 specimens in 8 different collections. Most of the types of Cuban spiders are deposited in museums in the United States.
Amalin, D. M. and Pena,J. E. , TREC-IFAS, University of Florida, 18905 SW 280 St., Homestead, FL 33031
Selective toxicity of some pesticides to Hibana velox, a predator of citrus leafminer.
Toxicity effect of 14 pesticides on Hibana velox was determined under laboratory conditions using contact exposure bioassay test. Two methods were tried, such as dipping method for 5 insecticides and surface coating method for 9 pesticides. Three concentrations were prepared for each pesticide, namely simulated field rate (SFR), twice of SFR, and half of SFR. A control treatment was also included for each test. The five insecticides tested using dipping method were Abamectin plus Oil, Dimilin, Bacillus thuringiensis, Azadiractin, and Oil alone. All of these insecticides exhibited low toxicity even at the highest concentration (twice of SFR). The toxicity level of the 9 pesticides tested using surface coating method differed significantly from each other. Imidacloprid-Admire and copper showed low or no impact on H. velox. Abamectin and Imidacloprid-Provado had moderate effect. Whereas, ethion, Azinphos-methyl, dicofol, chlorpyrifos, and carbaryl exhibited high toxicity. The results of these toxicity tests suggest that extreme caution must be undertaken for pesticides showing high toxicity before applying in the field. The population of the predatory arthropods must be checked first before spraying.
Andrade, R. and Gnaspini, P., Departamento de Zoologia, Instituto de Biociencias, Universidade de São Paulo, Cx.P. 11461, 05422-970 São Paulo, Brazil
Study of the life history of the cave pseudoscorpion Maxchernes sp. (Chernetidae) in the laboratory.
Aspects of the life history of the cave pseudoscorpion Maxchernes sp., such as feeding, reproduction, and postembryonic development, have been observed in the laboratory. The pseudoscorpions have been collected in frugivorous bat guano piles from Alambari de Baixo Cave (Ribeira River valley - Sao Paulo, Brazil). In the laboratory, they were kept in small Petri dishes (2cm diameter) with moistened guano under almost constant conditions of darkness and temperature. Drosophilaadults were offered as food. The adults fed approximately once in a month. This frequency increased for females in reproductive season. The mating, with a previous dance, spermatophore deposition, and resting period, was observed. Its span oscillated between 50 and 100 minutes. Hatching occurred inside brooding nests built by females. The postembryonic development and respective molts were observed in laboratory. The duration of each instar showed a large variation, probably related to quantity and/or quality of food ingested. The protonymph lasted 54.0 ± 16.7 days, the deutonymph lasted 23.3 ± 9.5 days, and the only tritonymph observed lasted 42 days. The minimum time spent by the adult phase was 14 months under laboratory conditions.
Anton, T. G., Division of Amphibians and Reptiles, Field Museum, Roosevelt Road at Lakeshore Drive, Chicago, IL 60605, and Redmer, M., Division of Natural Heritage, Illinois Department of Natural Resources, 30071 S. Rt. 53, Wilmington, IL 60481
Current distribution and status of the common striped scorpion Centruroides vittatus in Illinois.
There have been few if any studies on the conservation biology of North American scorpions. The common striped scorpion Centruroides vittatus is a widely distributed North American species, and the only native scorpion known in Illinois. Museum specimens from Cook and McHenry counties (northeastern Illinois) represent introductions by humans. Those from Monroe and Randolph counties (southwestern Illinois) from 1948-1982 represent populations which arrived in Illinois naturally. Surveys were conducted from May to June 1996 at historic localities in Monroe and Randolph counties in the floodplain of the Mississippi River. Although documented from only one county (Monroe), C. vittatus was abundant (5 individuals found per 10-15 min. visit at 9 of 10 localities surveyed). All C. vittatus were found under cover during daylight hours, almost entirely on rock (limestone, sandstone talus) substrate. Of 53 individuals found, 47 (88%) were adults, and 6 (11%) were of the 5th instar or smaller. Six males and 47 females yielded a sex ratio of 8:1 (X 2=31.7, p=0.01). No conservation measures were recommended, although the restricted range of C. vittatus in Illinois (ca. 9.6 km2 in one county) suggest further research on the species is needed and habitat management warranted. Suburban development in Monroe County is increasing, and continuation of such development could eventually threaten C. vittatushabitat.
Baptista, R. L. C., Dept. of Entomology, National Museum of Natural History, Smithsonian Institution, Washington-DC 20560
A new group of Pholcusfrom eastern United States (Araneae: Pholcidae).
To date, no endemic members of the family Pholcidae have been described from eastern USA. The finding of 4 undescribed species of Pholcus from southeastern USA (and one additional species from Bahamas) is striking, as these spiders are large pholcids, with conspicuous webs. The species have been collected in Alabama, North Carolina, Virginia and the District of Columbia. The District of Columbia locality is doubtful, as only one specimen from the Marx collection is known. All 5 species belong to a monophyletic group, defined by the apomorphic morphology of male genitalia, especially the three-pointed appendix. No close relatives to this group could be found so far, even after the examination of almost all the descriptions of Pholcus species and also of a large amount of specimens from all the world. The only other species of Pholcus known to occur in eastern USA are Pholcus phalangioides Fuesslin and P. manueliGertsch. Both species belong to completely different species-groups. All the citations of P. opilionoides Schrank from eastern USA examined to date are misidentifications of P. manueli. All the undescribed species are known only from a few specimens. Any information about Pholcus from USA would be greatly appreciated.
Baptista, R. L. C., Galanis, G., Coddington, J., Suman, T. and Larcher, S., Dept. of Entomology, National Museum of Natural History, Smithsonian Institution, Washington-DC 20560
Spiders of the Chesapeake Bay Region.
The Chesapeake Bay area is one of the most important ecosystems in the eastern USA. Our goal is to make an inventory of spiders of the area (defined as to include all the neighboring counties to the bay and the tidal part of its tributaries, encompassing most of Maryland, eastern Virginia and the entire state of Delaware). Besides searching all relevant collections and going through all papers known to cite specimens for the area, we plan to apply the inventory techniques developed by Coddington and collaborators in three different sites along the bay. The criteria for choosing the sites are: high habitat diversity and minimum anthropogenic impact. The chosen areas are Calvert Cliffs State Park and neighboring area (Calvert Co., MD), Elk Neck State Park and neighboring area (Cecil Co., MD) and Cumberland Marsh (New Kent, VA). Several collecting trips to Calvert Cliffs and other localities in Chesapeake Bay area have been done. The compilation and updating of the citations is near completion and the collection of the NMNH, Smithsonian Institution is being searched for additional records. To date, a list of 412 species from Chesapeake Bay area, including 6 new records for Maryland, has been compiled, referring to the examination of over 2500 specimens and all literature citations.
Barnes, J. D., Dept. of Biology, Vanderbilt University, Nashville, TN 37235, and Polis, G. A., Dept. of Biology, Nashville, TN 37235
Increased abundance and biomass of web spiders at a lake shore: subsidies by aquatic insect imagoes.
Orb web spiders were surveyed at pier structures at the shore and inland at Elm Hill Marina, Percy Priest Lake, Nashville, TN in 1995 and 1996. Censuses of spider abundance, biomass, and web dimensions were conducted along with prey collection. Results indicate significantly higher (5.3 times more) spider number per unit pier area on shore vs. inland piers. Biomass is also significantly higher at the shore. Prey surveys indicate that the vast majority of prey items in orb webs are imagoes of aquatic insects. This study further illustrates the importance of allochthonous subsidies of resources to consumer populations.
Barrion, A. T., Entomology and Plant Pathology Division, International Rice Research Institute, P.O. Box 933 1099, Manila, Philippines, and Proszynski, J., Zaklad Zoologii WSRP, ul. Prusa 12, 08-100 SiedIce, Poland
Revision of the antlike spider genus Myrmerachne in the Philippines with notes on prey composition of four species.
The antlike spider genus Myrmerachnein the Philippines is revised. A total of 20 species are redescribed, figured and keyed for identification. The spider genus Emertonius Peckham and Peckham is reconsidered. Two species have been transferred to other genera. One species is synonymized. M. plataleoides O.P.-Cambridge is newly recorded from the Philippines. Distributional data for all species are provided and the prey composition for M. assimilis, M. bakeri Banks, M. pinakapalea Barrion and Litsinger and M. plataleoides are documented.
Beals, M. L., Dept. of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996
Niche breadth measurement in spiders: A comparison based on indices of species co-occurrence and habitat associations.
Two measures of species niche breadth (correlation of species with habitat variables and patterns of species co-occurrence) were applied to describe the structure of three spider communities in East Tennessee. An old field, a tussock-grass field, and a deciduous woodland (dominated by Liriodendron tulipifera L.) were censused using circular quadrat sampling in the summer of 1997 as part of a two year study. In each quadrat the following data were recorded: spider species present; plant species present and percent cover; and vegetation architecture, density, and maximum height. In the deciduous woodland, depth and taxonomic composition of the litter were also recorded. Species associations with habitat variables and with other spider species were examined. These data are used to generate estimates of niche breadth for each species. Preliminary analyses indicate that individual spider species are primarily correlated with other spider species, while families generally show significant correlation with plant species.
Beck, J. B. and Toft, S., University of Aarhus, Dept. of Zoology, Building 135, Universitetsparken, DK-8000 Århus C, Denmark
Genetic variation for tolerance to consumption of aphids in Lepthyphantes tenuis.
Aphids are low-quality food for spiders and other generalist predators in cereal fields. Though they may contribute to a higher reproductive output in mixed diets, it is possible for the spiders to consume only a limited amount of them. On a pure aphid diet reproduction is reduced and no spiderling will reach maturity when fed only aphids. In a biological control perspective it would be interesting to know if there is variation in the tolerance to aphids and especially to what extent this is genetic. To examine if hereditary variation exists a breeding program was carried out. Hatchlings of field collected Lepthyphantes tenuis(Blackwell) received a diet of pure aphids (Rhopalosiphum padi (L)) until their first molt. The survivors were then raised to maturity on a mixed high-quality collembola diet. After random mating the procedure was repeated for another generation. A control line was run on collembola only. Survival, developmental and reproductive rates were measured for each generation. Compared to the control line the survival of the aphid-fed spiders increased significantly after only one generation of selection. It was not possible to detect any associated change either in development time or in reproduction. Consideration of groups differing only in the diet of their parents demonstrated a cost of tolerance to aphids. This may explain why high aphid tolerance has not evolved.
Benjamin, Suresh P., Institute of Zoology & Limnology, Dept. of Terrestrial Ecology and Taxonomy, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
On a species of the rare genus Epidius from Sri Lanka with notes on the Thomisidae palp (Araneae: Thomisidae).
The crab spider genus Epidius, established by Thorell (1891) for material collected in Celebes (Sulawesi), is one of the less known taxa of Thomisidae. This genus occurs in the tropics of the Old World and consists of some 9 species. Though they are fairly common (at least in Sri Lanka), detailed illustrations and information on their natural history are scanty. Members of this genus possess characters unusual for Thomisidae: bulbus longer than wide, "conductor" present, palpal femur and tibia elongated. Tibia with ventral/retrolateral tibial apophysis. Several specimens (male/female) were collected by beating from scrubs and flowering plants along the Bolgoda canal within the boundaries of the Bellanwila-Attidiya sanctuary, Colombo. They are identified with the widely spread Oriental species E. longipalpis (Thorell 1877), which is the only known species from Sri Lanka so far. Both sexes are illustrated here with notes on their natural history. This genus seems to be closely related to the genus CupaStrand 1906.The thomisid male palp ground plan is discussed. Accordingly the possession of a tegular structure that functions as a conductor is proposed to be plesiomorphic for this family.
Berendonck, B. and Lubin, Y., Mitrani Center for Desert Ecology, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Israel
Where does he get stuck? Position of the male embolus tip in the female genitalia after copulation in Latrodectus revivensis (Theridiidae).
In some spiders the apical sclerite (tip) of the male embolus breaks off during copulation and can be found lying within the female genitalia. It has been suggested that the embolus tip acts as a mating plug. In this study virgin males were allowed to mate with virgin females in the laboratory. After copulation we examined the male emboli and female genitalia with light microscopy and scanning electron microscopy. Additionally, mated females were obtained from the field and examined in the same way. The spiral embolus of male Latrodectus revivensis consists of the heavily sclerotized truncus, a membranous pars pendula and a terminal apical sclerite. The breaking point of the tip is marked by a distinct thickening at the proximal articulation of the apical sclerite. When the apical sclerite breaks during copulation only part of it lies inside the female sperm storage organ. The embolus tip extends from the heavily sclerotized end of the insemination duct, through the narrow opening of the spermathecal wall and into the posterior lumen of the spermatheca. The diameter of the apical sclerite inside the opening of the spermathecal wall is not much smaller than the diameter of the opening in which it is lodged. The embolus tip would act as a mating plug if its presence in the opening of the spermatheca prevents subsequent males from successfully ejaculating their sperm into the spermatheca. Whether this is the case remains to be examined.
