Abstracts

Arranged Alphabetically
by First Author 

2002 Annual Meeting

The American
Arachnological Society

(Most recent entry: 6 / 10 / 2002)

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A through C

A Phylogenetic View of Sociality in Cobweb Spiders (Theridiidae)
 Author: Ingi Agnarsson  Institutions: George Washington University and Smithsonian Institute
 Abstract: Spiders are a lineage of predominantly aggressive and distinctly territorial hermits. Tolerance is usually limited to conspecifics, briefly during mating, or as tiny juveniles emerging from the egg sac. Yet, a few species do share webs, and about 20 do so permanently (quasi-sociality). While about half of these are phylogenetically widespread and isolated, the remainder are cobweb spiders. As the family represents less than 6% of spider diversity, the concentration of social species there seems to require an explanation. In order to examine the phylogenetic patterns of sociality within the family I present a cladistic reconstruction of theridiid relationships, based on morphological data. The results indicate that; first, the relatively high number of social theridiids is a result of multiple (four) origins of sociality, rather than a diversification within a single social lineage. Thus, as in other spiders, social clades never are specious; spider sociality seems to represent a diversification dead end, rather than a key innovation. Second, I found that within Theridiidae, social origins are non-randomly clustered within a distal lineage. Presumably that lineage exhibits traits that facilitate social evolution. The "maternal care route" hypothesis, suggests that web-sharing sociality is merely an extension of maternal care, whose prolongation may be more likely where certain other traits, e.g. three- dimensional webs are present. Congruent with such ideas, I found that sociality in cobweb spiders is indeed concentrated in a lineage where maternal care occurs in the presence of three-dimensional webs. (Added 5 / 28 / 2002)

Spiders in elementary schools
 Author: Bill Bennett  Institution: Crosbyton County Memorial Museum, TX
 Abstract: Scream and squash is the usual reaction of kids, a behavior learned from parents, when encountering a spider. That is until they have been properly enlightened by a biologically hip teacher (rare and endangered) or a by a courageous AAS volunteer. These knee-biters learn to distinguish between all the good species from the few really dangerous ones. They also learn what distinguishes the arachnids from other arthropods, their varied predatory techniques and their important place in the environment. Halloween offers a great opportunity for spider education as well as Native American studies, e. g., legends of the Spider Grandmother in Kiowa lore, Spider Woman of the Cherokees, etc. You will find that 1st through 4th graders are easier to teach than graduate students! (Added 6 / 1 / 2002)

The evolutionary origin of sphingomyelinase D in Loxosceles venoms: how, when and why?
 Author: Greta Binford  Institution: University of Arizona
 Abstract: Sphingomyelinase D (SMD) in Loxosceles venoms is a sufficient causative agent for lesion formation and is only known elsewhere in a few species of pathogenic bacteria. This makes the evolution of SMD an interesting puzzle. I will discuss insights into the evolution of Loxosceles SMD based on characteristics of the gene and comparative biochemical assays. The gene spans at least 6,500 bp, contains 5 introns, and is a member of a multigene family. A signal sequence indicates SMD is expressed as a zymogen with a trypsin cleavage activation site. Weak amino acid sequence similarity suggests SMD is a divergent member of the broadly conserved glycerophosphoryl diester phosphodiesterase family (GDPD). These data strongly suggest that spider SMD has been evolving within a eukaryotic genome for a long time ruling out evolutionary origin by recent horizontal transfer from bacteria. Comparative enzyme assays indicate that SMD originated in the ancestors of Loxosceles and Sicarius making it likely that the enzyme is present in all members of this clade. Venoms of spiders in the Loxosceles/Sicarius clade (with SMD) are more potent when injected into Manduca sexta than are venoms of Drymusa, a close relative without SMD in their venom. This is suggestive that the enzymatic activity of SMD (present in large quantities in the venom) may contribute to prey paralysis. (Added 5 / 16 / 2002)

Behavioral diversification in the adaptive radiation of Hawaiian orb-weaving Tetragnatha
 Authors: Todd Blackledge and Rosemary Gillespie  Institution: University of California, Berkeley
 Abstract: The extreme isolation and habitat heterogeneity of the Hawaiian Islands has contributed to many spectacular evolutionary radiations of organisms, exemplified within spiders by the orb-weaving Tetragnatha (Araneae: Tetragnathidae). While the "spiny leg" lineage of Tetragnatha has abandoned the use of webs in prey capture, most endemic Tetragnatha (approximately 50 species) still construct orb webs. This web-building clade may have speciated across the archipelago more rapidly than the spiny leg clade, suggesting that construction of webs has facilitated species coexistence or even diversification itself by allowing finer subdivision of microhabitat or prey resources within habitats. Here, I show that sympatric species of Hawaiian Tetragnatha display distinct differences in the microhabitats and architectures of their webs, as well as the prey that they capture. I examine the possibility that web architecture and location reflect adaptation to local selective pressures and that similarities in selective pressures between habitats on different islands have led to convergent evolution of community structure. (Added 5 / 7 / 2002)
Neotropical jumping spiders of the genera Sidusa and Cobanus, with discussion of phylogenetic relationships within the Euophryinae (Araneae: Salticidae)
 Author: Gitanjali S. Bodner  Institution: University of Arizona
 Abstract: Members of the jumping spider genera Cobanus F. O. Pickard-Cambridge 1901 and Sidusa Peckham and Peckham 1896 are amongst the most abundant and conspicuous spiders in many Neotropical rainforests, yet distinguishing features have not been proposed for either genus, and neither has previously been revised. Similarly, the euophryine subfamily is one of the dominant salticid groups throughout the world, yet very little work has been done on its boundaries and internal phylogenetic structure. This work suggests synapomorphies for Cobanus and Sidusa, and addition of newly discovered species approximately doubles the size of both genera. Twenty-four species are newly described here, twelve re-described, three synonymized, two transferred to other genera, and several recognized as being misplaced. Phylogenetic analysis of morphological characters in these species and representatives of thirty other euophryine genera supports the sister relationship and mutual monophyly of Cobanus and Sidusa, provides insight into character variation within the subfamily Euophryinae, and suggests the existence of several previously unrecognized euophryine clades. (Added 6 / 4 / 2002)

Identification of Chitin in the Extracellular Matrix of the Duct Region of the Ampullate Glands of Latrodectus hesperus
 Authors: Teresa Bonomini, Jason Newmark,
Laurie ONeil and Merri Lynn Casem
 Institution: California State University, Fullerton
 Abstract: The purpose of this study was to examine the structure and composition of the major and minor ampullate glands in the Black Widow Spider (Latrodectus hesperus); specifically, the duct region. We hypothesized that the duct did not contain chitin. The presence of chitin was determined using calcofluor, a chitin-specific dye. Findings were not consistent with our hypothesis; fluorescent microscopy revealed the presence of chitin in the duct region of 80% of the specimens analyzed. (Added 5 / 16 / 2002)

Title: Molecular comparisons of scorpion species groups from the Genus Vaejovis (Family Vaejovidae) using a 500 base-pair sequence of mitochondrial 16S rDNA
 Authors: Karen Bost, Richard Henson, Mary Connell, and Zack Murrell Institution:Appalachian State University
 Abstract: The genus Vaejovis has the largest distribution and degree of variation of any scorpion genus found in the United States. Due to a lack of distinct morphological characteristics, the phylogeny of this genus is poorly understood. Species of this genus have been separated into five loosely defined groups based on morphological and ecological characteristics. The five species groups include eusthenura, intrepidus, mexicanus, nitidulus, and punctipalpi. Representative species and populations from each group except intrepidus were examined using a 500 base-pair sequence of mitochondrial 16S rDNA in order to assess phylogenetic relationships. The intrepidus group was not analyzed due to the inability to obtain specimens. Scorpions were obtained at night using ultraviolet light in Big Bend National Park and Guadalupe Mountains National Park Texas, throughout Utah, Arizona, New Mexico, North Carolina, Tennessee and Mexico. Habitats ranged from consolidated sand to rocky substrate. Sequences were compared to Hadrurus arizonensis , a member of a related Family (Iuridae). Preliminary data consisting of twenty-eight sequences from the four representative groups and outgroup were analyzed using PAUP where a heuristic search was performed to create a consensus tree computed by fifty percent majority rule. Early evidence suggests a combined monophyletic origin of the mexicanus and the nitidulus groups. The eusthenura and punctipalpi groups have not been resolved at this time. (Added 4 / 26 / 2002)

Gum-Foot Threads: Prey Capture by Spring-Action in Black Widow Webs
 Authors: Crystal Botham, Yurixsa López and Anne Moore  Institution: University of the Pacific
 Abstract: Vertical gumfoot threads in a black widow's (Latrodectus hesperus) cobweb catch ground-moving prey by sticking to the prey, detaching from the ground and raising the prey into the air. We propose that gumfoot threads, unlike other spider silks, act as a spring, using stored energy from pre-stretching of the threads to pick up the prey. We tested the ability of the gumfoot threads to store energy by cyclic loading tests, enabling measurement of energy input and output. Our tests show that gumfoot silk is very efficient (81%) at low strain (<2%) but not efficient (24%) at higher strains (5-10%). Low-strain efficiency in spider silks has not been previously measured, so silk was thought to act as a shock absorber (energy dissipation) rather than a spring (energy storage). Our initial observations of intact gumfoot threads in the web are consistent with this spring hypothesis. Our stress-strain analysis shows that gumfoot silk has nearly identical material properties as dragline silk. They both show an initially stiff region followed by a distinct decrease in stiffness as the silk is stretched beyond 2% of its original length. This yield point suggests a significant change in the way that the silk molecules resist being stretched. Therefore, the two silks can have identical properties yet exactly the opposite function (energy storage as opposed to energy dissipation) because the spider uses the silks at different strains. (Added 5 / 12 / 2002)

Envenomation by Centruroides scorpions
 Author: Leslie Boyer  Institution: University of Arizona
 Abstract: In North America, approximately 8 species and subspecies of Centruroides scorpion are significantly neurotoxic to humans. Venom includes sodium channel neurotoxins that provoke a clinical syndrome affecting nicotinic, muscarinic and neuromotor systems. Children in particular are susceptible to neurotoxicity, of sometimes life-threatening severity. Treatment varies widely with local medical capabilities, traditions, and laws. Currently there is no scorpion antivenom approved for use in the United States, but efficacy has been demonstrated both with an Arizona State University goat immunoglobulin product and, in Mexico, with an equine F(ab)2 product. Efforts are under way to demonstrate cross-protection using the Mexican antivenom against envenomation by the US species. (Added 5 / 17 / 2002)