Bodasing, M., Adams, N., Biology Dept., University of Natal, Private Bag X10, Dalbridge, Durban 4041, South Africa, Crouch, T., Durban Natural Science Museum, P.O. Box 4085, Durban 4000, South Africa and Slotow, R., Biology Dept., University of Natal, Durban, South Africa
Nest location of a social spider, Stegodyphus mimosarum (Araneae: Eresidae): thermal advantages during evening cooling.
Stegodyphus mimosarum are social spiders that share communal retreats and cooperate in nest building, nest maintenance and prey capture. Ability to capture and subdue large prey may be the most important factor leading to sociality in this species. This will be governed by prey availability, which in turn will be governed by nest location. We assessed distribution of nests within habitats and location within trees at Weenen Nature Reserve, KwaZulu-Natal (South Africa). Nests were placed non-randomly on the northern aspect of the tree. We performed an experiment to test whether this offers a thermal advantage to the spiders, by moving nests between the north and south aspects in a controlled manner. Nest on the north aspect of trees had significantly shallower cooling curves than those nests on the south aspect. There was no significant difference in heating curves. This may allow spiders to be active longer into cold winter evenings, or may enhance metabolic processes.
Bowie, Mike, H. andVink, Cor, J., Ecology & Entomology Group, Soil, Plant & Ecological Sciences Division, PO Box 84, Lincoln University, New Zealand
Comparison of the spider fauna in two field-boundary types in Canterbury, New Zealand.
Pitfall traps were used to monitor the predator species and numbers along a post and wire fence line and a hedgerow of the same field. Spiders were the most abundant predator group caught in fence pitfalls. The most common species caught in the fence pitfall traps were "Lycosa" hilaris Koch, Erigone wiltoniLocket and Lepthphantes tenuis (Blackwall). The most common species in the hedge pitfall traps were Misgolas parrotti (Forster) and two undescribed Theridiidae species. The greatest species diversity was found in the hedgerow (21 species, compared with 14 species along the fence line). The numbers of the four most common species were compared between the field and hedgerow over one year. The data indicate it is unlikely that spiders in New Zealand agroecosystems overwinter in hedgerows and migrate into fields in spring.
Cady, Alan B., Dept. of Zoology, Miami University - Middletown, Middletown, Ohio, 45042 USA
Changes of Argiope trifasciata locomotor activity, web parameters, and reproduction from sub-lethal exposure to malathion in soybeans.
Habitat disruptions result from standard, cyclical farming processes. Managing these agricultural practices to promote natural, endemic predatory arthropods, requires knowing the impact of these activities. Although resident spiders usually survive most chemical applications, laboratory tests on various spider families given sub-lethal doses of malathion show some dramatic behavioral alterations associated with locomotion and reproduction. Thus, although spiders may survive, they are behaviorally crippled. Argiope trifasciata was used to test for similar results in the field. Six 5m X 5m X 2m enclosures were erected in a soybean field and populated with marked spiders (10 per enclosure; 2 enclosures each for Control, Broadcast Spray, and Individually-dosed). After 30 days, treatment spiders were exposed to 10 ppm malathion; Broadcast spiders were sprayed in situ, while Individually-dosed ones were held in a jar for 24 hours with filter paper holding 10 :l of the 10 ppm dilution. All spiders were then measured until killed by frost. Treated spiders tended to increase locomotor frequency, but decrease duration so those exposed to malathion traveled shorter distances than controls. Dosed spiders made smaller, lower webs than controls, and treated spiders delayed laying eggs. Some were killed by frost before producing an egg sac. Thus, treated spiders had modified locomotion, web configuration, and probably had retarded reproductive development compared to controls.
Camp, E. A., Dept.of Zoology, University of Oklahoma in Norman. Norman, OK 73019, andGaffin, D. D., Dept. of Zoology, University of Oklahoma in Norman. Norman, OK 73019
Escape behavior in Paruroctonus utahensis mediated by phototaxic response.
While physiological studies indicate that scorpion eyes rival the best arthropod eyes (e.g. nocturnal moths) in absolute sensitivity, almost nothing is known about the effect of light on scorpion behavior. What little research has been done indicates that scorpions are negatively phototaxic. In this study we relate this photoresponse to a naturally occurring escape behavior in a psammophilic scorpion, Paruroctonus utahensis. Test subjects were allowed to choose light or dark regions of a circular arena under white light (WL) and infrared light (IR) conditions. Results of this experiment suggested that IR illumination was not useful for navigation in this setup, but could be used to provide illumination to film scorpion movements under both WL and IR with a low-light infrared sensitive camera. The above experiment was repeated with the addition of IR illumination to the WL treatments so that locomotory movements of both groups could be recorded. Movements under IR + WL were similar to those of the WL trials from the first experiment. Trace plots taken from video records indicated that scorpion movements were governed by our test-light conditions and not by other external sensory cues (e.g. geomagnetic, chemical). These results indicate that light plays a role in scorpion locomotion, producing an easily induced and highly predictable behavior. This reliable assay may be useful in the identification of the photoreceptors that govern locomotory behavior and in the examination of the integrative mechanisms important in visual information processing.
Chen, Jun, Institute of Zoology, Chinese Academy of Science, 100080, Beijing, China, Song, Daxiang, Dept of Biology, Hebei Normal University, 050016, Shijiazhuang, China, and Kim, Joo-pil, Dept. of Applied Biology, College of Life Resource Science, Dongguk University, 26, 3-ga, Pil-dong, Chung-gu, Seoul, 100-715, Korea.
Two new species and two new records of Chinese wolf spiders (Araneae: Lycosidae).
The present paper deals with two new species of the genus Evippa and the species Acantholycosa baltoroi (Caporiacoo, 1935) and A. lignaria (Clerck, 1757)newly recorded from China.
Coddington, J. A., Department of Entomology, National Museum of Natural History, NHB-105, Smithsonian Institution, Washington, D.C. 20560.
Progress in Spider Phylogeny (Arachnida: Araneae)
The 26 published quantitative cladistic studies are synthesized into a single, synergistic phylogeny spanning the entire Order Araneae, using a recently developed "supertree" technique that codes cladogram topology in matrix form for analysis under parsimony. The result is the first objectively derived cladogram of nearly all spider families and many subsidiary lineages. 449 spider taxa are included representing 102 of the 108 named families (Cryptothelidae, Cybaeidae, Cycloctenidae, Hahniidae, Halidae, and Homalonychidae are absent) and 13.7% of the 3,275 named genera. Criteria for inclusion in this synthesis were: 1) treatment of 3 or more higher taxa (genus or above); 2) an explicit taxon-character matrix; 3) quantitative analysis; and 4) peer-reviewed publication. The 26 studies shared taxa 654 times (327 instances), which constitute the means to combine the source cladograms. Parsimony analysis yielded 54 trees (ci = 0.97) that represented all combinations of a 2-, 3-, and 9-tomy, all minor and local rearrangements of taxa. The placement of Palpimanoidea is resolved among entelegynes, but problems persist among amaurobioids and lycosoids. Conflict or ambiguity among source trees occurred in Filistatidae, Eresoidea, amaurobioids, lycosoids, anyphaenids, araneoid families, and Linyphiidae. The cladogram includes 445 monophyletic groups, of which 200 are named formally or informally. Formal or informal names are mapped on the summary cladogram to provide an update on spider classification. The most detailed competing classification is 57 years old, not phylogenetic, and although it contains more names (462), as hypotheses of monophyly many of them are wrong.
Cornic, Jean-François, I.N.R.A. Unité de Recherches Forestieres, Mediterranéennes, Ave. Antonio Vivaldi, F-84000 Avignon, France
BAZAR: a spider database.
BAZAR was developed for my personal use as a reference data base. Its focus was extended a few years ago to all the fields involving Spider studies. The first by-product was files you can download from the Internet server of I.N.R.A. (http://www.irna,fr./USER/PRODUCTIONS/BDD/ARAIGNEES/ base-arafr.html) followed this year by the pars Araneae of the "Liste des travaux". The poster shows a sample of screen-computer copies with a range of questions you can ask BAZAR : from basic queries of files distributed via the WEB, to more sophisticated questions like: 1 - who is who? 2 - who eats who? 3 - special forms with drawings for tentative identification of species belonging to a known genus from a given country 4 - the use of a wide range of keywords. A demonstration version of BAZAR will be available on a computer if you want to try and ask your own questions. Before quitting BAZAR you will be welcome to leave comments, remarks and questions thanks to a special electronic form. Concluding remarks: BAZAR is much more developed than this demonstration, especially for the Drawings. The new release will be on the WEB in August 98, and will probably be the last "free" one. To have access to future releases, a time-limited password will be needed and delivered upon request and with a gentleman's agreement to provide me with new papers.
Cutler, B., Microscopy Laboratory and Dept. of Entomology, University of Kansas, Lawrence KS 66045-2106, U.S.A., Guarisco, H., P. 0. Box 3171, Lawrence 66046, and Mott, D. I., Dept. of Biological and Physical Sciences, Lincoln Land Community College, 5250 Shepherd Road, Springfield IL 62794-9256
Ontogeny of characteristic spine development in Mimetus (Araneae, Mimetidae).
The distinctive prolateral spination of the metarsi and tibiae of the first two legs in Mimetus isobscure in the first post-eggsac eclosion instar. Only one of the small, acuminate tipped spines appears in the first instar, small spine numbers increase in the second instar, and outnumber the large spines by the third instar. The high variability noted in adult spine counts occurs in the third instar as well. The characteristic spines have a socketed base and longitudinally grooved shafts. The large spines are characterized by numbers of small pustules on the base below the emergence of the shaft and the tips of the spines are round. The small spines have fewer pustules or none, and the tips of the spines are falcate or acuminate. Both the large and small spines morphologically resemble presumptive mechano-receptive setae on the legs, and the spines may have a sensory function.
de Armas , Luis F., Instituto de Ecologma y Sistematica, Apartado Postal 8029, La Habana 10800, Cuba
The Greater Antillean scorpions (Arachnida, Scorpiones).
The West Indian scorpiofauna contains 69 described species, which belong to 3 families (Buthidae, Diplocentridae, and Ischnuridae), and 12 genera. Eleven of these genera and 60 (86.9%) of the species are present in the Greater Antilles (Bahamas, Cuba, Hispaniola, Puerto Rico, Virgin Islands, Jamaica, and Cayman Islands). The buthid genera Alayotityus and Tityopsis are only known from Cuba, whereas all non-Asiatic species of the diplocentrid genus Heteronebo are Greater Antillean ones. The only non-endemic species are the buthids Centruroides gracilis (Latreille), C. guanensis Franganillo, and Isometrus maculatus (De Geer). Unpublished data shows that with independence of some synonymous, the Greater Antilles has a richer scorpiofauna than currently known (at least 10 new species have been mentioned from Hispaniola and Cuba). The Antillean species of the genera Tityus, Microtityus, Rhopalurus, and Opisthacanthus, are of South American origin; whereas those of Didymocentrus, and perhaps Centruroides, are Central American. The genera Cazierius,Alayotityus, and Tityopsis, are endemic. The highest diversity is found in south Hispaniola and southeastern Cuba, where about 55% of the West Indian species are present.
Edwards, R. L., Res. Assoc. USNM, Box 505, Woods Hole, MA 02543
A new species of Disembolusfrom the coastal zone of the northeastern part of the United States.
The genusDisembolus is one of the group of small erigonine genera that are all too often described from single individuals and with little or no life history information. The new species described here is common on the sandy beaches and dunes just above high tide levels adjacent to the salt and brackish water marshes of Cape Cod, Massachusetts and Long Island, New York. Life history and habitat data are given. The genus is apparently found only in North America and was revised by Millidge in 1981, who recognized 22 species at that time.
Edwards, W. R., Dept. of Biology, Western Carolina University, Cullowhee NC 28723
A comparison of the effectiveness of three ground spider sampling techniques in an old growth hemlock forest.
Methods used to inventory biodiversity should maximize the ratio of species yield to sampling effort as much as possible. This study compares the effectiveness of three methods commonly used to inventory ground spiders: 1) manual ground sampling, 2) Tullgren funnel extraction of leaf litter, and 3) pitfall trapping. Samples were collected in an old growth hemlock forest in the Great Smoky Mountains National Park every two weeks from March through October 1997. The total sample size of 48 1-hour ground samples, 48 1m2 litter samples, and 96 baffled pitfall samples represented approximately 48 person-hours of collecting effort per method. An ANOVA indicates that method has a significant effect on the number of species (mean ± std. error = 6.25 ± 0.41 for ground, 9.17 ± 0.43 for litter, and 3.15 ± 0.29 for pitfall samples) and adults (15.08 ± 1.39 for ground, 42.50 ± 4.10 for litter, and 6.56 ± 0.92 for pitfall samples) collected per 1 hr of sampling effort. Complimentarity values are 59% for ground vs. litter, 62% for ground vs. pitfall, and 60% for litter vs. pitfall. Ground sampling yielded a total of 49 species, litter extraction 48 species, and pitfall trapping 36 species, and the number of species unique to each method was 15, 11, and 5, respectively. For each method, 35-45% of the species were linyphiids, with erigonine species comprising a higher portion of linyphiid species in litter (81%) and pitfall (87%) than in the ground samples (67%). A much higher portion of pitfall-trapped adults were males (75%) than was true for the ground (25%) and litter (23%) samples.
Fet, V., Dept. of Biological Sciences, Marshall University, Huntington, WV 25755
Basal node in the scorpion phylogeny is confirmed by 18S ribosomal RNA sequence data.
Nucleotide sequence analysis of the conserved, slowly evolving 18S (SSU, or small subunit) ribosomal RNA gene became a powerful tool in resolving high-level animal phylogeny issues. We report the first available data on the comparison of 18S rRNA gene DNA sequences from six taxa of scorpions (Arachnida, Scorpiones) belonging to five families (Buthidae, Ischnuridae, Iuridae, Scorpionidae, and Vaejovidae). The observed variation along 1120 base pairs of this extremely conserved gene was below 6% (94% similarity); two Buthidae sequences (genera Androctonusand Centruroides) differed 1.3% from each other. The same distance separated two "chactoid" families (Vaejovidae and Iuridae) which belong to a well-supported monophyletic clade. Distance between Buthidae and "chactoids" was 5.4 to 5.6%. The outgroup (a solpugid Eusimonia) was 10.7 to 11.2% distant from scorpions. Most parsimonious phylogenetic trees (built in PAUP 3.1.1) clearly confirm the basal node ("split") in scorpion phylogeny known from the morphological and toxicological data. 18S rRNA data show that the family Buthidae (the most diverse and successful existing family) and all other extant scorpions (four "non-buthid" families) form two independent, deep clades.
Ferrier, S., New South Wales National Parks and Wildlife Service, PO Box 402, Armidale NSW 2350, Australia., Gray, M., Australian Museum, 6 College Street, Sydney NSW 2000, Australia, and Cassis, G., Australian Museum, 6 College Street, Sydney NSW 2000, Australia
Spatial patterns of species turnover in ground dwelling spiders and insects in eastern Australia: implications for selection of forest conservation reserves.
Ground dwelling spiders, beetles and ants were surveyed at 239 forest sites in north-east New South Wales. The level of dissimilarity (or turnover) in species composition between these sites is analyzed in relation to inter-site differences in a number of remotely mapped environmental and vegetational variables and inter-site geographical separation. Results of this analysis are compared with those obtained from analyses of vertebrate and vascular plant species turnover in the region. Biological dissimilarity between sites is correlated with inter-site environmental differences for all surveyed invertebrate, vertebrate and plant groups. However, after controlling statistically for environmental differences, correlation between biological dissimilarity and inter-site geographical separation is much stronger for ground dwelling spiders and insects than for vertebrates and plants, suggesting that these invertebrates exhibit a higher level of gamma diversity. These results have important implications for the use of remote vegetation or environmental mapping as a surrogate for selecting reserves to conserve biodiversity. To reserve regional biodiversity in a biological group exhibiting high gamma diversity it is imperative that a reserve system not only include a sample of each mapped environment or vegetation class but that this sample is spread geographically to accommodate species turnover within the class.
Gantenbein, B., Inst. Zool., Div. of Population Biology, Baltzerstrasse 3, CH-3012 Berne, Braunwalder, M. E., Arachnodata, Frauentalweg 97, CH-8045 Zurich, and Scholl, A., Inst. Zool., Div. of Population Biology, Baltzerstrasse 3, CH-3012 Berne, Switzerland
Allozyme studies on scorpions from Morocco and from the Aegean Region.
We analyzed the population genetics of Buthus occitanus (Amoreux, 1789) and Mesobuthus gibbosus(Brulle 1832) ) (Scorpiones: Buthidae) using horizontal starch gel electrophoresis of allozymes (17 loci scored). This study includes population samples of B. occitanus from Morocco (ssp. mardochei and ssp. paris), Tunisia (ssp. tunetanus), and Spain (ssp. occitanus). Samples of M. gibbosus were collected from the Balkan (Greece), the Peloponnesos (Greece), Anatolia (Turkey), the Hellenic Arc (Crete, Rhodos), and from the Island Cyprus. A sample of Androctonus mauretanicus (Pocock, 1902) (Buthidae) from Morocco was included for comparison. Euscorpius flavicaudis(De Geer, 1778) (Chactidae) from Lauris (France) served as reference for the electrophoretic mobilities. Generally, the observed genetic variability within populations was low. The UPGMA phenogram shows a low genic differentiation among the B. o. mardochei and B. o. paris samples from Morocco, whereas B. o. tunetanus is more differentiated and the B. o. occitanus from Spain clearly branches off at a considerably higher distance. The genic differentiation among M. gibbosus samples is not consistent with the proposed taxonomy (Kinzelbach, 1975). The samples from Greece (ssp. gibbosus) and from the south coast of Turkey (all ssp. anatolicus) form a cluster at a low genetic distance. The Cyprus population (ssp. anatolicus) is more isolated. The sample from Central Anatolia, however, is unexpectedly highly differentiated and branches off from the M. gibbosus cluster at about the same distance level where A. mauretanicus sorts out from the other Buthidae.
Gnaspini, P., Departamento de Zoologia, Instituto de Biociencias, Universidade de São Paulo, Cx. P. 11461, 05422-970 São Paulo, Brazil
Postembryonic development of Goniosoma sp., with comments on the use of developmental and morphometric characteristics for the recognition of species among harvestmen (Arachnida: Opiliones: Gonyleptidae).
The morphometric characterization of the postembryonic stages of an undescribed species of Goniosomaaff. badium is here presented. For this characterization, for each nymphal stage, the number of tarsal segments was counted, and the body width, body length (up to the end of the thorax), total length of the pedipalp and of the walking legs were measured. These data are compared to those of G. spelaeum. Morphometric data from males of six species of Goniosomaare also presented and discussed. Data presented show that some characters and their variation may be used to recognized different species among themselves or different instars of the same species. Others, however, overlap, and are not useful for species (or instar) characterization. Therefore, all data presented show a need of the use of intraspecific variation during descriptions of harvestmen. Moreover, the lack of recognition of developmental stages may lead to confusing characterization of ranges of variation of alleged adults.
Gonzalez, A. P. y de Armas, L. F., Departamento de Invertebrados, Instituto de Ecologia y Sistematica, A.P. 8029, C.P.10800, Habana 8, Cuba
Nueva especie del genero Kimula(Opiliones : Minuidae) de Republica Dominicana.
El ginero antillano Kimula Goodnight et Goodnight, 1942, agrupa actualmente a siete especies vivientes distribuidas en las islas de Puerto Rico (K. elongata Goodnight et Goodnight, 1942), Cuba (K. tuberculata Goodnight et Goodnight, 1943; K. levii Silhavy, 1969; K. banksi Silhavy, 1969; K. goodnightorumSilhavy, 1969; K. turquinensis Silhavy, 1969; y K. botosaneanuiAvram, 1973) y St. John (Islas Virgenes) donde se ha seqalado la presencia de una nueva especie aun sin describir. Se estudio un lote de opiliones procedente de la coleccion de invertebrados dominicanos, colectados en, Casabito, Constanza, provincia La Vega, Republica Dominicana, que se encuentra depositado en el Instituto de Ecologia y Sistematica (IES) del Ministerio de Ciencia, Tecnologia y Medio Ambiente , La Habana, Cuba. El estudio arrojo la presencia de una nueva especie para la ciencia de Kimula. Es la primera especie viviente del genero descrita de La Espaqola y muestra dos caracteres que se presentan por primera vez dentro del genero: Una espina media de las areas I y II y la presencia de tuberculos en la superficie dorsal del femur palpal; estos caracteres permiten separarla claramente de las restantes especies conocidas. El tamaqo y el tuberculo romo del trocanter IV del macho permiten relacionarla con K. turquinensis y la apofisis del esternito libre IV del macho es muy parecida a la de K. elongata.
Gorlov, I. P., Dept. of Biol., Fac. of Educ., Tottori Univ., Tottori, 680-8551 Japan and Inst. Cytol. and Genet., Siberian Branch of Russian Acad. of Sci., Novosibirsk, Russia, and Tsurusaki, N., Dept. of Biol., Fac. of Educ., Tottori Univ., Tottori, 680-8551 Japan
Population cytogenetic analysis of a hybrid zone between two chromosome races of Gagrellopsis nodulifera (Opiliones: Phalangiidae).
We have studied a hybrid zone between two chromosome races, 2n=16 and 2n=22 of a Japanese harvestman Gagrellopsis nodulifera Sato and Suzuki (Phalangiidae). The hybrid zone (width 5-10 km) is located in the Chizu area, eastern part of Tottori prefecture, Western Honshu, Japan. We found that in most hybrid populations frequencies of intermediate homozygotes with 2n=18 and 2n=20 are much higher, whereas the frequencies of karyotypic heterozygotes (especially di- and tri-heterozygotes) are lower than one can expect. The more trivalents a karyotype retained, the higher its deficit was. Anomalous segregation of trivalents and chromosomes unusually rearranged were found in meiosis of heterozygotes. Different karyotypes are non-randomly distributed across the hybrid zone. Three single heterozygotes (2n=17, 2n=19 and 2n=21) and the intermediate homozygotes (2n=18 and 2n=20) form a series of successive peaks along a transect trough the hybrid zone. Such specific distribution of karyotypes is most likely a result of spatial separation of clines for 3 chromosome rearrangements differentiating parental races. We have also found that 2n=22 chromosomal race tends to occupy altitudes above 700 m, whereas 2n=16 chromosomal race occupies altitudes below 600 m. The hybrid populations occur on the intermediate altitudes.
Guarisco, H., Kansas Biological Survey, University of Kansas, Lawrence, KS 66047
House spiders of Kansas.
Spiders found in edificarian habitats, may be divided into three categories: 1) true synanthropes, which can establish breeding populations in houses, seldom occur locally in the natural environment, and have broad ranges because they may be accidentally transported to new locations. 2) Spiders which are seasonally abundant in natural habitats as well as in houses. They don't establish breeding populations in houses. 3) Spiders which are rarely found in houses, because they are locally rare, or locally common but are rarely found indoors. Fifteen species are true synanthropes in Kansas, including Loxosceles reclusa Gertsch and Mulaik and Cheiracanthium mildei L. Koch. Category 2 contains 26 species, including Latrodectus hesperus Chamberlin and Ivie, L. mactans (Fabricius), and L. variolus Walckenaer. There are 33 species which are rarely found indoors in Kansas. Most species have been reported from houses across the U S.
Halaj, J., Cady, A. B., Dept. of Zoology, Miami University, Oxford, OH 45056, and Uetz, G. W., Dept. of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221-0006
Enhancement of spider and harvestman populations via habitat manipulations (straw refugia) in soybeans.
Promoting generalist predatory arthropods as indigenous natural enemies of insect pests has potential for efficient biological control maintaining pest populations in agroecosysyems. We investigated the use of straw shelters as temporary refugia to enhance the population size of ground-dwelling spiders and harvestmen in a soybean ecosystem. Modular habitat refugia consisted of baskets fabricated from chicken wire (0.5 x 0.8 x 0.2 m) loosely filled with bedding straw. They were positioned in the field one week before and then immediately after tillage, and were subsequently sampled at five-week intervals until after harvest. From 5 to 37 times more spiders, and 2 to 80 times more harvestmen were hand-collected from the refugia compared to the open field. Furthermore, the presence of these habitat shelters enhanced spider egg sac production 7 to 32 times, and almost tripled the spider species richness (17 vs. 47 species). Soybean seedlings within 20 cm of refugia suffered significantly less insect damage (33% less) than open field plants, and the yield (seed biomass) was enhanced by 21%. We suggest that this simple habitat manipulation may promote large-scale establishment and reproduction of a diverse generalist predatory arthropod assemblage in agroecosystems, leading to biological control rooted in the endemic natural predators.