Diurnal Use of Artificial Shelters by Harvestmen in Experimental Gardens
 Authors: Sarah Bradbury and Alan Cady  Institution: Miami University, Oxford, Ohio
 Abstract: Harvestmen (Opiliones) are a Generalist Predatory Arthropod and are usually numerous and common in gardens. Little is known of how they may contribute to suppression of herbivore activities in such habitats if their populations were augmented. Previous results from experimental enclosures show that brussel sprouts plants in the presence of harvestmen had greater growth and less damage from herbivores. These experiments were continued with cucumbers and to test the effects of small lean-to shelters designed to provide harvestmen with favorable microhabitats during the day to prevent their leaving to seek shelter from daytime heat and desiccation. Twelve 2X2 meter metal flashing enclosures holding cucumbers and brussel sprouts were erected. Six of the 12 enclosures contained 15 harvestmen each, uniquely marked to denote treatment. Three enclosures with and three enclosures without harvestmen were supplied with 8 25X25 cm lean-to shelters. Each of 4 treatments (harvestmen with shelters; harvestmen without shelters; no harvestmen with shelters; and no harvestmen, no shelters) were replicated three times. Harvestman positions were noted during nocturnal and diurnal censuses and observations. Herbivore plant damage, fruit yields, and biomass were measured. Harvestmen chose the shelters during the hotter, drier daytime, and were found out on vegetation at night. Thus, shelters may reduce harvestman emigration out of gardens during the day, inducing them to remain in positions to prey upon pests or their eggs at night. Plants in the presence of harvestmen showed trends for less damage and higher fruit yields, especially during mid-season. (Added 5 / 16 / 2002)

Papillae on the Pedipalps of Solifugae: structure and proposed function
 Authors: Jack Brookhart and Paula Cushing  Institution: Denver Museum of Nature & Science
 Abstract: Some male solifugids have a series of conical structures called papillae on the ventral surface of the metatarsal segment of their pedipalps. We present the first known images of the microstructure of these papillae and present our hypothesis as to their function. (Added 5 / 7 / 2002)

Clinical Aspects of Envenomation by Black Widow Spiders
 Author: Sean Bush  Institution: Loma Linda University Medical Center
 Abstract: Clinical signs and symptoms following black widow spider envenomation may include severe muscular pain, high blood pressure, and profuse sweating. Initially, a bite may cause sharp pain or go unnoticed. The lesion following the bite typically has a "target" appearance, i.e., central reddened puncture site surrounded by blanching and an outer halo of redness. Unlike brown recluse bites, the skin around the bite site does not rot. Pain may progress from the bite site gradually to involve muscles in the limbs, abdomen, back, and/or chest. Abdominal pain may mimic surgical conditions. Patients may complain of a headache and develop facial swelling, called Latrodectus facies. Nausea and vomiting may ensue. Sweating may be isolated to the area surrounding the bite or may be generalized. The envenomation syndrome usually manifests within an hour, reaches maximum intensity within 12 hours, and can last for days to weeks. There is antivenom for black widow spider bites. However, there has been a death attributed to an allergic reaction to this antivenom, so most U.S. doctors opt to treat patients' symptoms with pain medications, such as morphine, and sedatives, such as valium. Interestingly, Australian red-back spider antivenom works for U.S. black widow spider envenomation. Calcium has been reported to be no more effective than placebo and is no longer recommended. Although around 2,500 black widow spider bites were reported last year to the American Association of Poison Control Centers, no deaths have ever been reported to Poison Control since its first report in 1983. (Added 5 / 7 / 2002)
Spiders in Texas Pecans: Are They Affected by Fire Ants?
 Authors:Alejandro Calixto, Allen Dean,
Allen Knutson, Marvin K. Harris
and Bill Ree
 Institution: Texas A&M University
 Abstract: Imported Fire Ants (IFA) are known to interfere with natural enemies in pecans. This ecological disruption may contribute to pest outbreaks by preying on natural enemies. We investigated this effect on spiders associated with the pecan agroecosystem. The study was conducted in a pecan orchard (Robertson Co., TX). Plots treated for IFA were compared with untreated, three treatments were established and replicated four times; 1. untreated controls; 2. chlorpyrifos (Lorsban 4E TM) as a trunk treatment (was used as a chemical barrier to impair ants to climbing up the tree) and; 3. broadcast methoprene (ExtinguishTM) bait treatment that reduced IFA densities by 70%. Ground and foliage spiders were studied by using 4 pitfall traps and 200 artificial refuges per treatment weekly, monitoring from May 2000 thru May 2002. Refuges consisted of strips of corrugated cardboard (6x3 in) attached to the terminal twigs of the tree and inspected every week from April 2001 thru May 2002. A total of 15,588 spiders were collected in all, 3,372 in pitfall traps and 12,216 in corrugated strips. 127 species distributed into 26 families were recorded during the study, 77 species occurred in refuge strips, 94 species in pitfall traps and 44 species in both methods. Results suggested that spider densities were not affected by IFA directly but effect over other natural enemies may cause an increase in numbers in control plots due to lack of high intraspecific competition. Untreated plots tended to have more spiders compared with treated. Spiders seem to be present year round on the tree/ground playing an important role as a "buffer" predator over pest outbreaks. while multivoline insect predators (lacewings and lady beetles) vary considerably in conjunction with prey availability and often occur at very low densities. Spiders consistently occur at reasonably stable densities. (Added 6 / 10 / 2002)

Geographic variation in prey capture in a colonial orb-weaving spider
 Authors: Florencia Fernández Campón
and Susan E. Riechert
 Institution: University of Tennessee, Knoxville
 Abstract: Prey availability affects tolerance and cooperation in spiders. Individuals from populations from habitats with high prey availability showing higher levels of cooperation. In addition, temporal variation in prey availability could be affecting plasticity levels with which individuals respond. Populations changing their behavior to adapt to local conditions favored against populations lacking that plasticity. <Parawixia bistriata> is a colonial spider in which cooperative capture is facultative. By doing reciprocal transplants in habitats with different prey availability and seasonality we evaluated the hypotheses of a) higher cooperation under high prey levels, b) more plasticity when temporal variation in prey level existed. In manipulative studies we observed the response towards prey of increased size based on number of individuals participating in capture, in communal feeding and latency of the feeding group to divide. We expected more individuals participating in prey capture and feeding under higher prey conditions as well as longer durations of the feeding groups, indicating higher tolerance as well. Populations differed in their response but not as expected. Despite the low sample size, data from transplants suggest that dry populations present more plasticity, behaving like native populations when trasplanted to wet habitats, whereas wet populations maintained their behavior under different levels of prey. (Added 5 / 31 / 2002)

Abundance patterns, stream use and overwintering in a community of stream-bank cursorial spiders
 Authors:Karen Cangialosi, Sharon Martinson and David Cook  Institution: Keene State College
 Abstract: While spiders are predominately terrestrial, a few species are known to enter aquatic environments for most or some of their lives. Spiders living along a stream bank may make use of the water flow for foraging for aquatic organisms or for dispersal. The objectives of this study were to document annual abundance patterns for the community of stream-bank cursorial spiders and to quantify their degree of entry into the stream drift. A drift net was placed in each of three stream sites in forested areas in Cheshire County, New Hampshire and net contents were collected and recorded twice a week for approximately one year. Simultaneously, pitfall traps were placed along three, 30m transects adjacent to each stream and contents were collected and recorded once a week. Air temperature, water temperature, and water level were also recorded at each sampling period. We found that most species had non-overlapping periods of peak abundance, and that most species that were along the stream margins did not enter the drift. However, two species of Dictynids, (Circurina) entered the drift in large numbers in early December when the average daily temperature reached below freezing. It it possible that these species may be using the streams to locate suitable overwintering sites. (Added 5 / 13 / 2002)

Are mechanoreceptors involved in the neural circuitry of scorpion peg sensilla?
 Author: Steven Carter and Douglas Gaffin  Institution: University of Oklahoma
 Abstract: Scorpion pectines are paired, ventral appendages that extend from their eleventh body segment. Each pecten resembles a comb with a jointed spine connecting numerous teeth. The ventral surface of each tooth contains a dense patch of truncated hairs, called peg sensilla. Morphological and electrophysiological studies have concluded that numerous chemoreceptive neurons are present in each peg while only one mechanoreceptor is present. Synaptic interactions between chemosensitive cells have been identified via cross-correlation analysis; however, the mechanoreceptor has received very little attention, and it is unknown if it is part of the peg circuitry. Our research focused on the general characteristics and roles of the mechanoreceptors in peg sensilla of the desert grassland scorpion (Paruroctonus utahensis). Extracellular electrophysiological recordings were obtained from the bases of individual pegs during mechanical stimulation. These recordings were then segregated into individual cellular firings using wave-form analysis, which showed the existence of at least four different waveforms (three putative chemoreceptors and one mechanoreceptor). Cross-correlation analysis did not reveal signs of synaptic interaction between the mechanoreceptor and two of the chemoreceptors while a third was inconclusive. Taken together with previous morphological studies it appears that the chemoreceptors and mechanoreceptors form synaptically isolated neural populations in scorpion peg sensilla. (Added 5 / 12 / 2002)

Ultrastructure of the Major Ampullate Gland of the Black Widow spider, Latrodectus hesperus
Authors and Institutions
Merri Lynn Casem California State University, Fullerton 
LPP Tran Pitzer College
Anne M.F. Moore University of the Pacific
 Abstract: Silk production in the spider occurs within specialized glands that are capable of the synthesis of large fibrous proteins and the post-translational processing of those proteins to form an insoluble fiber. The major ampullate gland of Latrodectus hesperus (black widow) is similar in morphology to those found in the Araneid spiders. The tail domain of this gland is highly protein synthetic, giving rise to a core protein product. The silk product is transported to the ampullar region where it is stored. The cells of the ampulla wall produce an electron dense material that appears to form a "skin"; surrounding the silk "core"; generated in the tail. The duct of the gland consists of at least two distinct cell types. One type contains 'honeycomb' vesicles of unknown function while the other possesses elaborate microvilli that may be involved in the reabsorption of water and subsequent dehydration of the silk. The duct is reinforced with a chitinous cuticle. As the silk product transits through these various stages of assembly it can be seen to undergo a condensation or concentration, possibly reflecting the influence of both the dehydration and shear forces that occur within the duct. (Added 5 / 13 / 2002)

Spider Diversity of Orchid Island, Taiwan: A Comparison Between Habitats generated from various aboriginal activities
 Authors: Kuan-Chou Chen and I-Min Tso  Institution: Tunghei University, Taichu, Taiwan
 Abstract: Tropical forests exhibit very high spider diversity, but due to the difficulties of conducting comprehensive sampling in tropical areas relevant studies are quite rare. Orchid Island is a tropical island 91 km off the southeast coast of Taiwan. The forests on this island are the northern most tropical forests in East Asia. In this study, the spider diversity of Orchid Island was studied and those from three types of habitats generated by various kinds of aboriginal activities were examined. Habitat type studied in this study included the forest interior, the meadow outside the forest and the forest edge. All habitat types had four replicates located in Yonsing farm, Yeying village and Chungshing farm respectively. In each replicate four 5m X 5m sampling plots were established. In addition, we also set up additional 8 plots in the relatively undisturbed forest in Tienchi for comparison. Three field trips were conducted in August, 2000 and February and April, 2001. Spiders were collected by six methods (pitfall traps, litter substraction, shrub sweeping-net, day and night hand collection and canopy sweeping-net ) to have a comprehensive representation of diversity from all microhabitats in the plot. From the adult specimens obtained, a total of 110 species from 18 families were identified. Shannon-Weaver function, Simpson index and Evenness were not significantly different among habitat types, suggesting a similar dominance pattern island-wide. However, species composition differed considerably among different types of habitats. Result of a UPGMA analysis using pair-wise Euclidean distance demonstrated that specimens from 56 plots can be divided into seven major groups, with Tienchi plots united as a unique cluster. In addition to species composition, foraging guild composition also differed significantly among habitat types. These results suggest that the diversity of ground spiders in Orchid Island tropical forest is quite heterogeneous. Spider diversiy in disturbed area did not constitute a subset of those in the relatively undisturbed area. (Added 5 / 15 / 2002)