Hall, Grace, Landcare Research, Private Bag 92170, Auckland, New Zealand
Golden orbweb spider in New Zealand.
The large golden orbweb spiderNephila edulis (Koch), from Australia, occurs in New Zealand occasionally. First recorded here in 1975, these spiders turn up every few years, usually only one or two at a time. However in some years large numbers have turned up, and 1996-97 was one of those years. Large mature females up to 4 cm in body length are noticed at the end of summer (March/April) when their webs reach up to 2 meters across and appear golden in the sunlight. Females often deposit a large fluffy egg sac of golden yellow silk in the corner of the web in autumn, and usually die off at the beginning of winter. Egg sacs have been kept under observation and all have turned out to be infertile. No males have ever been found here, although in Australia tiny males can be seen on the edge of the web. These spiders are chance occurrences here, being windblown across the Tasman as young spiderlings. If the males make the journey too, they must be too few and too widely dispersed to find the females. The golden orbweb spider is widespread in Australia, occurring in Western Australia, New South Wales, Queensland, and on islands of the Great Barrier Reef.
Harland, Duane, P., Dept. of Zoology, University of Canterbury, New Zealand
Perception of the orientation of dangerous prey by Portia, tropical araneophagic jumping spiders.
Portia is a genus of araneophagic web invading salticids with a particularly complex predatory strategy. Perception of prey spider orientation and how this affected stalking behavior in species of Portiawas investigated. It was found, by observing controlled predatory sequences without established webs, that Portia tended to attack the web spider Badumnafrom behind and above. Special behaviors, such as detouring, waiting for an opportunity, and twisting during a leap, were used by Portia to strike and grip its preferred target area; the dorsal-posterior edge of the carapace. However, with Pholcus phalangioides under similar conditions no consistent target area was observed and Portia instead tended to align itself with a gap in the legs wide enough to pass through and strike the body. It is concluded that: i) Portia pays attention to prey spider orientation; ii) modifies its behavior accordingly; iii) that different types of prey spider involve different use of orientation information.
Harwood, J. D., Cardiff School of Biosciences, University of Wales Cardiff, P.O.Box 915, Cardiff. CF1 3TL. U.K., Symondson, W. O. C., Cardiff School of Biosciences, University of Wales Cardiff, P.O.Box 915, Cardiff. CF1 3TL. U.K. and Sunderland, K. D., Horticulture Research International, Wellesbourne, Warwick. CV35 9EF. U.K.
The development and characterization of antisera to detect predation by spiders on non-pest food resources in cereal crops.
Invertebrate biodiversity within arable crops encourages increased numbers of predators which might be expected to help control pests such as aphids. However, biodiversity also increases the diversity of available prey. Our aim was to determine whether non-target prey, such as Diptera, divert predators from feeding on pests, and hence reduce biological control, or, by retaining larger numbers of predators within the crop, improve such control and help increase predator fecundity by providing a varied diet. A polyclonal antiserum was first developed for use in evaluating predation by spiders on Diptera, an abundant food resource in cereal fields. The antiserum will be used to quantify predation by use of enzyme-linked immunosorbent assay (ELISA). Two rats were immunised with phorid (Diptera: Phoridae) antigens. A third rat was maintained for production of normal rat serum. The antiserum was tested against a range of alternative prey items and proved to be more specific than a previous antiserum raised in a rabbit against a mixture of antigens from a range of Diptera species. It was also more sensitive in detecting Drosophila melanogaster antigens in the guts of spiders. Following absorption against Aphididae, specificity was improved and the antiserum was considered to have potential for use in predator-prey studies. The rates at which D. melanogaster antigens decayed in the gut of Erigone dentipalpis is displayed and discussed in relation to the quantification of predation. The problems associated with polyclonal antisera are discussed and improvements to the procedure suggested.
Hoenen, S. and Gnaspini, P., Departamento de Zoologia, Instituto de Biociencias, Universidade de São Paulo, Cx.P. 11461, 05422-970 Sao Paulo, Brazil
Activity rhythms and behavioral characterization of epigean and cavernicolous harvestmen (Arachnida: Opiliones).
The activity rhythms, feeding behavior, and reaction to light of two epigean species of harvestmen (Iporangaia pustulosa and Iguapeia melanocephala) and of one cavernicolous species (Pachylospeleus strinatii) have been recorded. Continuous records of activity rhythms were made using a system which detects vibrations and sends the data to a computer. The feeding behavior was observed once a week when the animals were fed with pieces of coleopteran larvae. Tests of reaction to light were conducted in a box apparatus. When the light was switched on, the time elapsed for the animal to start walking and the total distance walked have been measured. Both the epigean and the cave species showed a highly pronounced circadian rhythm. Whereas the epigean species used to carry the food back to their shelters in order to feed, the cave species fed where it found the food. The time of reaction to light did not differ statistically between species. However, the cave species used to walk much larger distances after it started walking. These differences are probably due to cave evolution. The cave species should have to wander searching for food (and maybe mates) because of the scarcity of food, showing very intense activity. Therefore, any given stimulus causes its start of activity. Moreover, it walks more and feeds wherever it finds food.
Holah, J., Dept. of Botany, University of Kansas, Lawrence, KS 66045, Smith, E. F. and Smith, D. R., Dept. of Entomology, University of Kansas, Lawrence, KS 66045
Mitochondrial COI and COII sequences of arachnid orders and other chelicerates (or, "It seemed like a good idea at the time.")
We sequenced a ~300 base portion of the mitochondrial genome extending from the 3' end of cytochrome oxidase I (COI) to the 3' end of cytochrome oxidase II, in representatives of the Xiphosuridae, Acari, Amblypygida, Araneae, Opiliones, Pseudoscorpiones, Scorpiones, Solpugida, Thelyphonida, and Pycnogonida. We selected this region because we suspected it revealed a gene rearrangement that might be a synapomorphy for chelicerates. In insects, it is known that a leucine tRNA gene lies between COI and COII. We found this tRNA gene was absent from this position in all the chelicerate taxa we examined; COI and COII were adjacent or separated by a few non-coding bases. However, a recently published study showed that the insect condition is shared with crustaceans (but not myriapods), and suggests that the condition in chelicerates may be a symplesiomorphy.
Holmberg, R. G., Natural and Human Science, Athabasca University, Athabasca, AB, T9S 3A3, Canada
Harvestmen (Opiliones, Palpatores) of the prairie provinces of Canada.
In Alberta, Saskatchewan and Manitoba, there are 10 species of harvestmen in three families. They are: Sabaconidae: Sabacon new species; Sclerosomatidae: Leiobunum calcar(Wood 1868), Leiobunum vitattum (Say 1821), Nelima paessleri(Roewer 1910), Togwoteeus biceps (Thorell 1877); Phalangiidae: Liopilio glaber Schenkel 1951, Odiellus pictus (Wood 1868), Opilio parietinus (DeGeer 1778), Phalangium opilio Linnaeus 1758, and Paroligolophus agrestis (Meade 1855). There are eight ecozones represented in these provinces, but only the southern four have been fairly extensively sampled for arachnids. P. agrestis is introduced but is only known from one location in the study area. N. paessleri and L. glaber are restricted to the Montane Cordillera but all other species are found in two or more ecozones. The most commonly collected species are P. opilio, T. biceps, andO. pictus. P. opilio occurs mainly in disturbed and cultivated areas. O. parietinus occurs in similar habitats as P. opilio but is collected infrequently. T. biceps occurs primarily in the Prairie ecozone but is also found in the Boreal Plains. O. pictus occurs in the Boreal Plains and the Boreal Shield. L. calcar and L. vittatumare only found in the eastern part of the study area.
Kim, Joo-pil, Dept. of Applied Biology, College of Life Resource Science, Dongguk University, 26, 3-ga, Pil-dong, Chung-gu, Seoul, 100-715, Korea
The spider fauna of Keojae-do, Korea.
The spider fauna of Keojae-do in the south of Korea was investigated. As a result, the author presents a list of 116 species, 71 genera, 25 families and describes 2 species, newly known in Korea. All specimens are deposited in the Arachnological Institute of Korea.
Klee, G. E., Dept. of Biological Sciences, Kent State University - Stark Campus, 6000 Frank Ave., NW, Canton, OH 44708
Leaf litter and forest understory species of N. American harvestmen as scavengers and predators in roadside, agricultural and urbanized environments (Arachnida: Opiliones).
In the course of ongoing field surveys of both nocturnal and daylight active Opilione predation on various arthropods, several species were found to be quite numerous in previously unreported and unusual habitats. One novel habitat type was the bases of lighted interstate highway signs; 3 harvestmen species were collected in significant numbers during regular nocturnal collections in Northeastern Ohio from July through September, 1990, and in other collections in subsequent years. The harvestmen were apparently drawn to these areas by the many insects and other arthropods attracted to these lighted signs, which in some cases were as much as 50 meters from typical mesic hardwood forest habitats from which the most frequently collected species, Leiobunum vittatum, has most frequently been reported. A laboratory maintenance technique for L. vittatumand another opilionid species, Hadrobunus maculosus, will also be described, and compared with one previously published by the author on Phalangium opilio .
Koponen, S., Zoological Museum, University of Turku, FIN-20014 Turku, Finland
Ground-living spiders in old taiga forests, Finland.
Spiders living on the forest floor in six old taiga forests were studied using pitfall traps in 1994 (in Suomussalmi) and 1995 (in Puolanka), central-eastern Finland, ca. 65°N. Seventy-seven species belonging to eleven families were caught. Linyphiidae (s. lat.) dominated both in species and individual numbers. The most common species were Lepthyphantes alacris, Agyneta ramosa, Lepthyphantes antroniensis, Centromerus arcanus and Agyneta subtilis. The fauna found is, in general, typical of old Finnish boreal forests.
Kuntner, M., and Sket, B., Dept. of Biology, Biotechnical Faculty, University of Ljubljana, P.P. 2995, SI-1001 Ljubljana, Slovenia
A comparison of the respiratory system in cave and surface species of spiders (Araneae: Dysderidae)
A hypothesis that in the hypogean species the respiratory system can be subject to regressive evolution was tested in representatives of the spider family Dysderidae. The examined epigean species from Slovenia were Dysdera ninnii Canestrini 1868, and Harpactea lepida (C. L. Koch 1838), the hypogean were Stalita taenariaSchiödte 1847, and Parastalita stygia (Joseph 1882). Both tube tracheae and book lungs were investigated and measured and a number of indexes for comparing the structures between species were invented. D. ninnii had a well developed tracheal system as well as book lungs. Both Slovenian troglobites showed similarly less developed respiratory systems compared to D. ninnii. H. lepida surprisingly had a markedly less developed respiratory system compared to D. ninnii and in some cases even to both cave species. Additionally three epigean and four hypogean dysderid sister species from the Canary Islands were examined. These species, albeit in statistically too small numbers for any significant results, with few exceptions confirmed speculations that the respiratory system in hypogean species is subject to reduction.
Lawrence, K. L. and Wise, D. H., Dept. of Entomology, University of Kentucky, Lexington, KY 40546
Response of spiders to enhanced input of detritus to the forest-floor food web.
Previous research by Chen and Wise found that adding high -quality detritus (chopped mushrooms and potatoes, and fruit fly medium) to open field plots increased densities of Collembola and fungivorous Diptera 3x and 2x, respectively. These effects propagated through the food web, resulting in a 2-fold increase in spider densities, suggesting that spiders in the litter layer are food-limited. We expanded upon the design of this experiment to answer two questions: 1) what are the relative contributions of changes in aggregation and reproduction to the overall numerical response of spiders to increases in prey density, and 2) how do spider populations respond to a lower rate of resource supplementation? Twenty 2 x 2-m plots were randomly assigned to one of four treatments: open + food; open, no food; fenced + food; and fenced, no food. For four months we supplemented the resource base at 44% the rate of Chen and Wise. Surprisingly, food enhancement did not increase spider density or biomass, nor did densities of Collembola and fungivorous Diptera increase. Because the average amount (dry Wt/M2) of natural litter in our plot was 60% greater than Chen and Wise, our rate of supplementation was only 25% the rate of Chen and Wise when expressed as a fraction of the standing crop of litter. We will discuss hypotheses relating to variation in the strength of abiotic and biotic limiting factors that might explain the strikingly different responses to resource supplementation in the two studies.
Logunov, D. V., Siberian Zoological Museum, Institute for Systematics and Ecology of Animals, Frunze Street - 11, Novosibirsk 630091, Russia
A redefinition of the genusMarpissa C. L. Koch, 1846 (Araneae, Salticidae).