Detritus decoration built by Cyclosa confusa may not function to improve foraging or concealing
 Authors: I-Chia Chou and I-Min Tso  Institution: Tunghei University, Taichu, Taiwan
 Abstract: In some orb-weaving spiders, in addition to regular components of web they also construct extra structure known as decorations on web. Besides silk, decorations built by many species of the genus Cyclosa are composed of debris, leaf and egg sacs. So far, there is no direct test of the functions of these debris decorations built by Cyclosa spiders. Although direct support is lacking, debris decorations are traditionally believed to function as a camouflaging device. In this study, we test this hypothesis by comparing the mortality of C. confusa with or without detritus decorations on their webs. Besides, prey remains deposited on the webs of the social spiders Mallos gregalis had been shown to be capable of attracting prey insects to spider webs. Therefore in this study we also examined if C. confusa webs decorated with prey remains intercept more prey than undecorated ones. Two field studies were conducted in a tropical forest in Orchid Island, Taiwan in February and April, 2002. Results from both field trips showed that no significant difference was found in prey interception rates between experimental group (decoration removed) and control group (decoration remained). Similarly no significant difference was found in mortality rates between experimental and control groups in our February study. However, results of our April study indicated that C. confusa with decorations suffered significantly higher mortality than those where decorations were experimentally removed. These results suggest that detritus decorations of C. confusa do not seem to function to increase insect catching or to decrease mortality rate. Instead, detritus decoration may even be a cost to C. confusa by increasing the mortality rate. Why C. confusa consistently build decorations on their webs given the cost of increasing mortality rate awaits future study. (Added 5 / 15 / 2002)

An Inventory of the Spiders of the Great Smoky Mountains National Park
 Author: Frederick Coyle  Institution: Western Carolina University
 Abstract: The key objectives of this project are to determine what spider species live in the Great Smoky Mountains National Park (GSMNP) and how they are distributed among the park's habitats. The primary sampling protocol involves a team of collectors using four standardized methods that sample spiders in most microhabitats and vegetation strata. This protocol yields large and statistically tractable replicate data sets that reflect the relative abundance of species in the sites and habitats studied and will facilitate comparisons of species richness, taxonomic composition, and guild structure among diverse communities and regions. We have collected 2010 1-hr ground, aerial, beat, and sweep samples, and 450 1 m sq. litter samples, containing an estimated 52,000 adult spiders from 17 intensively sampled focal sites representing 16 of the park's major habitats and from accessory sites representing additional habitats. Eighty percent of these adult spiders have been sorted to morphospecies, 40% have been identified, and 20% have been entered into a Biota database. The identified spiders comprise 482 species, 36 of which appear to be undescribed. Products of this inventory will include a Biota database available on the internet, a monographic guide to GSMNP spiders (in CD or DVD format), and a pocket guide for park visitors. Published papers based on inventory data describe the spider assemblage structure at selected sites, evaluate the effectiveness of species richness estimators, and describe the habitat distribution patterns, life cycles, and behaviors of species of Araneus, Tetragnatha, Neriene, Theridion, and Pirata. (Added 5 / 14 / 2002)

The Effects of Altered Precipitation on Leaf Litter Spider Communities
 Author: Kenneth Cramer  Institution: Monmouth College
 Abstract: At Oak Ridge National Labs in Tennessee, a long-term manipulative experiment was initiated in 1993 to study the potential impacts of precipitation change due to global warming in a temperate deciduous forest. The Throughfall Displacement Experiment (TDE) diverts 33% of ambient rainfall from one 80x80m plot to another. I evaluated the impacts of the TDE on spider abundance and species richness and composition. Samples of leaf litter from 0.2m^2 circular plots taken in August and November from the wet, ambient (control), and dry plots were hand sorted for spiders. Leaf mass (as an estimate of leaf volume and habitat area) had a significant positive correlation with spider abundance, more so of selected taxa, especially Dictyna. Total spider bundance was unchanged across treatments, although leaf mass was significantly greater in the dry plots. Changes in species richness were minimal, yet rare species may have been adversely affected by moisture changes. Species composition, however, was affected by the treatments (as well as by slope and season), and certain species showed distinct habitat associations correlating with treatment or slope of the experimental plots. (Added 5 / 15 / 2002)

Cryptic Vicariance in Homalonychus (Araneae, Homalonychidae)
 Authors:Sarah Crews and Marshal Hedin  Institution: San Diego State University
 Abstract: When a vicariant event has occurred in the past, but is not readily detectable by analysis of morphology alone (i.e., two or more morphological groups are not apparent), this vicariance is said to be cryptic. Detection of cryptic vicariance is important for studies of conservation and biodiversity, as well as for elucidating biogeographic histories. Cryptic vicariance has been shown to occur in numerous vertebrate taxa distributed on the Baja Peninsula, where molecular analyses reveal deep phylogenetic splits in morphologically homogeneous taxa. Here we report the first evidence of cryptic vicariance in Baja for an invertebrate group, the spider family Homalonychidae. Using mtDNA data we have detected a deep molecular split between northern and southern populations of Homalonychus theologus on the Baja Peninsula. Roth (1984) made no mention of genitalic variation within H. theologus, although he highlighted considerable variation in the congeneric H. selenopoides. This north ­ south split may correspond to a mid-peninsular seaway that existed around 1.6 mya. (Added 5 / 13 / 2002)

Title: Spider Genera of North America Revision Project
 Author: Paula Cushing  Institution: Denver Museum of Nature & Science
Abstract: In September 2001, a team of taxonomists and interested arachnologists proposed to the American Arachnological Society Executive Committee that the Spider Genera of North America guide by Vince Roth be revised. The Spider Genera of North America Revision Team, or SGNART, consists of Paula Cushing, Darrell Ubick, Suzanne Ubick, Don Buckle, Mike Draney, Nadine Dupérré, Jack Kaspar, Pierre Paquin, Dave Richman, and Barbara Roth. The SGNART proposes to have the revision completed by the end of 2004. This poster serves both as an overview of the revision project as well as a solicitation for assistance from interested taxonomists who wish to assist in this revision. Taxonomists who contribute a major revision of a particular taxonomic group will receive chapter authorship. (Added 4 / 19 / 2002)

Semi-heavy Metal: Calcium, Manganese and Zinc in the Oral Cuticle of the Tarantula, Stichoplastus sanguiniceps (Araneae: Theraphosidae)
 Author: Bruce Cutler  Institution: University of Kansas
 Abstract: It has been known since 1989 that some spider sclerotized cuticle contains high concentrations of manganese (Mn) in the tarsal claws, and zinc (Zn) in the fangs. I examined the molted exoskeleton of Stiphoplastus sanguiniceps, a small Trinidadian tarantula for the presence of divalent metals. The specimens were collected after molting and frozen at -4 oC until use. Cuticle areas of interest were removed and mounted on aluminum stubs with silver paint. After drying specimens were sputter coated with 10 nm of gold or gold-palladium alloy. A Leo 1550 field emission scanning electron microscope (SEM) equipped with an EDAX energy dispersive x-ray spectroscopy system was used to provide topographical and compositional information about the specimens. Both individual x-ray spectra and compositional maps were taken from the different areas of the chelicerae and fangs. As expected the fangs' surface contained significant levels of Zn. The surface of the cheliceral teeth contained elevated levels of Mn. Non-cheliceral tooth regions of the chelicerae did not contain elevated levels of any metals. An unexpected finding was the presence of high levels of calcium (Ca) in the non-surficial fang citicle. High levels of Ca are unusual in terrestrial arthropod cuticle, except for isopods and millipedes. Mn and Zn also occur in hymenopterous cuticle where they have been intensively investigated. Supposedly they confer toughness on cuticle containing them, but the mechanism for this is still unknown. Future work will examine the distribution of these elements in oral cuticle within different spider taxa, and look at non-molted as well as molted exoskeleton. (Added 5 / 6 / 2002)

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D through F

EVOLUTION OF SPERMATHECAL STRUCTURES WITHIN THE SPIDER FAMILY TETRAGNATHIDAE
 Author: Anne Danielson-Francois Institution: University of Arizona
 Abstract: The study of arachnid genitalic structures is useful from the perspectives of systematics and sexual selection. Spider genitalia have been used as a taxonomic tool for distinguishing between taxa and by evolutionary biologists to test mechanisms of sexual selection by which the variation could evolve, ranging from Fisherian run-away selection, chase-away selection, and sperm competition. While many species have been dissected at a gross level, few detailed studies exist that examine female spermathecal ducts, spermathecal accessory glands and their gland pores. Hypotheses have been proposed to explain both male behavior and the outcome of sperm competition based on the number and location of spermathecal ducts alone. Far less attention has been paid to the spider spermathecal gland pores, which penetrate the cuticular wall of the spermathecae, allowing glandular secretions to pass into the lumen of the spermathecae. The spider family Tetragnathidae has particularly variable spermathecal morphologies, ranging from entelegyne to haplogyne genitalic characters. Sixteen representative members of this family and five outgroup taxa were examined with scanning and transmission electron microscopy in order to describe the fine structure of spermathecae, including the distribution and density of spermathecal gland pores. The function(s) of the glandular secretion are unknown. The distribution and density of spermathecal gland pores is discussed with regard to possible functions of the glandular secretion. The potential influence of spermathecal gland secretions on mating behavior and sperm competition is discussed. (Added 5 / 14 / 2002)

Inventory of linyphiids from burned and unburned oak woodland/savanna habitats in Chicago, Cook Co., Illinois

Authors and Institutions
Michael L. Draney University of Wisconsin-Green Bay
Petra Sierwald Field Museum of Natural History, Chicago
Nina Sandlin Field Museum of Natural History, Chicago

 Abstract: Swallow Cliff is a mature remnant oak woodland/savanna complex; Open woodlands such as these are highly endangered globally by development and invasive vegetation. Ground spiders were sampled biweekly during growing seasons of four years (1996-1999) at four sites using pitfall traps as well as Berlese-extracted leaf-litter samples, flight-intercept traps, and carrion-baited pitfall traps. This yielded 14,166 adult spiders in 159 species and 21 families. Linyphiidae was the 2nd most abundant family (19.0% of total adults) after Thomisidae (42.7%), but was by far the most diverse family with 52 species (32.7%) in 22 genera; Salticidae was 2nd with 14 species (8.9%). This includes 20 linyphiids new to Illinois, and one species (Walckenaeria palustris) found for the first time within the United States. The assemblage is composed of species characteristic of both field as well as forest communities. All the species are broadly distributed across the northern and/or eastern portions of North America and can be considered part of the generalized Great Lakes fauna rather than prairie biome habitat specialists. The herbaceous component of two of the sites was experimentally burned prior to the 1999 sampling. Six of nine abundant species (n > 30) increased or decreased their proportional representation by over 50% during the post-burn year at the burned sites, compared with four of eight species during the same period at the unburned sites. Thus, although the linyphiid fauna of the burned sites changed more dynamically, some of the observed change is apparently due to normal year-to-year variation. (Revised 5 / 31 / 2002)

Title: The Present Status and a Review of the Brown Recluse and Related Spiders, Loxosceles spp. (Araneae: Sicariidae), in Florida.
 Author: GB Edwards  Institution: Florida State Collection of Arthropods, Gainesville
 Abstract: Spiders of the genus Loxosceles have only been collected in 8 of the 67 counties in Florida. The native brown recluse spider, L. reclusa Gertsch and Mulaik, has been found in Alachua, Bay, Duval, Jefferson, and Leon counties, all in the northern part of the state. The introduced Mediterranean recluse, L. rufescens (Dufour), has been found in Orange, Osceola, and Dade counties, in the central and southern areas of the state. All records have been interceptions of single specimens or of established populations in one or two buildings. There is no evidence of a widespread population of recluse spiders in Florida, nor is there any evidence that there are frequent interactions between recluse spiders and humans in the state. Despite hundreds of diagnoses by medical personnel of brown recluse spider bite in Florida every year, there has been only one instance where an alleged bite was accompanied by an actual specimen of a brown recluse spider. Doctors should be aware of multiple other causes of apparent pre-necrotic and necrotic wounds, and only suspect spider bite as a last resort in regions where recluse spiders are not endemic. (Added 5 / 3 / 2002)

Litter and ground surface dwelling spiders of mixed mesophytic forests in southeast Louisiana
 Author: Joyce Fassbender  Institution: Louisiana State University
 Abstract: Mixed mesophytic hardwood forests are composed predominantly of magnolia, holly, and beech with a mixture of other tree species, such as oak and hickory, and a distinct understory. Remnants of mixed mesophytic hardwood forests in the southern United States are important refugia for disjunct and habitat-restricted species. In Louisiana, mixed mesophytic forest habitat is found mostly in West Feliciana Parish. I chose two sites to conduct a study of spider diversity in litter habitats of disturbed and mature mixed mesophytic forests. Berlese sampling was used to collect 10-kg samples of forest litter twice monthly from both sites. Collections were made from October 1998 to October 1999. I collected 1725 adult specimens representing 89 species in 14 families. At the mature forest site (Tunica Hills WMA) I collected 909 adult specimens, 58 species in 12 families. At the disturbed forest site (Feliciana Preserve) I collected 816 adult specimens, 73 species in 12 families. Species accumulation and richness estimators indicated the likelihood that additional species were present but not collected during the sampling period. The disturbed site had significantly greater species diversity and more uncommon species, perhaps because of a wider variety of microhabitats and presence of tourist and colonizer species. The mature forest site was less diverse, perhaps as a result of more stable and homogeneous habitat. Multiple disjunct species with northern affinities were found. Additionally, twelve species that had not been previously reported in Louisiana were discovered. (Added 5 / 15 / 2002)

Title: New data on "Euscorpius carpathicus" species complex (Scorpiones: Euscorpiidae) from Italy, Malta, and Greece: evidence from mitochondrial DNA and morphology
  Authors: Victor Fet (1),
Michael E. Soleglad (2),
Benjamin Gantenbein (3),
Valerio Vignoli (4),
Nicola Salomone (4),
Elizabeth V. Fet (1) and
Patrick J. Schembri (5)
 Institutions: (1) Department of Biological Sciences, Marshall University, Huntington, WV 25755-2510, USA
(2) P.O. Box 250, Borrego Springs, CA 92004, USA
(3) Institute of Cell, Animal and Population Biology, Ashworth Laboratories, The University of Edinburgh, Edinburgh EH9 3JT, Scotland
(4) Department of Evolutionary Biology, University of Siena, 53100, Siena, Italy
(5) Department of Biology, University of Malta, Msida, MSD 06, Malta.
 Abstract: The first mitochondrial DNA phylogeny (based on 16 unique haplotypes) is presented for a number of scorpion populations from Italy, Malta, and Greece, previously classified under a "catch-all" name of Euscorpius carpathicus (L., 1767) (Fet & Sissom, 2000). The comparative analysis of mitochondrial gene for 16S (large subunit) ribosomal RNA suggests that at least two clearly separated lineages are present. However, neither of these belongs to E. carpathicus (L.) in strict sense (which is limited to Romania; Fet & Soleglad, 2002). The first, "western" lineage, found in northern and central Italy (also present in southern France, Slovenia, Croatia, and Austria) is identified as E. tergestinus (C.L. Koch, 1837) according to Fet & Soleglad (2002). Here, we identify another monophyletic, "southern" lineage as E. sicanus (C.L. Koch, 1837), originally described from Sicily; it includes as new synonyms the following seven subspecies: E. carpathicus canestrinii (Fanzago, 1872) and six subspecies described by Caporiacco (1950): E. c. calabriae, E. c. ilvanus, E. c. garganicus, E. c. argentarii, E. c. palmarolae, and E.c. linosae. Morphology also confirms the existence of two lineages; of those E. sicanus is characterized by unique trichobothrial pattern and number where series eb (and in some populations, also series eba) have 5 trichobothria (instead of always 4 in E. tergestinus). The E. sicanus lineage is found in southern Italy (with Sicily and Sardinia), Malta, northern Africa (Tunisia, Libya), Madeira, and southern Greece. The enigmatic "E. mesotrichus" (Kinzelbach, 1975) from Greece (Thessaly) belongs to this species. (Added 3 / 21 / 2002)

Sexual selection favors large body size during opportunistic mating in male Argiope aurantia

Authors and Institutions
Matthias Foellmer Concordia University
Daphne Fairbairn UC Riverside

 Abstract: During their quest to maximize fertilization success, male Argiope aurantia may face a cannibalistic attack by the female. However, males are protandrous and are often observed cohabiting with penultimate females, with usually more than one male present per web. While the female undergoes her molt to maturity males try to copulate with the then defenseless female, which is known as opportunistic mating. Here, we investigate the fitness consequences for males resulting from the ensuing competitive interactions among them. In order to estimate male mating success we caged those males that were found with penultimate females close to molt with their respective females. We measured male prosoma width and patella-tibia length of the first leg pair. Pedipalps of males were checked for signs of insertion before and after caging, and we performed three scan samples per day. A trial was over once the female had molted. Both prosoma width and leg length were positively and significantly associated with mating success, but not independent of each other. This suggests a general pattern of selection for large size, and this was independent of number of males present per female. Further, position of a male at the last scan before the female's molt was an important predictor of mating success, but this was unrelated to male size. We put these findings into context by evaluating the relative occurrence of opportunistic mating and conclude that selection for large male size is important in this species, despite the fact that males are much smaller than females. (Added 5 / 15 / 2002)

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G through I

Polynesian Voyagers: Phylogenetic relationships among Hawaiian Crab Spiders (Araneae: Thomisidae)
 Authors: Jessica Garb and Rosemary Gillespie  Institution: University of California, Berkeley
 Abstract: Spiders of the family Thomisidae are characterized as ambush predators that employ color mimicry of plants to capture prey. The twenty described species of Hawaiian thomisids exhibit a diversity of plant host affiliations and host-specific cryptic coloration. This diversity led previous systematists to place the Hawaiian species into several different genera, suggesting that they descended from several independent colonization events to the archipelago. Recently, all Hawaiian species were hypothesized to comprise a monophyletic group having undergone dramatic morphological diversification subsequent to colonization. This hypothesis is tested with a phylogenetic analysis of molecular sequence data. Specifically, a 525 bp region of the nuclear gene elongation factor 1-a , containing two exons separated by a 168 bp intron, was sequenced from Hawaiian representatives as well as closely related taxa from North and South America, Africa, and several islands of French Polynesia. We compare the resulting phylogenetic hypothesis with another generated from previously collected mitochondrial sequence data, and determine the combinability of the two data sets for a total evidence analysis. The resulting hypothesis is used to assess levels of speciation following initial colonization and whether specific colorations exhibited among the species have repeatedly evolved. (Added 5 / 15 / 2002)

Spiders on the Storm: Adaptive Radiation on Pacific Archipelagos
 Author: Rosemary Gillespie  Institution: University of California, Berkeley
 Abstract: Adaptive radiation involves the diversification of species to exploit different ecological roles, with related adaptations. It is associated with the occupation of new environments that are sufficiently isolated as to allow colonists to diversify by filling multiple ecological roles. How is the diversification achieved? I have been studying spiders in the genus Tetragnatha in order to elucidate commonalities underlying patterns of adaptive radiation. In this talk I will first compare three archipelagoes of differing isolation across the Pacific and show that the genus has diversified within each, although the lineages are unrelated to each other. Second, I compare different lineages within the Hawaiian Islands, where the diversification is the most prolific, to determine how species differentiation is occurring within the archipelago. I show that one clade, the spiny-leg clade, has progressed down the island chain, with species on any one island most closely related to others on the same island. Moreover, the same set of ecological forms has evolved repeatedly, filling the ecological space in a similar manner and allowing multiple species to co-occur. However, another clade of spiders, a web-building clade, is ecologically conservative, and has differentiated between geographic areas only, with a single representative of the clade at any one site. The general conclusion is that adaptive radiation has occurred in multiple lineages of Tetragnatha in the Pacific, and has done so independently, with multiple mechanisms underlying diversification. (Added 4 / 26 / 2002)

The systematics of spiders of the Hadrotarsus-group (Araneae, Theridiidae)
 Author: Mark Harvey  Institution: Western Australia Museum, Perth W.A. Australia
 Abstract: The Hadrotarsidae were once considered amongst the rarest and least known of all spider families and, accordingly, have been thought to represent relatives of the Theridiidae, Oonopidae and Tetrablemmidae, amongst others. The discovery that hadrotarsids were simply a highly autapomorphic sub-group of the Theridiidae (Wunderlich, 1978, Forster, Platnick and Coddington 1990) and were placed with genera such as Euryopis, Dipoena, Anatea and Yoroa in an expanded Hadrotarsinae. A revision of those hadrotarsine spiders with reniform posterior median eyes ­ the Hadrotarsus-group ­ has revealed five genera and 27 species (22 of which are new) from Australia and southern New Guinea. The bulk of the diversity lies within just two genera, Hadrotarsus and Gmogala, which contain 12 and 11 species respectively. Three new genera are recognised, two of which appear to retain at least one plesiomorphic feature, the accessory spermathecae found in other members of the Hadrotarsinae such as Euryopis and Dipoena. A comprehensive examination of the phylogenetic relationships within the Hadrotarsus-group supports the monophyly of each of the five genera, and provides some structuring within Hadrotarsus but not within Gmogala. Many hadrotarsine species are found to possess wide distributions that are consistent with dispersal mechanisms such as ballooning. Most species are found in the drier woodand regions of Australia, with very few found in rainforests, suggesting a radiation during the late Tertiary following the onset of arid climatic patterns across Australia during the Miocene. (Added 4 / 29 / 2002)