The genus Marpissa is redefined based on both the detailed structure of the genitalia and somatic morphology. Hyctia Simon, 1878 (nivoyi, pikei, etc.) is shown to differ from Marpissa (s. str.; muscosa species group), in the body shape only and seems to approve a subgeneric rank. Marpissa canestrini and related species (pulchra, nobilis, etc.) are proven to approve a rank of a separate (new !) genus distinguished from true Marpissaby the following characters: male maxillae lack a lateral hook-shaped outgrowth (present in Marpissa); epigyne with the median septum (absent in Marpissa); tube-receptacles equal or twice as long as the insemination ducts (5 or more times longer in Marpissa); cymbium of usual form, never flat (flat and rounded, often curved apically in Marpissa); distal tegular protuberance (sensu Griswold, 1993) absent (present in Marpissa); proximal position of the embolic base (apical position in Marpissa); and embolic revolution less than 180 degrees (ca. 360 or more degrees in Marpissa). Refined definitions, affinities and complete synopsis of both Marpissaand a new genus are provided; all the diagnostic characters are figured and discussed. Distributions of both genera are briefly discussed as well.
Lourenço, W. R., Laboratoire de Zoologie (Arthropodes), Museum National d'Histoire Naturelle, 61 rue de Buffon 75005 Paris, France, Goodman, S., Dept. of Zoology, Field Museum of Natural History, Chicago, Illinois 60605, and World Wide Fund for Nature, BP 738, Antananarivo 101, Madagascar
Diversity and endemism in Madagascan scorpions.
Contributions to the knowledge of the scorpion fauna of Madagascar began with descriptions of species by Gervais (1844) Pocock (1890, 1894), Kraepelin (1896, 1901) etc. Fage (1929) published the first monographic study of the group, which was a comprehensive work for the period in which it was produced. However, both Fage (1929) and Millot (1948) largely overestimated the extent of contemporary knowledge of Madagascar's fauna. In fact, as with most zoological groups, when more species are described and the group appears to be well known, further smaller species begin to be recorded and described, and the average body size of the group is reduced (Fenchel, 1993; Blackburn & Gaston, 1994). Since 1995, the discovery and description of several new taxa in Madagascar (Lourenço, 1995, 1996a,b,c,d 1997, in press; Lourenço & Goodman, in press) refer, in most cases, to microscorpions. In this poster our aim is to present a clear view of the diversity importance and endemic levels of Madagascan scorpions.
Maupin, J. L., and Riechert, S. E., Dept. of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996-1610
Tests for differences in superfluous killing behavior among spider populations.
Superfluous killing is the capture of prey in amounts that exceed the consumptive capabilities of the predator. Although this behavior appears to be maladaptive, it has been observed in several spider species, including the funnel web spider Agelenopsis aperta. We examined four populations of A. aperta occupying different feeding environments and degrees of isolation (desert grassland, evergreen woodland, desert riparian with gene flow from woodland, desert riparian with no gene flow) to determine the extent to which superfluous killing behavior is adapted to local conditions. In the field and lab, we measured the mass of prey captured when unlimited numbers of prey were provided. We compared these values with optimal prey consumption levels, measured in lab trials. Although each population exhibited some superfluous killing in the lab trials, we found significant differences among populations in the amount of prey killed and in the mass of prey consumed. Individuals from the well-fed pure riparian population killed and consumed less than did members of the other populations. The desert grassland population exhibited the highest consumption levels. With the exception of the riparian population with no gene flow, all populations killed some prey that they did not feed on at all. The results support the predictions made based upon environmental conditions and genetic influences surrounding these populations.
Mikhailov, K. G., Invertebrates, Zoological Museum, Moscow State University, Bolshaya Nikitskaya Street 6, Moscow 103009, Russia
Zoogeography of the spider genus Clubiona Latreille, 1804 (Aranei, Clubionidae) in the Palearctic.
117 distribution ranges of Palearctic Clubiona species are analyzed. Main species diversity centers, namely European and Manchurian, are established. A system of distribution patterns is proposed. Basic distribution ranges are Manchuriocentric (73 species), Eurocentric (31 species), Kazakhstano-Mongolian (5 species), Caucasian (4 species), Middle Asian (2 species), and Siberio-American (2 species). The genus is shown to be mostly connected with nemoral (broadleaved) forest zone. It is almost totally absent in deserts, being rather rare in true tundra and steppe biotopes.
Mikhailova, E. A., Chair of Zoology, Moscow State Pedagogical University, Kibalchica Street 6, Bldg 5, Moscow 129278, Russia
Altitudal and biotopic distribution of herpetobiont spiders of the central part of the Caucasus Major northern macroslope: first results.
Detailed quantitative investigation of Caucasian spiders is made for the first time. Current project includes a study of the fauna, distribution and zoogeography of spiders (mostly herpetobiont) of a model area, namely North-Ossetian State Reserve, together with its environs. Spiders of the Main (Glavniy) Mt. Ridge, as well as of several lower parallel ridges (Skalistiy, Kabardino-Sunzhenskiy) are studied. Material was collected by pitfall traps in 1985. A preliminary study is conducted on the spider family level. Dominant structure, altitudinal and biotopic distribution are examined. Lycosidae are dominant in open communities of subalpine and steppe belts. Their share is lower in forests, whereas Dysderidae are the most abundant there. Percentage of Linyphiidae is minimal in steppe and open xerophytic communities, and it is higher in forests. Gnaphosidae share is lower in forest communities, than in open ones. In subalpine zone, communities of different microslopes (northern and southern) differ crucially.
Moon, M. J.,Jeong M. J., Dept. of Biological Sciences, Dankook University, Cheonan, 330-714, Korea, and Kang, C. S., Department of Life Sciences, Hoseo University, Asan 337-850, Korea
Molt-related changes of the integument wound healing responses in the wolf spider, Pardosa astrigera.
This study was initiated to examine the effects of molt during the wound healing process of the integument, which composed of outer cuticle and inner epidermal cells. Artificial wounds were induced by punching with a sharp needle prior to three days before molting. Then molt-related changes on the integument were morphologically observed, and compared to those of inter-molt spiders. The wounds of the inter-molt individuals were gradually healed according to the following processes: coagulation and wound plug formation by hemocytic migration, and regeneration of the epidermal cells and secretion of a new cuticle. However, according to the fine structural analyses using electron microscopic examination, the healing period required to wound repair was shortened dramatically. Moreover, responses healing the wounds were also accelerated during the molting period. Therefore, hemocytic migration and reconstruction of the epidermal cell layer, which completed nearly 10 to 12 days after wounding at inter-molt individuals, were accomplished within 3 days at molting spiders.
Moon, M. J., Dept. of Biological Sciences, Dankook University, Chonan City, 330-714 Korea, and Tillinghast, E. K., Dept. of Zoology, University of New Hampshire, Durham, NH 03824
Fine structural analysis of glandular epithelial changes during silk production in the barn spider, A. cavaticus.
Synthesis of protein by the major ampullate silk glands in the barn spider, Araneus cavaticus was stimulated by depleting the storage of silk protein in the ampulla by mechanically pulling fiber from the spigot. After this stimulation, fine structural changes of the glandular epithelium during silk production were examined using transmission electron microscope. Secretory silk was synthesized from rough endoplasmic reticulum (rER) of glandular epithelial cells, and was transported from the rER into the secretory vesicles which were grown up by fusion with the surrounding small vesicles including the secretory silk. The mature secretory product in glandular epithelium appeared almost spherical vacuoles of no more than 3 mm in diameter. The Golgi complex did not seem to play an important role in the process of secretion. In contrast to the secretory epithelium of the pre-extruding stage, the epithelium of the post-extruding stage was composed of a thinner layer of tall columnar cells with less definitive cell membranes. There were few secretory droplets within these cells, thus causing this region to stain much lighter. It was obvious that the cell loses part of its cytoplasm in this process. Disorganization of the secretory product occurred when it was extruded from the cells by an apocrine process.
Ng, M. Y., Dept. of Ecology, Evolution and Behavior, University of Minnesota. St. Paul, MN 55108
Spiders and insect herbivores in wild rice agroecosystems.
Population regulation endures as a central issue in theoretical and applied ecology. The stabilizing forces that inhibit explosive population growth, and alternatively, the kinds of catastrophic loss that culminate in extinction are enigmatic. This study of spiders and insect herbivores in wild rice stands will evaluate the capacities of individual behavior and community interaction to regulate prey population densities. Arthropod populations were sampled at three natural (small lakes) and two cultivated wild rice agroecosystems in central Minnesota throughout the summer of 1997. Spider fauna differed spatially and temporally. Herbivory by the riceworm (Apamea apamiformis), the most important pest of wild rice, differed greatly among study sites. Objectives for 1998 are: 1) to monitor spider and insect populations throughout the wild rice growing season; 2) to quantify and explain disparate herbivore damage; 3) to study the ecology of major wild rice herbivores (e.g., oviposition choice and pupation behavior) and their natural enemies (with an emphasis on common spider species); and 4) to examine individual variation in spider feeding behavior. Research plans are presented and discussed. By taking advantage of the natural variation in predator behavior, adjusting cultivation practices to facilitate spider recolonization and persistence, and promoting species diversity, we may be able to implement long-term, stable control over insect pests.
Orr, M. A. and Uetz, G. W., Dept. of Biology, University of Cincinnati, Cincinnati, OH 45221-0006
Mate recognition in wolf spiders: do multiple modes prevent mistakes?
The wolf spiders Schizocosa ocreata and S. rovneri are ethospecies which use distinct multi-modal courtship behavior containing both visual and vibratory components. Cue isolation experiments suggest the relative roles of courtship communication modes have diverged in these species with the visual component appearing primary for S. ocreata and the vibratory component appearing primary forS. rovneri. Mate recognition errors increased when females were exposed to heterospecific males in only their secondary mode of communication. These data suggest that key elements vary in importance when presented separately. Interspecific hybrids, which can be produced in the lab, perform a courtship display containing key elements of both parental species. When females were presented with hybrids in cue isolation experiments, results varied. Female S. ocreata and S. rovneri were receptive to hybrids in 50% of the trials, when both primary and secondary cues were present. While S. ocreatafemales made an equal number of mistakes in visual (primary) and vibratory (secondary) modes, in S. rovneri less errors occurred when females were exposed to only visual (secondary) cues. This study suggests that there is potential for natural hybridization under conditions where one mode of communication is absent or constrained, and raises questions about the importance of multi-modal signaling.
Papke, M., Schulz, S., Institut fr Organische Chemie, Universitaet Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany, Prouvost, Olivierand Trabalon, M., Universite H. Poincar, Laboratoire de Biologie et Physiologie du Compartement, URA-CNRS 1293, B.P. 239, F-54506 Vandoeuvre-Les-Nancy, France
Chemical characterization of semiochemicals from the silk of Tegenaria atrica (Araneae, Agelenidae).
It is well known that spiders use semiochemicals for communication. Chemical stimuli can be used for mating and recognition of prey and enemies. In contrast to the vast number of chemically characterized semiochemicals from insects there are only a few allomones and even just two pheromones identified from spiders. The silk produced by the spider often plays an important role in the exchange of information. It is shown that males from Tegenaria atrica present different displays of courtship on webs of receptive females without the presence of a female spider. This behavior can also be released with a dichlormethane extract of the active silk in a bioassay. We analyzed dichlormethane extracts of the silk by gas chromatography and mass spektrometry and identified various compounds. Besides the predominate hydrocarbons and fatty acids some long-chain aliphatic alcohols and methylketones occur. More unusual are some long chain diols, monoglycerides, a hydroxyketone and a vinylketone which are also present on the silk. Structural verification was obtained by synthesis and chromatography. We are now testing a representative collection of identified chemicals in a bioassay, to show which compounds are able to release a change in behavior of males.
Parizi, M., Dept. of Zoology, University of Oklahoma in Norman. Norman, OK 73019, and Gaffin, D. D., Dept. of Zoology, University of Oklahoma in Norman, Norman, OK 73019
Investigation of spiking frequency of chemosensitive neurons in scorpion pectines in relation to photoperiod.