Evolution of Adhesive Mechanisms in Cribellar Spider Prey Capture Thread: Evidence for Van der Waals and Hygroscopic Forces
 Authors: Anya Hawthorn and Brent Opell  Institution: Virginia Tech
 Abstract: Sticky prey capture threads are produced by many members of the spider infraorder Araneomorphae. Cribellar threads are plesiomorphic for this clade, and viscous threads are apomorphic. The outer surface of cribellar thread is formed of thousands of fine, looped fibrils. Basal araneomorphs produce non-noded cribellar fibrils, whereas more derived members produce noded fibrils. Cribellar fibrils snag and hold rough surfaces, but other forces are required to explain their adherence to smooth surfaces. Threads of Hypochilus pococki (Hypochilidae) formed of non-noded fibrils held to a smooth plastic surface with the same force under low and high humidities. In contrast, threads of Hyptiotes cavatus and Uloborus glomosus (Uloboridae) formed of noded fibrils held with greater force to the same surface at intermediate and high humidities. This supports the hypothesis that van der Waals forces allow non-noded cribellar fibrils to adhere to smooth surfaces, whereas noded fibrils, owing to the hydrophilic properties of their nodes, add hygroscopic forces at intermediate and high humidities. Mathematical models of these forces are consistent with the observed stickiness of cribellar thread. Thus, there appear to have been two major events in the evolution of adhesive mechanisms in spider prey capture thread: the addition of hydrophilic nodes to the fibrils of cribellar threads and the replacement of cribellar fibrils by viscous material and glycoprotein glue. (Added 5 / 15 / 2002)

Genealogical Exclusivity in Geographically Proximate Populations of Hypochilus thorelli Marx (Araneae, Hypochilidae) on the Cumberland Plateau of North America
 Author:Marshal Hedin and Dustin Wood  Institution: San Diego State University
 Abstract: The issue of sampling sufficiency is too infrequently explored in phylogeographical analysis, despite both theoretical work and analytical methods that stress the importance of sampling effort. Regarding the evolutionary pattern of reciprocal monophyly, both the probability of recovering this pattern, and the possible inferences derived from this pattern, are highly contingent upon the density and geographic scale of sampling. Here we present an empirical example that relates directly to this issue. We analyze genetic structure in the southern Appalachian spider species Hypochilus thorelli, using an average sample of five mtDNA sequences per location for 19 locations. All sampled sites are reciprocally monophyletic for mtDNA variation, even when separated by geographic distances as little as five kilometers. For populations separated by greater geographic distances of 20-50 kilometers, mtDNA sequences are not only exclusive, but are also highly divergent (uncorrected p-distances exceeding five percent). Although these extreme genealogical patterns are most seemingly consistent with a complete isolation model, both a coalescent method (Slatkin 1989) and nested cladistic analysis (Templeton et al. 1995) suggest that other restricted, but non-zero, gene flow models may also apply. Hypochilus thorelli appears to have maintained morphological cohesion despite this limited female-based gene flow, suggesting a pattern of stasis similar to that observed at higher taxonomic levels in Hypochilus. (Added 5 / 12 / 2002)

Use of a micro-engineered chemical delivery device to evaluate scorpion peg sensillum response to organic stimulants
 Authors: Mujahid Hines and Douglas Gaffin  Institution: University of Oklahoma
 Abstract: Scorpions are nocturnal animals with a rich array of finely tuned sensory structures. In particular, mid-ventral appendages called pectines are complex chemosensory organs that are used in the detection of food and mates. Previous electrophysiological studies have shown that the sensory elements on pectines (thousands of minute peg-shaped sensilla) are sensitive to a variety of volatile organic compounds. However, the stimulus delivery mechanism used in these studies was imprecise, making it difficult to compare response patterns among peg sensilla. We have engineered a new device to allow chemical stimulants to be more precisely delivered to a small group of pegs. We tested the efficacy of the engineered device and its dynamics by designing a series of stimulations using 1-hexanol and mineral oil as the control chemical. Peg sensilla on the pectines of Paruroctonus utahensis and Paruroctonus mesaensis were recorded extracellularly while being stimulated to record the elicited response pattern. We have completed preliminary testing of the delivery device, including optimal duration of stimulus pulse and the best size for the nozzle bore. This device will be used to investigate a basic question of pectine functionality: do all peg sensilla respond with the same pattern of neural activity or are there distinct inter-peg differences? The latter would suggest a segmentation of chemical information at the level of the peg, similar to the olfactory epithelium of mammals. (Added 5 / 12 / 2002)
Sosippus, revisited
 Authors: Maggie Hodge and Sam Marshall  Institution: Hiram College
 Abstract: The vast majority lycosids are vagrant hunters, either lying in wait for prey or wandering in search of prey. A few species are sedentary, building more-or-less permanent burrows from which they ambush passing prey. Only species in the subfamily Hippasinae build webs. These spiders are thought to possess the most primitive morphological features of the Lycosidae, indicating that they may represent an ancestral lineage. The genus Sosippus builds prey capture webs that exhibit a remarkable resemblance to the funnel-webs of agelenids. The geographic distribution of the 10 described Sosippus species ranges from the southern United States, through Mexico and Central America to Costa Rica. One species, Sosippus placidus, has a very restricted distribution, having been collected primarily at Archbold Biological Station (ABS) and from a few scrub remnants near Lake Placid, Florida. Sosippus floridanus is sympatric with S. placidus, but is distributed across the entire Florida peninsula. We compared the habitat use of these sympatric species at ABS and found that the widespread S. floridanus uses disturbed habitats such as pastures and roadsides, while S. placidus is associated with vegetation specific to scrub. We also describe extended maternal care in which offspring remain in the mother's web past their first molt and feed communally off of prey captured by the mother. This subsocial behavior was observed in S. floridanus, S. placidus, and S. janus. (Added 5 / 17 / 2002)

Basin and Bajada Grassland Spider Communities and the Invasive Grass Eragrostis lehmanniana Nees (Poaceae)
 Author: David Hu and David Richman  Institution: New Mexico State University

 Abstract: Spider grassland communities are diverse and play an important arthropod predator role. Recent invasion by the African grass Lehmann lovegrass (Eragrostis lehmanniana Nees) in the Jornada Basin has influenced the grasslands, by displacing and out-competing the native grasses, such as threeawn (spidergrass) (Aristida spp.), mesa dropseed (Sporobolus brevifolius) and in particular black grama (Bouteloua eriopoda). In this study, we compared two different grassland spider communities (basin and bajada) in which Eragrostis lehmanniana has established and is increasing in dominance. Three Eragrostis lehmanniana treatment levels were selected in each grassland, one of complete dominance, an intermediate level and one of minimal influence. Spiders were collected in hand capture visual surveys and pitfall traps with vegetation associations noted. There were no significant differences found in spider numbers or diversities between Eragrostis lehmanniana treatment levels. The bajada grassland yielded a higher diversity and number of spiders than the basin grassland. There were no significant differences in spider numbers between sample seasons, but a higher diversity of genera was found in the spring samples. Comparisons between levels of Eragrostis lehmanniana influence as well as between grasslands may provide new insight into spider community dynamics and may reveal some of the underlying associations between desert spiders and desert grass species. (Added 4 / 19 / 2002)

 

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J through L

Field observations of the relationships between ecological variables and orb web decorations
 Authors: Michael Justice, Vanessa Lollett
and Brandi Causey
 Institution: Nova Southeastern University
 Abstract: Many species of orb weaver add conspicuous tufts or bands of silk to their webs. Despite a fair amount of theory and some recent testing, the ecological functions of these decorations remain largely debatable. It is likely that the functions vary considerably across individuals, species, and ecological circumstances. With this in mind, a multivariate correlational approach was taken in an attempt to discern which ecological and behavioral variables may be worthy of further study. Field measurements were taken on adult female Argiope aurantia, Argiope florida, Argiope argentata, Gasteracantha cancriformis, and Nephila clavipes. The size of the spider was measured, along with its responsiveness to a 100-Hz tuning fork applied to the web. Web size, height, compass orientation, and angle off vertical were measured, along with the number of Argyrodes, conspecific males, and wrapped prey items present. In Argiope, web decorations were measured by quantifying the geometry of the stabilimentum; specifically, stabilimenta were measured by counting the number of arms, the length of each arm, the angle between arms, and the number of interradial silk crossings. In Gasteracantha, the number of silk tufts was counted and whether they were on radii or frame threads was noted. Many of these variables have never been quantified in the field, so the results provide some baseline natural history data for these species. The relationships between web characteristics and ecological factors provide some limited support for a visual signaling role of these decorations. (Added 5 / 14 / 2002)

Pre-mating isolation among demes of the fishing spider Dolomedes triton : preliminary data.
 Author: Kelly Kissane  Institution: University of Nevada-Reno
 Abstract: Dolomedes triton has the largest range of the North American species, extending from southern Alaska to Mexico. Variations in courtship behavior among the different populations have been documented, though no study has explored whether these variations resulted in reproductive isolation. A preliminary study of three populations in Ohio indicates that the southernmost population (Athens) may be reproductively isolated from the two more centrally located populations (Columbus and Marion). Possible reasons for these observations are discussed. (Added 5 / 3 / 2002)

The systematics of nephiline spiders (Araneae, Tetragnathidae)
 Author: Matjaz Kuntner  Institution: George Washington University and the Smithsonian Institution
 Abstract: Simon's argiopid subfamily Nephilinae consisted of the genera Singotypa, Phonognatha, Deliochus, Nephila (Nephilengys included), Clitaetra, and Herennia. Later, Singafrotypa and Perilla were included in nephilines, and Singotypa was synonymized with Phonognatha. Most earlier authors placed Nephilinae within Araneidae, and recent authors moved it to Tetragnathidae. Hormiga et al. (1995) analyzed a sample of 14 tetragnathid genera, including five nephiline genera. The results supported the monophyly of Tetragnathidae and a clade Nephilinae (Phonognatha (Clitaetra (Nephila (Herennia + Nephilengys))) being sister to all other tetragnathids. No phylogenetic placement has been hypothesized for Singafrotypa, Perilla and Deliochus. This project focuses on a taxonomic revision and systematics of all nephiline spiders. A preliminary phylogenetic analysis of the latest morphological and behavioral data matrix corroborates the monophyly of the following nephiline genera: ((Deliochus + Phonognatha) + (Clitaetra (Nephila (Nephilengys + Herennia)))). However, the support for this nephiline clade is weak. This analysis supports the recent transfer of Singafrotypa and Perilla to the araneid subfamily Araneinae. It does not, however, corroborate the placement of nephilines with tetragnathids. Instead, nephilines are here sister to Araneidae. The implication of the single most parsimonious cladogram is that nephilines are either an araneid subfamily, or alternatively deserve a family status, which conflicts with all recent phylogenetic treatments of araneoids. However, the data matrix is not complete, and most basal araneoid clades are weakly supported in this phylogeny. Eliminating the missing entries, and increasing the number of taxa, will provide a stronger test of the composition and phylogenetic affinities of Nephilinae. (Added 6 / 1 / 2002)