Pectines are large, comb-like appendages, located on the ventral body surfaces of all scorpions. The primary sensory structures on pectines are the numerous (105) pore-tipped structures, called peg sensilla, each of which is innervated by approximately 10-15 dendrites. Previous studies indicate that pectines are chemosensory and are important during mating encounters and perhaps in the chemical identification of food sources. Since scorpions are most active at night, we were interested in whether the spiking frequencies of peg sensilla are altered by photoperiod. Half of the test animals (Centruroides vittatus) were held under a mid-summer photoregime, half were held under a reversed photoregime. All other environmental factors were kept constant. For each animal, 3-5 minute extracellular recordings were obtained from approximately five peg sensilla on both right and left pectines. For each of the two treatment groups, half of the animals were recorded during their light cycle, the other half during their dark cycle. Under the conditions of our experiment, the normal and reverse photophase animals showed no significant difference in the firing frequency of peg sensilla neurons from that of normal and reverse scotophase animals. Subsequent data analysis suggests that there is variation in spiking frequency, which may be more specific than the resolution of our sampling window. Additionally we have found that spiking rhythms and frequencies of peg sensilla vary widely both within and between animals, indicating that peg sensilla may be heterogeneous in terms of their electrical activity.
Rakov S. Yu., Chair, Zoology of Invertebrates, Tomsk State University, Pr. Lenina 36, Tomsk, 634010, Russia
A zoogeographical account of the Salticidae in Middle Asia.
Middle Asia (MA), as we understand it, is the region usually attributed to the Sahara-Gobi subregion of Ancient Mediterranean of the Palaearctic Region. This territory is well known to be of high diversity with regard to both natural conditions and landscapes. According to the current calculations, the Middle Asian salticid fauna contains 191 species from 33 genera, that is ca. 25-30% of the entire spider fauna of the region at hand and ca. 4% of the world species diversity of the Salticidae. No monotypic genera are found in MA, with Yllenus, Chalcoscirtus,Pellenes and Proszynskiana being especially diverse in this region. The distributional patterns of all the salticids recorded in MA are analyzed. The bulk of the Middle Asian salticids turned out to be endemic species (56.0%); pointing to MA as one of the modern centers of species diversity of the Salticidae. European-Middle Asian and trans-Eurasian species are shown to be widespread over Middle Asia and number 10.4% and 7.3% correspondingly. Besides, the following zoogeographical salticid groups have been recognized: Caucasian-Middle-Asian (5.2%); Ancient Mediterranean and Turan-Mongolian (both 4.2%); Iran-Turanian (3.1%); and others (7.3 %).
Ramírez, M. J., Laboratory of Arthropods, Dept. of Biology, FCEyN, Universidad de Buenos Aires, Pabellón II Ciudad Universitaria (1428) Buenos Aires, Argentina, and Museo Argentino de Ciencias Naturales, Av. Angel Gallardo 470 (1405)
A cladistic generic revision of the spider subfamily Amaurobioidinae (Araneae, Anyphaenidae).
The phylogeny of the spider subfamily Amaurobioidinae is revisited, based on 80 representative species, selected to cover most of the morphological variation into the group. All available generotypes, and representatives of all so far recognized species groups were included and scored for 179 characters. Malenella nana(Malenellinae) and a vector with the states common to the Anyphaeninae, the remaining subfamilies of Anyphaenidae, were used to root the analysis. The data matrix analyzed with parsimony under implied weights produced 26 trees, differing only in relationships within Sanogasta, and in the placement of Ferrieria. Amaurobioidines arranged in two monophyletic tribes: Amaurobioidini, recognized by the grooved primary conductor and an apical loop on the spermatic duct, includes Amaurobioides, Axyracrus, Aysenia,Josa, Ferrieria, Acanthoceto and Coptoprepes. Gayennini, united by the presence of a median anterior hood in the epigynum and spherical spermathecae, includes Gayenna, Arachosia, Sanogasta,Philisca, Tomopisthes, Oxysoma, Tasata and Monapia.Liparotoma might be regarded as a subgenus under Philisca. Most genera should be redefined. Gayenna is confirmed to be monotypic, most previously included species should be assigned to Sanogasta. About one third of the included species are still undescribed. Five new genera should be created to place the species related with Gayenna strigosa, G. stellata, and several new species, all from central and southern Chile and Argentina. Aquatic habitat preferences seem to have evolved independently in Amaurobioides,Acanthoceto, and some Monapia species.
Reiskind, J., Dept. of Zoology, University of Florida. Gainesville, FL 32611
The origin of the spider fauna of peninsular Florida, a preliminary study.
Since most if not all the spider species on the Florida peninsula are relatively recent arrivals, either because the land had been fully submerged at some time during the Pleistocene or that the areas of the islands in the Florida "archipelago" during interglacial periods were small and local extinctions of the fauna were likely, an analysis of present day distributions permits determination of the likely sources of the spider fauna. Dispersal during the late Pleistocene played a dominant role in the origin of the peninsular Florida fauna. Climatic limits to present distributions offer additional clues to origins. Using explicit criteria most species can claim to be from one of four source regions: northern (far and near), western, southern (Caribbean), and autochthonous (species originating on the "islands" of the Florida "archipelago"). The vast majority of species come from the Some species are more difficult to place. "Neotropical" origin refers to species arriving either along the Gulf coast from Mexico or through the West Indies. Still others are considered cosmopolitan, some resulting from recent anthropogenic factors. The origins of species reflect the dispersal capabilities of the families to which they belong: the Theriididae showing predominantly southern and neotropical origins, while the Lycosidae having a large autochthonous component. More recently peninsular Florida itself may act as a source as well as a conduit for the dispersal of spiders.
Relys, V., Dept. of Zoology, Vilnius University, Ciurlionio str. 21/27, Vilnius, LT - 2009, Lithuania
Different patterns in phenology of alpine endemic and lowland spider species in the mountains (Eastern Alps).
During our investigations on epigeic spider communities in the eastern Alps (Gastein Valey, Salzburg, Austria) some interesting patterns in the phenology of alpine-endemic and lowland species have been noticed. Some of the typical lowland species may reach localities on different altitudes in the mountainous area and their life cycle is adopted to the environmental conditions occurring here. The lowland species reaches their maximum of occurrence at different time at different altitudes. The duration of this delay reflects differences between altitudes. It is well known for the species with one reproductive period in the year. Such patterns have been noticed in Alopecosa taeniata, Alopecosa pulverulenta, Pardosa amentata, Pardosa palustris, Xysticus cristatus. Another pattern of the phenology has been noticed in some alpine-endemic species. These species reach their maximum of occurrence at the same time at different altitudes. The differences in the altitudes causing delay by lowland species do not have importance for such alpine-endemic species as Robertus truncorum, Pardosa oerophila, Coelotes solitarius,Cybaeus tetricus, Lepthyphantes montanus and Centromerus pabulator.
Robertson, Marianne W.and Musser, Amanda, Dept. of Biology, Millikin University, Decatur, IL 62522
Survival of Hogna helluo(Araneae: Lycosidae) spiders raised as scavengers.
We examined whether a wolf spider, Hogna helluo, could be raised solely on dead prey. Control spiderlings (n = 78) were presented with live prey daily, and three experimental groups were presented with dead prey daily. One experimental group (n = 79) was given prey killed within one hour of distribution. Another group (n = 63) was given prey that had been dead for four days. The final experimental group (n = 63) was given prey that had been dead for seven days. We have successfully raised spiders in all four groups to maturity, demonstrating that H. helluo can survive as scavengers. This work is currently in progress but, at present, there is no significant difference in the number of days required to reach maturity or in the size of spiders presented with live versus dead prey.
Ruzicka, V., Institute of Entomology, Czech Academy of Sciences, Branisovska 31, CZ-370 05 Ceske‚ Budejovice, Czech Republic
Spiders in rocky habitats in central Bohemia.
Spiders of andezite and limestone rocks in central Bohemia were studied. The material was collected using hanging desk traps. Rocky habitats are inhabited by well established spider assemblages. Lesser slope angle and consequently more diverse terrain probably support higher species diversity. Some spider species inhabit exclusively rocky habitats. From material studied, Segestria bavarica C. L. Koch 1843, and Theridion betteni Wiehle 1960 occur in the Czech Republic exclusively on rocky habitats. Erigonoplus jarmilae (Miller 1943), Zelotes puritanus Chamberlin 1922 (= Zelotes kodaensisMiller & Buchar 1977), and Altella biuncata (Miller 1949) are considered to occur prevailingly in rocky habitats. Anyphaena furvaMiller 1967 is considered to live on tree trunks on sun-exposed rocks. Because of their specific warm microclimate, rocks can harbor isolated populations of thermophilous species in higher latitudes. The habitat tolerance of such species can be restricted only to rocky habitats under these conditions.
Santos, F. H. and Gnaspini, P., Departamento de Zoologia, Instituto de Biociencias, Universidade de São Paulo, Cx.P. 11461, 05422-970 São Paulo, Brazil
Seasonal comparative analysis of the locomotor activity of the cavernicolous harvestman Goniosoma spelaeum (Opiliones: Gonyleptidae).
Specimens of a single cave population of Goniosoma spelaeum (Mello-Leitão), a trogloxene harvestman, were followed for 60 days both during winter (June/July) and summer (December/January). Possible seasonal changes have been sought in the following variables: 1) distribution of specimens of different instars in the cave, 2) Percentile distribution of each instar within the population and proportion of males and females, 3) differences in weight during movements inwards and outwards the cave, 4) qualitative changes in diet; and 5) displacement and feeding behavior outside the cave. In general: 1) specimens concentrated in deeper regions of the cave during winter, 2) the number of marked harvestmen during the winter was significantly lower, especially considering adults which percentage reduced to its half, 3) proportion between male and female was altered from 1:1 in summer to 3:1 in winter, 4) adult and subadult body weight showed a detectable decrease during winter, whereas 4th and 5th nymphs presented no significant change, 5) food items were more diversified during the winter, 6) specimen displacement in the forest was preferentially vertical, and the "sit-and-wait" strategy was used to obtain food.
Savary, W., 813 Haight Avenue, Alameda, CA 94501
Observations on the phylogenetic affinities of Horribates Muma, with a descripition of the male of Horribates spinigerus Muma (Solifugae: Eremobatidae).
The relationships of the enigmatic solpugid genus Horribates Muma (Solifugae: Eremobatidae) are reevaluated in light of the discovery of the first known male of Horribates spinigerus Muma. The genus is currently placed in the subfamily Eremobatinae Roewer, which is defined by the synapomorphic presence of a single, distinctly flattened, triangular terminal claw on the tarsus of the first leg. The presence of paired terminal claws on the tarsus of the first leg in Horribates calls this placement into question. The chelicerae and flagellum complex of the male of H. spinigerus resemble those of Eremochelis flexacus Muma and offer new clues to the relationships of the genus.
Searcy, L. E. and Rypstra, A. L., Dept. of Zoology, Miami University Oxford, OH 45056
Air-born chemical communication in Pardosa milvina (Araneae, Lycosidae).
Adult males of the wolf spider species Pardosa milvina (Araneae, Lycosidae) were examined for detection of air-born chemicals. We hypothesized that P. milvina use these pheromones as a means of sexual communication among conspecifics. Using a two choice olfactometer, we tested the response of adult male P. milvina to a number of potential stimuli. Adult virgin female P. milvina elicited an attractive response from the male, thus supporting our hypothesis. Other stimuli included immature P. milvina, one male P. milvina,and two males together. In all of these cases, males showed no attractive response to the stimuli. In all trials visual and vibratory stimuli were controlled for. The second set of experiments were run using pitfall traps baited with adult virgin female P. milvina as attractant. Visual and vibratory cues were controlled for, and again male adult P. milvinashowed an attractive response to females that was significantly different than the control results.
Segev, O., Ben-Gurion University of the Negev, Mitrani Center for Desert Ecology, Sede Boqer, 84990, Israel
Sperm competition and male mating strategies in the widow spider, Latrodectus revivensis.
Competition among males is a major force driving sexual selection. Male-male competition occurs at different morphological, behavioral and physiological levels. The pattern of sperm precedence will determine whether pre- or post-copulatory mate-guarding is advantageous for males. Thus, the value of a female to the male should change with female state, reproductive history and age in accordance with the sperm priority pattern. I tested the hypothesis that in the widow spider Latrodectus revivensis the dominant pattern is first-male sperm priority and consequently adult males compete over virgin females. During the spring and summer of 1996 and 1997 in a natural population of spiders in the central Negev, I recorded a decrease in adult male size and an increase in adult female size during each season. The maximum number of males per female nest was observed when females molted to maturity, but the same males cohabited with females even 60-70 days following female maturation. The maximum number of adult males was recorded when half of the females in the population were adult and half were still sub-adult. Males tended to cohabit longer with sub-adult females than with adult females. Using two reciprocal copulation sequences of normal and sterile (g-radiated) males, I found a 70% priority of first-male sperm in the first egg sac, which decreased and was even reversed in subsequent sacs. These results and observations suggests cohabitation with already-mated females may be an alternative strategy for late-maturing small males, in comparison with pre-copulatory cohabitation for large, early-maturing males of Latrodectus revivensis.
Shillington, Cara, Dept. of Zoology, Oklahoma State Univ., Stillwater, OK 74078 and McEwen, Brian, Dept. of Anatomy, Pathology and Pharmacology, College of Veterinary Medicine, Oklahoma State Univ., Stillwater, OK 74078
Post-maturity molt in a male tarantula Grammastola spatulata (Araneae: Theraphosidae): a partially successful event.
This is the first documented observation of a post-maturity molt in a male tarantula (Grammastola spatulata). Additional anecdotal evidence suggests that such events, although rare, do occur among certain species of tarantulas. To date, post-maturity molts have been noted only in three South American species: Grammastola spatulata, G. rosea and Paraphysa sp. It appears that some males are unable to extract themselves successfully from the shed cuticle resulting in loss of appendages and death. The authors have observed only one maleG. spatulata survive a post-maturity molt. Although still alive seven months after the molt, the male is missing both his palpal organs which are essential for sperm storage and copulation and only has four legs. In addition, the tibial spurs are a different size and shape. The feasibility of a post-maturity molt in male tarantulas is uncertain because they may no longer be able to mate.
Smith, D. R., Dept. of Entomology, University of Kansas, Lawrence, KS 66045
Genetic markers for the study of social spiders.
Earlier allozyme studies of cooperative social spiders have revealed an unusual population structure: high levels of genetic similarity within colonies and high levels of genetic differentiation among colonies. The cooperative social spiders that have been studied have relatively few polymorphic enzyme loci, with few detectable alleles. However more detailed study of population structure, dispersal and colony foundation in cooperative spiders has been hampered by a the paucity of genetic markers available. Both microsatellites and amplified fragment length polymorphisms (AFLPs) typically reveal much more genetic variation than allozymes. This study compares genetic variation revealed by AFLPs in cooperative social species (Anelosimus eximius, Theridiidae; Stegodyphus sarasinorum and S. dumicola, Eresidae) and solitary congeners (A. studiosus, S. lineatus).
Snyder, W. E. and Wise, D. H., Dept. of Entomology, University of Kentucky, Lexington, KY 40546
Multiple trophic cascades caused by individual and combined impacts of generalist predators.
We examined the multi-trophic impact of two common generalist predators, carabid beetles and lycosid spiders. We manipulated immigration of carabids and lycosids by intercepting them as they colonized vegetable gardens. Carabids, lycosids, both, or neither predator were then released into the gardens, establishing a complete 2 X 2 factorial design. Carabid and lycosid immigration was manipulated daily through a spring garden of cucumber and then a summer garden of squash. Open plots, where carabid and lycosid immigration was not manipulated, were included as a reference treatment. In the spring gardens, both carabids and lycosids reduced densities of striped cucumber beetles, an important herbivore. The impact of lycosids was strong enough to increase fruit production ca. 25%. In the summer gardens, carabids reduced squash bugs, which replace cucumber beetles as the dominant herbivore, leading to a ca. 33% increase in squash yield. Lycosids had the opposite effect - squash bug densities were significantly higher in lycosid-immigration plots, leading to a ca. 33% reduction in squash yield. Lycosids apparently increased squash bug densities by preying upon minute pirate bugs and perhaps also nabid bugs, which eat squash bug eggs. Thus later in the season lycosids caused a 4-level trophic cascade that substantially reduced vegetable production. The relative strength of direct and indirect effects determined the net impact of these predators on plant productivity.
Souza, C., DIAP-C, Instituto Vital Brazil, P. O. Box 100.028, 24230-340, Niterói, RJ, Brazil, Monnerat, A. T., DBBM, Soares, M. J., DUBC, Fiocruz, P.O. Box 926, 21045-900, Rio de Janeiro, RJ, Brazil, França, C. V., DIAP-C, Instituto Vital Brazil P. O. Box 100.028, 24230-340, Niterói, RJ, Brazil, and Souza, W. M., 1DIAP-C, Instituto Vital Brazil, P. O. Box 100.028, 24230-340, Niterói, RJ, Brazil
An overview on black widows in Brazil.
The lack of basic research on biology, systematics, epidemiology, composition and action of venom of Black Widows from Brazil has led to underestimated, incomplete knowledge about these spiders. We discuss the biological relationship between two populations of Latrodectus curacaviensis, one from the northeast states, responsible for the majority of human latrodectism reported early to the public health system and another, found in the southeast area of the country. Biometric measurements of legs and carapace of males (n=27) and females (n=40) from each population show very significant differences (P<0.05) in size of the spiders. The variation in the morphology of females genitalia from both populations is analyzed by electron scanning microscopy and field observations on reproduction, distribution, feeding, webs, seasonal occurrence are also discussed. Preliminary results of in vivo toxicity analysis of the venom from Brazilian Latrodectus geometricus and clinical observations of human envenoming due to these spiders support our belief on severity of the intoxication induced by them. The high level of protective action presented by a hyperimmune antilatrodectus antivenom developed by Instituto Vital Brazil and tested against the main toxic effects induced by Latrodectus curacaviensis venom shows the potential contribution of this new tool in the management of human envenoming by Black Widow spiders bites in our country.
Stocks, I. C., Dept. of Biology, Western Carolina University, Cullowhee NC 28723
Genitalic homologies in the agelenid genera Agelenopsis and Barronopsis and putative synapomorphies of Barronopsis.
As a first step in revising the systematics of the spider genus of the spider genus Barronopsis (Agelenidae), I present detailed drawings of male and female genitalia which illustrate a number of potentially informative character states. Illustrations of the variation in female genital morphology found amongst morphospecies are presented for the first time. Additionally, putative homologies in genital structures of Barronopsis, its sister genus Agelenopsis and those of other agelenine genera are presented. I revise the genital terminology of Gering (1953) and others, which was based largely on function, by applying the homology-based terminology of Sierwald (1990), Coddington (1990) and others.
Szita, E., Eotvos Lorand University of Sciences. Budapest, Hungary, and Samu, F., Plant Protection Institute of the Hungarian Academy of Sciences. PO. Box 102,H-1525 Budapest, Hungary
Taxonomic review of the spider genus Thanatus (Philodromidae, Araneae) of Hungary.
The spider genus Thanatusis one of the most complicated groups of the family Philodromidae. All of them are epigeic animals. The following six species of the genus can be found in Hungary: T. arenarius Thorell, 1872, T. atratus Simon, 1875, T. formicinus (Clerck, 1757), T. pictus L. Koch, 1881, T. sabulosus(Menge, 1875), T. striatus C. L. Koch, 1845. The occurrence of two further species (T. coloradensis Keyserling, 1880, T. vulgarisSimon, 1870) is not proved, but they might occur in Hungary, so they are also included in the present study. Description, illustrations and distributional maps for each species are provided. The examination is based on the collections of the Natural History Museum of Hungary, Budapest, as well several museums and arachnologists from Hungary and Europe, and our own collections. Th. atratuswas one of the subspecies of T. vulgaris until 1983, when it was raised to the level of independent species. After the examination of all specimens available to us, it seems that probably only T. atratus occurs in Hungary. Apolophanes babaly Logunov, 1996, is a junior synonym.
Tanasevitch, A. V., All-Russian Institute on Nature Conservation, 113628 P.O. VILAR, Moscow, Russia
The linyphiid spiders of the Himalaya: composition, chorology, faunogenesis (Aranei, Linyphiidae).
At present, about 130 species of linyphiid spiders have been registered in the Himalaya. Nepal is certainly the area best explored in this respect (78 species), followed by Karakorum (30 species) and Kashmir (8 species). A check-list of the Himalayan linyphiids is presented, with species distributions between subregions and altitudinal belts. Species from the "Lepthyphantes" complex and from the genus OedothoraxBertkau appear dominant, amounting to 40% of the regional fauna. Taxonomic and chorological analyses are proposed as well as zoogeographical relations and presumed origins of the Himalayan linyphiid fauna.
Tsurusaki, N., Dept. of Biol., Fac. of Educ., Tottori Univ., Tottori, 680-8551 Japan; Ueshima, R., Dept. of Biol. Sci., Grad. School of Sci., Univ. of Tokyo, Tokyo, 113-0033 Japan, and Gorlov, I. P., Dept. of Biol., Fac. of Educ., Tottori Univ., Japan and Inst. Cytol. and Genet., Siberian Branch of Russian Acad. of Sci., Novosibirsk, Russia
Geographical differentiation of karyotypes in the Nelima genufusca group (Opiliones) and analyses of chromosomal hybrid zones in Nelima nigricoxa.
The Nelima genufuscagroup (Phalangiidae: Leiobuninae) is a closely-related group of harvestmen widely distributed in Japan and consists of two described [N. nigricoxaSato & Suzuki and N. genufusca (Karsch)] and one (or more) undescribed species. The group shows extensive geographical diversity in chromosome number with ranges: 2n=16-22 in N. nigricoxa and 2n=18-22 in N. genufusca. In each species chromosomal hybrid zones were found. Of these, we analyzed two hybrid zones (2n=20/18a and 18a/16) of N. nigricoxa in detail. The zones are located in the area around Mt. Daisen and Mt. Hiruzen, Tottori, western Japan. The width of the 20/18a zone is approximately 0.5-3km and that of 18a/16 zone ca. 3km. In both zones, frequency of heterozygous karyotypes was significantly lower than the expected from the Hardy-Weinberg equilibria. No degeneration of spermatogenesis in heterozygous males (2n=19) was observed in the 20/18a hybrid zone surveyed. Analysis of meiosis in the heterozygotes showed low (about 2-3%) malsegregation rate. Mean dispersal distance estimated by preliminary survey with a mark-recapture technique was 29m (SD=20.3). Using simple diffusion model we calculated that minimal age for 0.5 km zone is a little more than 200 years and that for 3km zone is about 7,700 years. The estimations roughly agree with the volcanic history of the area. A phylogeny within the genufusca group depicted by using sequence data of ca. 1kbp DNA fragments of a mitochondrial gene (COI: cytochrome oxidase I) demonstrated those chromosome races have arisen without a profound genetic differentiation.
vander Tuuk, C. and Pascoe, F., Dept. of Natural Sciences, University of St. Francis, Joliet, IL 60435
A comparative study of spider and insect metabolic rates.
Anderson (1970, 1994, 1996), and others have examined the metabolic rate of spiders and proposed that spiders have an adaptation for lowering resting metabolic rate during starvation. Markezich's (1987) results indicated that these lowered rates are a result of starvation rather than an innate adaptive mechanism for surviving periods of low prey availability. Wise (1993) suggested that the question may be best answered by comparing the resting metabolic rate of spiders with other predaceous arthropods. Therefore, we have compared the resting metabolic rate of fed and starved spiders and insects with similar predatory habits. Specifically salticid, sparassid and thomisid spiders were compared to phymatid (Hemiptera) and cicindellid (Coleoptera) insects. All of these arthropods are found in similar habitats and hunt insect prey with similar strategies. Each arthropod was placed into a 250 ml Schott bottle and oxygen consumption/C02 production was measured using a Columbus Instruments OxyMax respirometer. Our results showed that the spiders: 1) lived longer without food than the insects, 2) had a significantly lower average metabolism over the entire five day experimental period, and 3) did not vary their metabolic rate over the five day time period. These results suggest that the spiders do have a unique metabolic adaptation which allows them to survive periods of low prey availability.
Volschenk, E. S., School of Environmental Biology, Curtin University of Technology, GPO Box U 1987, Perth, W.A. 6845, Australia, and Harvey, M. S., Dept. of Terrestrial Invertebrates, Western Australian Museum, Francis Street, Perth, W.A. 6000, Australia
Preliminary systematic studies of Lychas-like scorpions (Scorpiones: Buthidae) in Australia.
Scorpions of the genus Lychas(Buthidae) are common throughout Australasia. The first major treatment of the Australian species by Glauert (1925) recognized as many as 16 species, but the most recent taxonomic treatment of the Australian scorpions (Koch 1977) reduced this number to three - each of which were deemed to be polymorphic. Recently, Kovarik (1997) in a revision of the genus which concentrated on the non-Australian fauna, transferred one of these Australian species, L. alexandrinus, to the genus Hemilychas, reinstated Lychas mjobergiand described L. buchari. The research currently being conducted indicates that the Australian Lychas fauna consists of at least 25 species and that, judging from all available evidence, these species are endemic. Lychas also has an extremely interesting distribution, as it is the most naturally widespread buthid (data presented by Kovarik 1997a, 1997b). Koch (1972) hypothesized the derivation of Australian buthids as from New Guinea and Indo-Pacific Islands, following the development of Pleistocene land bridges with Australia. However, evidence deduced from the present study indicate a very different origin. The phylogenies presented here show that the Australian Lychas-like buthids (Lychas, Hemilychas, Australobuthusand Isometroides) represent a monophyletic clade, and that this group may have Gondwanan origins.