Stabilimentum-associated anti-predator defences of Argiope versicolor
 Authors: Daiqin Li and Lai Mun Kok  Institution: National University of Singapore
 Abstract: Argiope versicolor (Araneae: Araneidae) (Doleschall) is an orb-web spider that often adds conspicuous, white silk designs known as stabilimenta around the hub. The forms of stabilimenta are known to vary with developmental stages. Argiope versicolor juveniles usually decorate the hub with a disc-like stabilimentum, while adult females arrange their silk decorations as a cross. In this study, we investigated stabilimentum-associated anti-predator defence behaviour of A. versicolor both in the field and in the laboratory by addressing three questions: (1) What are the major anti-predator defence behaviours used by A. versicolor? (2) Is there any difference in anti-predator defence behaviour between juveniles and adults? (3) Is an anti-predator defence behaviour stabilimentum-specific? Four major anti-predator defence behaviours were identified for A. versicolor: shuttling, shifting, pumping and dropping. Adults most frequently responded to artificial stimuli with dropping and juveniles with shuttling. Dropping was more frequently initiated than pumping. Disturbance on the leg and abdomen was most likely to elicit a response from juveniles while adult females were more likely to respond to leg disturbance only. No relationship between stabilimentum and sensitivity to specific category of stimulus was found in both juveniles and adults. However, A. versicolor showed stabilimentum-specific anti-predator defence behaviours: juveniles shuttled between sides of the webs with stabilimenta more often than of webs without stabilimenta, while adult females dropped from webs without stabilimenta more frequently than from webs with stabilimenta. Adult females were more likely to pump on the webs with stabilimenta than on the webs without stabilimenta. (Added 5 / 15 / 2002)

Evidence for Interspecific Gene Flow in the Habronattus amicus Species Complex (Araneae, Salticidae)
 Authors: Michael Lowder and Marshal Hedin  Institution: San Diego State University
 Abstract: Gene flow across species boundaries has rarely been documented in spiders, perhaps because the phenomenon is rare, but also because such processes are difficult to detect in nature. Here we present evidence for interspecific gene flow occurring between H. amicus (Peckham & Peckham) and H. cf. signatus, both members of the Habronattus amicus species group. These species are distributed in the western US, where they almost always occur in allopatry. However, we have recently discovered multiple lake basins in the upper Great Basin (southeastern OR, northeastern CA, and western NV) where these species are found together on pluvial sand dunes. Multiple lines of molecular evidence suggest that interspecific gene flow is occurring at some of these sites, perhaps in a unidirectional manner (i.e., H. amicus genes are found in H. cf. signatus, but the reverse is not true). This gene flow is taking place despite obvious morphological and size differences between the taxa, and despite preliminary evidence for fine-scale microhabitat differences. These findings provide novel insights into processes of speciation and character evolution in these jumping spiders. (Added 5 / 15 / 2002)

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M through O

Population divergence under sexual selection in Habronattus pugillis (Salticidae)
Authors and Institutions
 Wayne Maddison  University of Arizona
 Eileen Hebets  University of Arizona
 Susan Masta  San Francisco State University
 Abstract: Montane populations of Habronattus pugillis Griswold in southern Arizona, isolated by intervening desert, show many fixed differences in male courtship characters (ornamentation and behavior). A gene genealogy for mitochondrial DNA was reconstructed, and showed partial but not complete differentiation among the mountain ranges. The shared retention of some polymorphisms in mitochondrial genes contrasts against the fixation of ifferences in the courtship characters, which are presumably under control of nuclear genes. This contrast is statistically significant and points to the courtship divergence being due to selection, given that under a neutral model nuclear genes would be expected to show considerably more polymorphism than mitochondrial genes. To explore the nature of selection on courtship traits, we studied the reaction of females of two mountain ranges (Santa Rita and Atascosa) to their own males and "foreign" males. These two ranges are strikingly different in male traits: Santa Rita males have a brown and white face, and engage in a slow display with palp circling and leg waving, while Atascoca males have a silver face, and have a vigorous sidling display. Atascosa females showed no strong preference, but Santa Rita females accepted the "foreign" Atascosa males significantly more frequently than their own males. This is consistent with the predictions of a model of sexual selection by antagonistic coevolution (e.g. males exploiting female sensory biases and females evolving resistance) but not with those of a model of Fisherian runaway sexual selection.
(Added 5 / 13 / 2002)

Evidence for an ontogenetic shift in retreat structure and placement in the Neotropical tarantula Ephebopus murninus (Araneae: Theraphosidae)
 Authors:Sam Marshall and Rick West  Institution: Hiram College
 Abstract: The theraphosid genus Ephebopus Simon, 1892, currently contains four Neotropical tarantula species which share several unusual traits: they possesses a field of urticating hairs on the prolateral surface of their pedipalpal femora, they are fossorial members of an arboreal subfamily (the Aviculariinae), and they possess spatulate tarsi and metatarsi, traits usually associated with an arboreal lifestyle. We studied the retreat structure and placement of Ephebopus murinus (Walckenaer, 1837) in a forest in French Guiana. We found that early-instar spiderlings construct arboreal retreats in low vegetation, and only shifted to a burrowing lifestyle when well grown. We also studied the placement of the retreats and found that there were no obvious macrohabitat variables that might determine retreat location. We suggest that the fossorial lifestyle of subadult/adult E. murinus has evolved secondarily, and that this might explain the burrow architecture, which is unique among New World theraphosids. (Added 5 / 15 / 2002)

Microhabitat preferences of the scorpion, Centruroides vittatus
 Author: C. Neal McReynolds  Institution: Texas A&M International University
 Abstract: Microhabitat use by Centruroides vittatus (Scorpiones: Buthidae) includes climbing vegetation. This study is to establish if C. vittatus have preferences in the microhabitat selected. The scorpions use of microhabitat did vary significantly at different research sites on the campus of Texas A&M International University in the Tamaulipan Biotic Province. The perennial plants selected by scorpions were compared to the relative abundance of these plant species at the different research sites. The relative abundance of perennial plants varied significantly at different sites with the following species common: blackbrush, Acacia rigidula; desert Christmas cactus, Opuntia leptocauli; prickly pear cactus, Opuntia engelmannii; guajillo, Acacia berlandieri; soapbush, Guaiacum angustifolium; and leatherstem, Jatropha dioica. The plants selected by the scorpions at the different sites were significantly different from the expected frequencies that were based on the relative abundance of plant species. Scorpions did show a preference for some plant species (e.g., blackbrush and strawberry cactus), but their relative abundance did influence the plants selected. Two possible reasons for a microhabitat preference can be higher abundance of prey on some plant species (blackbrush) or as a refuge from predators and high temperatures during the day (strawberry cactus). Future research will establish the effect of prey abundance and microclimate on the microhabitat preferences of C. vittatus. (Added 5 / 15 / 2002)

Spiders collected from mangrove forest in Mexico
 Author: Francisco Medina and Areli Santos  Institution: Universidad Nacional Autónoma
de México
 Abstract: 1582 spiders were collected at 4 localities of a mangrove forest during an expedition to Reserva La Encrucijada in the coast of Chiapas state, Mexico, last April. Spiders were directly collected from mangrove roots, foliage and ground where available, within a 3 hour collecting effort replicated at day and night. Theridiidae was the most abundant family among the web-spinning spiders with 495 specimens collected, while among the wandering spiders, Ctenidae was the most abundant family with 147 specimens. In contrast with the latter, comprised only of two genera with one species each, Theridiidae showed greater diversity with 5 genera and about 6 species identified as of yet. Up to now, 18 other families have been identified out of the whole mangrove sample, including Senoculidae, Dictynidae, Lycosidae, Oxyopidae, Scytodidae, Pisauridae, Corinnidae, Tetragnathidae and Deinopidae. This is considerably more numerous compared with 5 families recorded on the scarce information about this type of ecosystem from other mangrove forests around the world (Australia, Singapore and United States). All the families reported on such references are represented here, with the only exception of one Barychelid from Australia, considered restricted to that zone and in danger of extinction. These data are part of a major study on mangrove spiders of the coast of Chiapas, Mexico. (Added 5 / 16 / 2002)

Representing Behavior: A case study using Habronattus courtship
 Authors: Peter Midford and Wayne Maddison  Institution: University of Arizona
 Abstract: Traditionally, the behavioral repertoire of a species was collected and categorized in a descriptive document called an ethogram. An ethogram is a catalog of terms for behavior patterns with descriptions of those patterns. In the past two decades, the field of computer science called knowledge representation has developed several methods for representing everyday knowledge, such as behavior. The best developed of these methods is the construction of machine "ontologies". An ontology contains a hierarchical set of terms or concepts and a set of relations among them. Terms are "defined" by their relationships with other terms. Ontology-based representations of complex behavior may offer several advantages over conventional ethograms. To illustrate the strengths and weaknesses of each method, we constructed both an ethogram and an ontological representation of courtship behavior in the Salticid Habronattus clypeatus. We then extended the data set to H. californicus. We will present both the ethogram and ontology-based representation of courtship behavior for each species. (Added 5 / 14 / 2002)

Systematics of Neotropical Erigonine Spiders (Araneae: Linyphiidae, Erigoninae): Are We Making Progress?
 Authors: Jeremy Miller and Gustavo Hormiga  Institution: The Smithsonian Institution and
George Washington University
 Abstract: We present a new hypothesis of relationships among erigonine spiders based mainly on morphological characters. We have added taxa and characters to a previous analysis of erigonine relationships by Hormiga (2000). Hormiga encoded 43 taxa including 31 erigonines for 73 characters. We have added 37 erigonine taxa to this matrix. All 80 taxa are coded for 162 informative characters. Most of the characters in Hormiga's analysis are included, sometimes in modified form. Nearly all of the taxa added for the current analysis represent Neotropical genera. We evaluate progress in our effort to understand erigonine phylogeny by studying the impact of new taxa and characters on the relationships hypothesized in the original study. To approach this, we prune all new taxa from the new analysis and identify groups with identical composition in both Hormiga's (2000) original cladogram and the pruned tree based on new characters and taxa. We also reanalyze the original set of taxa using the expanded set of characters. Finally, we use a new method, Continuous Jackknife Function analysis (Miller, in prep.) to assess our progress toward a stable phylogenetic hypothesis. Continuous Jackknife Function analysis uses character removal and a reference hypothesis to evaluate the stability of the hypothesis under test. The results are presented as a graph of the number of clades recovered after character removal and reanalysis against the percent probability of character removal. Stable phylogenies are expected to take the form of a decreasing asymptotic curve with a high rate of clade recovery. (Added 5 / 8 / 2002)