Wagner, James D., Biology Program, Transylvania University, 300 North Broadway, Lexington, KY. 40508, Toft, Soeren, Dept. of Zoology, University of Aarhus, Bldg. 135 DK-8000 Aarhus C, Denmark, Erny, Keith, Dept. of Entomology, University of Kentucky, Lexington, KY 40546, and Wise, David H., Dept. of Entomology, University of Kentucky, Lexington, KY 40546
Diversity of the forest-floor spider community: the role of spatial and temporal stratification.
Since most spiders are size-selective generalist predators who can act as both intraspecific competitors and intraguild predators, it is remarkable that they exhibit such a high diversity and numerical abundance within the leaf litter of the forest floor ( ~18 families and 95 genera). Ecologists have proposed two potential factors that may contribute to the observed species richness: (1) diversification in spider foraging mode (web building versus active pursuit), and (2) species-specific microhabitat segregation (temporal or spatial separation). We studied the leaf-litter spider community from an oak-hickory-maple forest in Berea, KY (Madison Co.) to determine if foraging guilds and dominant spider genera are randomly distributed within the leaf litter. Using both specially designed pitfall traps that sampled at three different litter depths and a modified quadrat sampling technique we surveyed the leaf-litter spider community from April 1995 to October 1995. Over 3200 spiders were collected representing 18 families. Spiders exhibited non-random spatial and temporal distribution within the leaf litter. Web-building spiders were found significantly deeper in the litter than cursorial spiders. Correspondence analysis revealed three distinct spatial-temporal correspondence clusters of spider families: (1) Lycosidae with Salticidae and Ctenidae, (2) Thomisidae with Gnaphosidae, and (3) Araneidae with Linyphiidae and Dictynidae. These patterns suggest that segregation by litter depth may help to explain the rich species diversity within the forest-floor spider community.
Waldock, Julianne, M., Western Australian Museum, Dept. of Terrestrial Invertebrates, Francis St., Perth, WA 6000, Australia
No abstract submitted.
Wang, X. P., Dept. of Entomology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024
A revision of the genus Tamgrinia(Araneae, Amaurobiidae).
The spider genus Tamgriniacurrently includes three species from western China and the East Sikkim region of India: T. alveolifer (Schenkel, 1936), T. laticeps (Schenkel, 1936), and T. chhanguensis (Tikeder, 1970). In this paper, two more species are recognized: T. coelotiformis (Schenkel, 1963), which is removed from the synonymy of T. laticeps, and T. tulugouensis sp. n. The species Amaurobius potanini Schenkel, 1963 is newly synonymized with T. laticeps rather than with T. alveolifer. Both males and females of T. laticeps are described. The original female of T. laticeps described by Schenkel in 1963 is shown to be a coelotine species: Paracoelotes spinivulva (Simon, 1880). The tracheal morphology of the genus Tamgriniais also presented for the first time.
Ward, M. A., Ecology Section, Institute of Natural Resources, Massey University, Palmerston North, New Zealand.
Conserving New Zealand's endemic spider Latrodectus katipo.
The conservation status of New Zealand's coastal spider, Latrodectus katipo, is undetermined. These results deem it a "Category A" species: 'Highest Priority Threatened Species', along the west coast of the lower North Island. Speculation of a decline led to the establishment of five preliminary 3m x 3m quadrants at selective sites to determine L. katipo distribution, understand habitat use, and determine potential threats to their population viability. The eleven previously inhabited locations were surveyed as were ten additional sites. Reproduction is apparent but the location of only forty-seven L. katipoand thirty-one egg-sacs over the 2.5 month period supports a population decline. Distribution was predominantly inconsistent along the coast. All L. katipo were located at seven of the twenty-one sites. Individuals were uncharacteristically grouped and each group displayed a gender bias. Land modification, mistaken identity of Steatoda capensis as L. katipo, and L. katipo populations being overlooked, factor in the apparent decline. S. capensis was present at six of the seven L. katiposites and ten of the fourteen other sites. L. katipo appears to have declined and/or disappeared from areas where S. capensis appears to be increasing. This suggests the highly adaptable S. capensis is competitively displacing L. katipo in modified habitats. Preliminary temperature and humidity measurements suggest L. katipo may lower web-humidity and raise web-temperature in relation to ambient conditions.
Weldon, D., Slotow, R., Adams, N., Biology Dept., University of Natal, Private Bag X10, Dalbridge, Durban 4041, South Africa and Crouch, T., Durban Natural Science Museum, P.O. Box 4085, Durban 4000, South Africa
Thermoregulatory advantage of large nest size of social spiders Stegodyphus spp. (Araneae: Eresidae).
Social spiders, Stegodyphus mimosarum, build large, compact nests from which one or more capture webs extend. Colonies of one to several hundred build refuge nests with the longest central axis ranging in size from 2cm3 to 30cm3 or greater. During the day, nest core temperature is normally 2°C or 3°C higher than ambient temperature. If the nests behave as a solid object, individuals may gain from the thermal benefits associated with increased nest size. Larger nests will cool more slowly, thus allowing spiders to remain active for longer at low ambient temperatures. Cooling and heating curves were measured for large and small nests in the laboratory and field. Under laboratory conditions, large nests had significantly shallower cooling and heating curves than small nests. However, under field conditions, nest size did not have a significant effect on the cooling curves. Possible explanations for this inconsistency include small sample size, and poor experiment design such as the height of the nest above the ground. An analysis of the difference between nest core and ambient temperatures was done on various nests in Weenen Game Reserve around midday. The nest height above the ground was found to have a significant influence (p= 0.0008), with temperature difference increasing with decreasing height above the ground. The nests below 2.63 m generally had a greater temperature difference. While size alone did not have a significant effect, the combination of size and height in determining the temperature difference did (p= 0.0091). Therefore, while under controlled conditions nest size affects an individual's microclimate, under field conditions, this advantage is less consistent.
Xavier, E., Dept. of Biology, University of Feira de Santana, BA, Brazil, 44.100-000, and Rocha, P. L. B., Dept. of Zoology, Federal University of Bahia, BA, Brazil, 40.170-110
Microhabitat use by an assemblage of cursorial arachnids in sand dunes from Brazilian semiarid Caatinga.
Cursorial arachnids from Ibiraba sand dunes (Bahia) were investigated for seasonal patterns of microhabitat use and partitioning. Arthropod sampling was performed during dry and wet seasons using pitfall traps. Microhabitat in each trap was recorded as 7 variables including topography, vegetation covering, and litter amount. Microhabitat electivities were calculated based on resource availability, and the patterns of partitioning were checked based on multiple comparison tests. PCA on microhabitat variables allowed identification of underlying factors. The 5 most frequent species correspond to 85% of all arachnids collected (N= 2197, Acari excluded): spiders Leprolochus sp. n.-1 (47.1% - Zodariidae), Xenoctenussp. n. (20% - Zoridae), Leprolochus sp. n.-2 (12.5%),Sicarius tropicus(1.8% - Sicariidae), and the solpugid Mummucia sp. n. (5,0% - Mummucidae). Xenoctenus did not show electivities on the analyzed variables. It was detected electivity on Leprolochus sp. n.-1 for shadowed areas and Leprolochus sp. n.-2 for areas covered by the terrestrial bromeliad Bromelia antiacantha. During the dry season both Leprolochusspecies and the solpugid have avoided exposed areas (dune summits and areas covered only by heliophylic sub shrubs), but Leprolochus sp. n.-2 preferred areas covered by litter and Mumucia preferred Bromelia-covered areas. Unexpectedly, Sicarius avoided exposed areas only during wet season. Partition analyses based on proportions performed worse than those based on electivities, although they have detected partition between the species of Leprolochus in the dry season based on amount of litter and between Sicarius and Xenoctenus in the wet season based on shadowed areas.
Yan, Hengmei and Liu, Manyuan, Dept. of Biology, Hunan Normal University, Changsha, 410081, China, and Kim, Joo-pil, Dept. of Applied Biology, College of Life Resource Science, Dongguk University, 26, 3-ga, Pil-dong, Chung-gu, Seoul, 100-715, Korea
Predation efficiency of the spider Tetragnatha squamata (Araneae: Tetragnathidae) on tea leafhopper Empoasca vitis.
Laboratory experiments (T. 25 ± 1°C, R. H. 75%) demonstrated that the spider Tetragnatha squamata shows a functional response to increasing numbers of its prey: tea leafhopper Empoasca vitis, which can be described by using Holling's disc equation: Na = 0.5964N/(1+0.008356N), A + 10.7948P-1.00105 and the predation rate was E = 0.5986Q-0.6891.
Yan, Hengmei, Yin, Changmin, Wang, Hongquan, Lu, Lan and Tang Guo, Dept. of Biology, Hunan Normal University, ChangSha 410081, China
Bionomy of the theraphosid Selenocosmia huwena (Araneae : Theraphosidae) from China.
The theraphosid Selenocomia huwena was identified as a new species of family Theraphasidae in 1993. It occurs in tropical areas of southern China. Selenocosmia huwena has a body length of 6-9cm, and measures 9-12cm with the legs extended. This is the largest spider in China. It lives in burrows. Rarely do they live in regions of dense forest or heavy undergrowth, preferring open areas on hillsides or the fringe of cultivated lands. The burrow usually has a loose webbing tube at the entrance. The construction of burrow is horizontal or at a slight angle. Under laboratory conditions mated female spiders laid white egg sacs in the middle of July, with average weight of egg sac 10.709±4.1g (n=15), the length of eggs sac 4.73±0.6cm and breadth 4.23±0.6cm.The number of eggs per the egg sac varied from 42 to 213, with an average of 131.5. During the incubation period, the female spider protected her sac and generally did not take food until the 2ndinstar spiderlings emerged from the sac. Incubation of eggs lasted about 30 days. After emergence, the 2nd instar spiderlings remained in the burrow for 3 to 5 days without adelphophagie behavior. When the 2ndinstar spiderlings became the 3rd instar ones, the spiderlings dispersed. A correlation was found between the weight and length of the spider and the weight of its ovary. The regression equation between the weight of the spider and its ovary was Y=-15.1414+2.8024X, r=0.9123 (Y means weight of ovary; X means weight of spider).The regression equation between the length of the spider and the weight of its ovary was Y=-51.6429+1.9262X, r=0.8656 (Y means weight of ovary; X means length of spider). Temperature had a great effect on spider activity and development and decreased with low temperature. The appropriate temperature scale for spider activity and development ranged between 20°C and 30°C.
Zhu, Mingshing andSong, Daxiang, Dept. of Biology, Hebei Normal University, 050016, Shijiazhuang, China, and Kim, Joo-pil, Dept. of Applied Biology, College of Life Resource Science, Dongguk University, 26, 3-ga, Pil-dong, Chung-gu, Seoul, 100-715, KoreaTwo species of spiders of the genus Trachelas (Araneae: Corinnidae) from China.
The present paper deals with two species of spiders of the genus Trachelas L. Koch, 1866 from China. A key to four Chinese species of the genus Trachelas is given.
Ziv, M., Lubin, Y., Mitrani Center for Desert Ecology, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Israel
Ecological observations of Cyrtophora citricola colonies in an extreme desert habitat.
The araneid spider Cyrtophora citricola lives in colonies in tropical Africa and the Mediterranean basin. In Israel, low-density desert populations of this species are recorded at a few sites along the Syrio-African rift valley. In the Arava valley at 100m elevation, C. citricola build their webs only on the south-east sides of Acacia trees. A few individuals were found on nearby Anabasis and Hamada shrubs. For three colonies of C. citricola temperature, wind speed, and insect availability were examined. Temperature and insect availability did not different significantly on four sides of the trees. Wind speed from the north-west (mean=3.7m/s) was significantly higher than wind from south-east (mean=2.2m/s, p<0.05), suggesting that the location of the colonies on the trees may be related to the wind regime in the area. The webs are built in close proximity to one another and are found both on the outer branches of the tree as well as on inner branches. The tent-shaped orb webs form a three-dimensional colony. Although a correlation exists between the size of the spider and web size (r=0.8), there were no differences in sizes of spiders or webs found on inner and outer branches of the tree. Similarly, prey capture rates were not different in webs located on the inner and outer parts of the tree. Although individuals living on trees were significantly larger (body length, mean=3.9mm) than those living on shrubs (mean=2.2mm), no difference was detected in prey capture rates, which were low in both locations. Hourly observations of behavior indicated that prey capture occurs mainly during the day while web construction occurs at night.