A Comparative Study of Landscape Influences on Spider Migration into Homes
 Author: Carol O'Meara  Institution: Denver Museum of Nature & Science / CSU
 Abstract: During 1999 and 2000, sixty percent of the clients complaining to Colorado State University Cooperative Extension in Boulder County about spiders in their homes claimed that their homes were infested with more spiders than their neighbors living next door. The aim of this study is to determine whether the complexity of landscaping around a home decreases or increases the number of spiders entering the house. To study this, a two-year survey of homes with simple and complex landscapes is being conducted. Urban homeowners make decisions about the extent and type of landscaping they plant around a house and this variation in landscape structure may influence spider migration into homes on a house to house basis. This study includes 20 houses with 5 glue traps each collected on a monthly basis. Overall, 100 traps per month are collected with a total of 2400 traps over the course of this survey. The sampled homes include 10 homes with simple landscapes and 10 homes with complex landscapes. For the purposes of this survey, simple landscapes are those in which up to 30% of the square footage of the plantable property (not covered by buildings) is in herbaceous or woody plantings. The remainder may be covered by turf, mulch, rock, cement, or exposed soil. Complex landscapes have greater than 60% of the plantable area in herbaceous or woody plantings. Fourteen months of data will be discussed, and there appears to be a correlation between complex landscapes and higher numbers of spiders in homes. (Added 5 / 9 / 2002)

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P through R

Spiders of Québec (an identification guide)
 Authors: Pierre Paquin and Nadine Dupérré  Institution: San Diego State University
 Abstract: The spider fauna of the province of Québec actually lists 623 species and the occurence of another 147 is suspected (Paquin et al. 2001). We are here presenting a monograph that will be a major tool for the identification of spiders species of Eastern North America. It includes illustrated keys to families and genera (except Linyphiidae) and genitalias of all species are fully illustrated. We have used comparable angles within each genera to allow an easier recognition of diagnostic characters. The book contains 180 plates (4 species each) presented in a 8.5 x 11 format with a spiral binding to facilitate handling in the lab. Samples of key and plates are given. (Added 5 / 31 / 2002)

Spatial and Temporal Distribution of Sympatric Species of Agelenopsis and Barronopsis
 Author: Marius Pfeiffer  Institution: University of Texas at Arlington
 Abstract: Much work has been done to determine the importance of interspecific competition in moderation of population and distribution of numerous species. Within arachnida recent results have suggested that interspecific competition is not a major ecological force. Additional investigation of natural systems, both passive and manipulative is required for clarification of ambiguities.
A two year survey study was undertaken to determine spatial and temporal distribution of sympatric populations of the genera Agelenopsis and Barronopsis along a road boundary in a riparian habitat. The objective of the study was to determine, indirectly, if the potential for interspecific competition exists between ecologically similar members of closely related genera. Significant overlap of spatial, temporal or substrate use characteristics is considered as suggestive of competitive potential. Significant partitioning of any of these characteristics is considered as indirect evidence for avoidance of competition (Ghost of Competition Past). Ten 5x20m quadrats were surveyed three times per year for the first year and for the spring of 2002. Species, size, 3 axis positional data, substrate and activity were noted for all identifiable animals. Results so far suggest temporal segregation of life histories and spatial segregation among species and based on animal size within species. (Added 5 / 15 / 2002)

Systematics of Island and Mainland Populations of B. californicum
(Araneae, Ctenizidae)
 Authors: Martin Ramirez and Brian Cashin  Institution: Loyola Marymount University
 Abstract: Bothriocyrtum californicum is a large California trapdoor spider. B. californicum samples were collected from six mainland sites in Los Angeles, Orange and San Diego Counties, as well as from Santa Catalina and Santa Cruz Islands, and were assayed for variability at 11 allozyme loci. Estimates of genetic variability for B. californicum are comparable to those of other non-social spiders. A phylogeny for these populations shows that the Otay Mesa population is basal in the phylogeny and the remaining populations are placed in two monophyletic groups: populations of central/northern Los Angeles Co.; and populations from inland Los Angeles Co. to coastal Orange Co. The fact that most populations fall into these two groups may be associated with geologic changes that occurred in this region beginning in the Pliocene. During this time the Los Angeles basin was flooded, which coupled with the northward extension of the Sea of Cortez, severely restricted the movement of organisms to and from Baja California at its northern end until the Pleistocene. This San Gorgonio Barrier has been implicated as a historic biogeographic obstacle for the movements of vertebrate taxa and may be the cause of the evolution of northern and southern mainland groups of B. californicum. (Added 5 / 14 / 2002)

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S through U

The Recluse Community Project: The project designed with the people in mind
 Author: Jamel Sandidge  Institution: University of Kansas
 Abstract: The brown recluse spider Loxosceles reclusa is implicated in medical emergencies in North America each year, leaving many people with open wounds and unsightly scars (necrotic arachnidism), and an intense fear of spiders (loxoscelism). Presently, there are no reliable diagnostic tests to positively identify brown recluse bites. There is no widely distributed antivenom or medically proven treatment, which presents a serious medical dilemma. Controlling infestations has proven to be difficult, and is thought to be impossible. Despite the large number of medical research articles on the components, activity, and destructiveness of Loxosceles reclusa venom, none are devoted directly to exploring the crucial and most essential element of the system -- the spider populations themselves. The Recluse Community Project is a three-year project consisting of four primary areas: public education and awareness, population biology, molecular population genetics, and biological invasion and population monitoring. The immediate and most critical components of this project are to increase our limited knowledge of the behavior, population dynamics and genetics of this clinically significant spider for the benefit of all. These factors may help to reduce the probability of accidental envenomations and associated medical emergencies by providing a clear description of species movements, periods of activity, and patterns of biological invasion. This research is original in that is takes public paranoia, issues of public health and safety, as well as an intense fear of the unknown to solicit public involvement while creating a public fascination for science. (Added 5 / 17 / 2002)

Who preys on the ultimate predator: Life history strategies of the vinegaroon, Mastigoproctus giganteus
 Author: Justin Schmidt  Institution: Southwestern Biological Institute

 Abstract: Vinegaroons, large generalist ambush predators, are often considered curiosities rather than major factors shaping communities. In some areas they likely are the most important predator in the system, and, importantly, prey on large numbers of other top predators including scorpions, sulpugids, and lycosids. Vinegaroons are famous for their defensive capabilities, especially their acid-rich spray. A natural question: if vinegaroons are dominant predators, who preys on them, and what factors are limiting in their life history?

To understand the forces shaping the biology of vinegaroons, prey records from hundreds of hours in the field were analyzed and manipulative laboratory tests were conducted. No vinegaroon of any size or instar was ever observed to be preyed upon in the field and no remnants (pedipalp/leg fragments) were discovered. Laboratory investigations suggest adults die in their overwintering cells rather than being predated. Immatures are rarely seen in the field and might be the vulnerable link in the life cycle. Staged encounters revealed that the defenses of even the first instar free-living immatures are only rarely overcome by predators. Predators most able to endure the acid spray of immatures were large adult lycosids, and carabid beetles and tarantulas. However, even with these predators, success was achieved mainly when the attack was such that the defensive spray was avoided. The results suggest that vinegaroon life history is limited by low reproductive potential, abiotic factors, shortage of food, and some predation on first and second instar individuals by a few species of large spiders or insects. (Added 4 / 18 / 2002)

A Glimpse into the Diversity and Endemism of Malagasy Spiders
 Author: Diana Silva  Institution: California Academy of Sciences
 Abstract: Madagascar is an island in the Indian Ocean separated from Africa since the late Cretaceous, approx. 130 mya. This island, often referred as a "museum of living fossils" for harboring very old phylogenetic lineages, has been the focus of major conservation efforts due to 1) its high levels of endemism for various groups of plants and animals, and 2) the highly threatened status of numerous taxa as a result of deforestation of native habitats and introduced exotic species, among other factors. Through multidisciplinary efforts of various research centers, such as the California Academy of Sciences, a sampling protocol including a wide range of techniques has been designed to document the biodiversity of Madagascar. This report shows the family composition of all spiders recorded from this island after two years of intensive field work, the species richness of the spider communities, and comparisons of the species diversity and distribution patterns of such families as the ctenids (57 spp), gnaphosids (33 spp), lycosids (15 spp), mimetids (12 spp), and sparassids (64 spp). Although available data do not allow comprehensive phylogenetic analyses for most spider families, a cladistic analysis for the Ctenidae suggests that the Malagasy ctenids comprise two lineages; one of them, the viridasines, appear to be the most basal lineage of the family. (Added 5 / 14 / 2002)

A Survey of the terrestrial non-insect macroarthropods of Toft Point Natural Area, Wisconsin
 Authors: Bruce Snyder and Michael Draney  Institution: University of Wisconsin ­ Green Bay
 Abstract: Toft Point Natural Area is a National Natural Landmark owned and managed by the University of Wisconsin ­ Green Bay and is located on the Lake Michigan shore of Wisconsin's Door Peninsula. With twelve different biotic communities on 700 acres, Toft Point is biologically diverse. We attempted a preliminary survey of the terrestrial non-insect macro-arthropods, which include most of the non-aquatic arthropods except insects and mites; specifically, arachnids (spiders and harvestmen), myriapods (centipedes and millipedes), and terrestrial isopods (crustaceans). We sampled on May 2, July 17, and September 22, 2001. One concentrated, spatially integrated litter sample was collected at each of five habitats during each date; these were then Berlese extracted. A timed hand collection was also used, consisting of 0.5 person-hour/site/date, using a combination of techniques, including sweeping herbaceous vegetation, brushing/beating woody vegetation, and hand searching with aspirators within vegetation and at ground level, including turning over rocks and logs.
The 35 samples collected covered nine different habitats. Three of the twelve isopod species known in Wisconsin were found at Toft Point. Five families of myriapods were found, including Polyzoniids rarely found in Wisconsin. 91 species of spiders in 17 families were found, including 60 new to Toft Point, 46 new to Door County, and 10 new Wisconsin state records. These include two southern and two western range extensions. The Polyzoniids and eight of the state records were collected by leaf litter extraction, mostly from wetland habitats. (Added 5 / 7 / 2002)

Molecular Phylogenetic Analysis of North American Grass-spiders (Araneae: Agelenidae)
 Author: Joseph Spagna and Rosemary Gillespie  Institution: U.C. Berkeley
 Abstract: The family Agelenidae (Koch 1837) is large (42 genera, 490 described species) and a number of spiders from this family have been used as models for toxicological and behavioral research. Despite this use, to date little phylogenetic work has been done on these taxa, thus there is little information on the evolutionary context of this research. In the Agelenidae, there are eight genera (Hololena, Rualena, Calilena, Novalena, Agelenopsis, Barronopsis, Tortolena and Melpomene) endemic to North and Central America. Cladistic analysis of molecular sequence data from mitochondrial (cytochrome oxidase 1 and 16S ribosomal DNA) and nuclear (28S rDNA) genes suggests a monophyletic group confined to the Western U.S. (Calilena (Hololena (Novalena + Rualena))), which relates distantly to the more widespread Agelenid genera Agelenopsis and Tegenaria. Preliminary analysis of distributions of subsets of morphological and behavioral characters suggests that while differences between species within each genus is primarily based on genitalic structure, one of the primary differences between the genera appears to be choice of web-substrate. I am using these patterns of character changes to examine ecological and morphological correlates of diversification on temporal and spatial scales. (Added 5 / 16 / 2002)

Response of male Centruroides vittatus to aerial and substrate-borne chemical signals
 Authors: Steffany Steinmetz and Douglas Gaffin  Institution: University of Oklahoma
 Abstract: From insects to primates, chemical signaling aids in the success of mate location. In this study we investigated the possibility that striped scorpions, Centruroides vittatus, use air or ground based chemical cues as a channel of intraspecific communication. A Y-shaped arena was constructed to test scorpions' use of olfactory signals to detect potential mates. A second behavioral choice chamber (similar to that used by previous investigators) was used to test male scorpions' responses to female deposits by direct substrate contact. Male scorpions showed no tendency to move toward females in tests of air-borne chemical transmission. A preliminary test of male response to female deposits suggested some tendency to move to the regions previously occupied by a female. However, subsequent trials showed no bias in male movements relative to potential female deposits. Under the conditions of these laboratory experiments, males did not appear to detect females via air or ground based chemicals. We will repeat this set of experiments during late summer / early fall to test for possible seasonal effects on mate signaling in C. vittatus. (Added 5 / 12 / 2002)

Diagnosis and Therapy of Loxosceles reclusa (brown recluse spider) bites
Authors and Institutions
W. Van Stoecker The Dermatology Center, Rolla, MO
Hernan Gomez University Michigan
Jennifer L. Parks Univ. Missouri-Rolla
 Abstract: Envenomations by North American Loxosceles spiders, most commonly represented by the brown recluse spider L. reclusa, are frequently misdiagnosed. This presentation reviews clinical aspects of envenomations including the typical symptoms, physical findings, and diagnostic tests. Key therapeutic interventions include the RICE regimen and dapsone if the area of necrosis exceeds 1 cm^2 Emerging diagnostic tests include ELISA tests using either polyclonal or monoclonal antibodies. Which clinical features are most important in making the diagnosis of "necrotic arachnidism?" What variants are possible and which findings are more suggestive of clinically similar diagnoses? Very large ulcers, multiple skin lesions, and early ulceration all lead us to alternate diagnoses. This presentation will include brief clinical descriptions of the foremost confounding diagnoses including envenomations by other arthropods, pyoderma gangrenosum and factitial causes of skin necrosis. We will summarize the approximately 90 documented Loxosceles envenomations in North America, a very small number considering the thousands of diagnosis of "spider bites" that are made each year. (Added 5 / 18 / 2002)

Trichobothrial mediation of an escape response: Vertical jumps by Dolomedes triton foil frog attacks
 Authors: Robert B. Suter and Nura Farah  Institution: Vassar College
 Abstract: Jumps of fishing spiders (Dolomedes sp.) from the water surface have been presumed to be evasive behaviors directed against predators. In an earlier study, we analyzed the jumps of fishing spiders and demonstrated that jump heights and durations were inadequate to provide protection against strikes from below by fish. We report here (1) that attacks from the side by large frogs (Ranidae) are effectively evaded by the vertical jumps of the spiders, (2) that leg-borne trichobothria appear to be the primary sensory mediators of the evasive behavior, and (3) that the kinematics of the air just above the water surface can effectively mask the attack of a frog. In a quasi-natural laboratory setting, spiders frequently (in 25 of 30 trials) made no attempt to evade attacks by bullfrogs and green frogs; but when the spiders did attempt evasion by jumping, they escaped uninjured in 4 of 5 trials. When we measured the responses of intact spiders and spiders with disabled trichobothria to sham attacks by a mechanically propelled, freeze-dried bullfrog, we found that the absence of trichobothrial input nearly obliterated the evasion response. Preliminary results indicate that during attacks in which the spiders make no attempt at evasion, the air movements that signal an attack are probably effectively masked by "noisy" ambient air. (Added 4 / 15 / 2002)

New spiders from California (Araneae: Amaurobiidae)
 Author: Darrell Ubick  Institution: California Academy of Sciences
 Abstract: Three new species of spiders are described from California. The first is from the southern Sierra foothills in Tulare County and the other two are from the Mojave region: Granite Mountain (sp 2) and a series of localities from Riverside to Imperial counties (sp 3). All three are small cribellate spiders with similar somatic morphologies and appear related because of synapomorphies of the male genitalia, the most striking of which are an unusual retrolateral furrow on the cymbium and a tripartite RTA. It is argued that the species represent two new genera (1 + (2 + 3)) which are most closely related to Zanomys. This zanomyine complex is defined on the basis of a shared sexual dimorphism (males with a laterally expanded carapace) and is the likely sister group of the subfamily Coelotinae, whose members have a similar retrolateral furrow on the cymbium. The family placement of this clade is not certain as it shows affinities to both the Amaurobiidae and Agelenidae. (Added 5 / 13 / 2002)

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V through X

A comparison of the diversity of ground dwelling spiders in old-growth beech-maple with a second-growth forest
 Authors: Melissa Varrecchia and Maggie Hodge  Institution: Hiram College
 Abstract: Beech-maple forests were once widespread throughout Ohio and Indiana, but are now restricted to a few small remnant sites. We report on preliminary findings of a study designed to measure and compare species turn-over rates in a pristine 200 acre beech-maple forest and an adjacent, second growth forest at the J.H. Barrow Field Station in northeast Ohio. Eight pairs of pitfall traps were sampled in each habitat at weekly intervals from May-August 2001. Abundance, familial and generic diversity as well as various phenological patterns will be presented. (Added 5 / 22 / 2002)

Title: The myth of the brown recluse spider: myth-takes, myth-identifications and myth-diagnoses
 Author: Rick Vetter  Institution: University of California at Riverside
 Abstract: The brown recluse spider, Loxosceles reclusa, is rarely found outside of its endemic range (southeastern Nebraska to southernmost Ohio, south to Texas and Georgia). Despite the fact that brown recluses are extremely rare in non-endemic areas, the general public and the medical community believe that the spider is common throughout the United States and is the cause of mysterious wounds of unknown etiology. The annual number of medical diagnoses of brown recluse bites in many non-endemic states or regions is tens to hundreds times greater than the historic total of verified brown recluses from the area. In endemic areas, individual homes can be infested annually with more brown recluses than can historically be documented in several American states and often, no one from these Midwestern homes shows evidence of a bite. The myth of the brown recluse is kept alive by medical misdiagnoses, misidentifications of harmless common spiders, hyperbolic news media and erroneous public perception. The danger lies in that because the diagnosis of "brown recluse spider bite" is so readily accepted by both the medical community and their patients in non-endemic areas, these misdiagnoses mask a plethora of medical maladies which manifest themselves in dermatologic eruptions. Although many of these maladies are innocuous with no long-term effects, several conditions (such as Lyme disease, anthrax, necrotizing bacteria, lymphoma, leukemia) can be debilitating or fatal if the ailment is misdiagnosed and remedy is delayed or incorrect. (Added 3 / 17 / 2002)

The distribution of the hobo spider, Tegenaria agrestis, in the United States and Canada
Authors and Institutions
 Richard S. Vetter  University of California, Riverside
 Alan H. Roe  Utah State University, Logan
 Robert G. Bennett  British Columbia Ministry of Forests, Saanichton
 Craig R. Baird  University of Idaho, Parma
 Lynn A. Royce  Oregon State University, Corvallis
 William T. Lanier  Montana State University, Bozeman
 Arthur L. Antonelli  Washington State University, Puyallup
 Paula E. Cushing  Denver Museum of Nature and Science, Denver CO
 Abstract: Since the late 1980s, the hobo spider has been implicated in necrotic wounds in the northwestern United States and British Columbia, Canada. Before this, necrotic wounds were blamed on the brown recluse spider even though there were no recluse populations there. Because it is a spider and because it is blamed for causing wounds, the hobo spider is the subject of much hyperbole. Sources of information are usually regional in scope or come from non-arachnologists, hence they are subject to misintrepretation and exaggeration. Along with 7 collaborators, I coordinated a study to determine where the hobo spider is found. The current known range is from southern British Columbia to southern Oregon and eastward to central Montana, western Wyoming and northern Utah. All of Washington and Idaho are considered within the range of the hobo spider. There are two reliable isolated populations associated with two houses in Colorado. This study also mapped out the distribution of the giant house spider, Tegenaria duellica (synonymizations include T. saeva and T. gigantea) which is found on the Pacific side of the mountains in British Columbia, Washington and Oregon, is more common than the hobo spider in most human population centers where the two species are found, is considered harmless but is often misidentified as a hobo spider by non-arachnologists. (Added 5 / 10 / 2002)

Observations on courtship, mating, maternal care and subsocial behavior of the East African tarantula Heterothele villosela (Araneae: Theraphosidae)
 Author: Amanda Weigand, Barbara Vasquez and Sam Marshall  Institution: Hiram College
 Abstract: Spider sociality is a rare phenomenon, being observed in less than 0.1% of described species. We studied the reproductive behavior, maternal care, and spiderling social behavior of Heterothele villosela Strand, 1907, a small theraphosid in the subfamily Ischnocolinae from East Africa. This genus is phylogenetically enigmatic, having been recently moved between different genera and even families. The current hypothesized placement of this genus places it in a poorly-defined group of small and widely distributed tarantula species. Ours will be the second description of the sociality in Heterothele, and one of the few studies of the social behavior any tarantula. We acquired 32 H. villosela collected in Tanzania from a commercial importer. The spiders were held in 1.0 liter plastic containers with a bark mulch substratum, a piece of bark for a refuge, and a small water dish. The spiders are fed twice weekly on domestic crickets. The cages were held in a humidified, heated room (27oC and 20% rh) with ambient sunlight for photoperiod. We paired spiders and videotaped the courtship and/or matings. We generated ethograms of the behaviors observed and compared successful to unsuccessful courtships. We also observed the interactions of the females and offspring. (Added 5 / 15 / 2002)

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Y and Z

ITS2 rDNA variation of two black widow species, Latrodectus mactans and Latrodectus hesperus
 Authors:Daiyuan Zhang, Bill Cook, and Norman Homer  Institution: Midwestern State University
 Abstract: The taxonomic status of two closely related species of Latrodectus, L. mactans and L. hesperus, has been debated for many years. Based on morphological characteristics and genitallia, some workers consider them valid species and others as subspecies. The purpose of this project was to determine whether the internal transcribed spacers 2 (ITS2) of rDNA from the two taxa exhibit sequence differences which could shed light on their taxonomic relationship.
Individuals of Latrodectus mactans and Latrodectus hesperus from six populations were collected and identified based on reported morphological characteristics. The ITS2 rDNA of 9 individuals were sequenced and analyzed. Results suggest that: 1) ITS2 sequences in the two taxa exhibit minimal differences. 2) The assignment of the two taxa to seperate species is not supported by ITS2 sequences comparison. (Added 5 / 8 / 2002)

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