Abstracts

Thirty-Second Annual Meeting of the American Arachnological Society

Hosted by:

Rosemary Gillespie & Charles Griswold

Updated May 9, 2008

at the

The University of California at Berkeley

ABSTRACT DEADLINE FOR RECEIPT: SATURDAY JUNE 7

Taxonomy and phylogeny of the Tegenaria-Malthonica complex (Araneae, Agelenidae) using morphological and molecular data – preliminary results

Angelo Bolzern

Naturhistorisches Museum Basel
Department Life Sciences, Basel, Switzerland

Naturhistorisches Museum Basel
Department Life Sciences, Basel, Switzerland

Abstract: Malthonica Simon and Tegenaria Latreille represent two species-rich genera of the family Agelenidae. They are predominantly Palaearctic in distribution. Currently 41 species and one subspecies are described in Malthonica and 101 species in Tegenaria, respectively. The group is notorious for its taxonomic problems: lack of diagnoses of the two genera, arbitrary generic assignement of species, availability of information for only one sex in many species, unknown internal phylogenetic relationships and presence in collections of additional undescribed species. Recently, several Tegenaria species were transferred to Malthonica, based on the embolus length, a character which is on its own not sufficient for phylogenetic reconstructions. An additional problem: Tegenaria agrestis, a species native to Europe and introduced into the USA, where it is blamed for biting humans and causing serious wounds followed by necrosis. In Europe, no such case is known. The question of conspecifity of the American and European populations can be answered as a by-product of the revision of the European Tegenaria-Malthonica complex. The phylogenetic relationships within the complex will be analysed using morphological and molecular methods. The following aspects are presented: 1) potentially useful morphological characters for delimiting the genera, 2) some taxonomical results and 3) preliminary molecular analyses. posted 30 April 2008

Cytochrome oxidase I variation in agroecosystem linyphiids and lycosids

Matthew H. Greenstone

Invasive Insect Biocontrol & Behavior Laboratory
Agricultural Research Service, Beltsville, Maryland, USA

Department of Biology, University of Mississippi
Oxford, Mississippi, USA

Smithsonian Institution
National Museum of Natural History, Washington, District of Columbia, USA

Department of Entomology, University of Maryland
College Park, Maryland, USA

Abstract: Cytochrome Oxidase I (COI) is the most-used DNA barcoding sequence for animals, but little is known about its intra-specific variability in spiders. We present haplotype frequency data for five common agroecosystem linyphiids and lycosids. Variation is high in Florinda coccinea, Meioneta unimaculata, and Tennesseellum formicum, low in Pardosa milvina, and intermediate in Rabidosa rabida. Considering spider phylogenetic constraints and population size, crop physiognomy, and agronomic practices, we present hypotheses to explain these differences. The levels of variation observed are not likely to diminish the usefulness of COI for barcoding spiders; comparisons with congeners are needed to resolve this question. posted 17 April 2008

Differences in male and female foraging:  Giant females play the lottery

Linden Higgins

Department of Biology, University of Vermont
Burlington, Vermont USA

Abstract: Spiders in the orb-weaving genus Nephila  are famous for their extreme sexual size dimorphism, which is due primarily to differences in the number of juvenile instars.   In addition, female N. clavipes show large amounts of variation in size and timing at maturity that is believed due primarily to differences in the number of juvenile instars.  To test this hypothesis, I reared spiders from eggs laid by females collected in several Mexican populations and one Texan population.  Spiderlings were randomly assigned to one of three different diets spanning the range observed in the field and reared to sexual maturity.  The rearing experiment showed several unexpected patterns.  First, there were sexual differences presumably related to small male size:  males from all populations were capable of reaching maturity on any diet, but only females from Texas could regularly reach maturity on the low or medium diets.  Second, female nutritional needs increased dramatically following the sixth molt.  Third, even on the highest diet, developmental rates slowed dramatically in the seventh and eighth instars.  I hypothesize that this may reflect the existence of a lottery-style life-history, where females are dependent upon the rare capture of large packages of resources in order to successfully reach maturity. posted 24 April 2008

The goblin spider genus Scaphiella (Araneae, Oonopidae)

Norman I. Platnick

Division of Invertebrate Zoology
American Museum of Natural History
New York, New York USA

Abstract: Currently 23 species are placed in the goblin spider genus Scaphiella, but two of those species (S. maculata Birabén 1955 from Argentina, and S. ula Suman 1965 from Hawaii) are misplaced in the genus and belong elsewhere.  Aside from those misplacements, the monophyly of the group is supported by at least two characters.  First, the ventral abdominal scutum of females is greatly enlarged, extending completely up the sides of the abdomen to the dorsal surface, so that the abdomen looks like a taco shell.  Second, the female epigastric region is uniquely modified, with circular, epigynum-like external modifications.  The genus occurs from California, Utah, Texas, and southern Florida south to Chile and Argentina, and is significantly more speciose and diverse than previously recognized.  We hypothesize that the genus consists of two quite different species groups, which vary in cheliceral, female palpal, and male palpal characters.  As with other oonopids, many highly peculiar features occur within the genus.  Some species have characteristically asymmetrical male palps, with the right palp being uniformly reduced relative to the left one.  Other species have lost the posterior median pair of spinnerets, and seemingly have no cylindrical silk glands.  Two new species, from Mexico and Colombia, are oddly enlarged and, at 3.3 mm, may be the world’s largest oonopids. posted 9 May 2008

Male Dolomedes scriptus (Hentz) (Araneae: Pisauridae) detect female mating status by chemical cues in silk

School of Sciences
Lynchburg College
Lynchburg, VA USA

Kari E. Benson

Abstract: Communication has been widely studied in many taxa, particularly in the context of mating search strategies and assessment.  Males of many species assess reproductive status or receptivity via a number of cues to enhance courtship decisions.  Females of many spider species are known to embed pheromones in their silk.  Depending on the species, these chemical cues can be found in web-bound or dragline silk and can convey crucial information about the female.  We tested male response to female chemicals in the fishing spider, Dolomedes scriptus.  In a closely related species, D. triton, previously mated females often exhibit cannibalism of males. The risk of cannibalism makes poor courtship decisions in this species particularly costly.  To determine whether male D. scriptus can detect female mating status by chemical cues deposited in dragline silk, males were randomly exposed to female-deposited silk within a female’s container.  In the first part of the test, the female was absent; the female was subsequently returned to her container.  Males performed more overall overt courtship behavior in the presence of silk from virgins than in the presence of silk from either mated or penultimate females.  Male mating behavior and male ability to discern female mating status are particularly important in this potentially cannibalistic species.  The adaptive value to females of signaling their mating status is unclear and needs further investigation. posted 9 May 2008

The first fossil Mecysmaucheniidae from Lower Cretaceous (Upper Albian) amber of Charente-Maritime, France

Erin E. Saupe

University of Kansas, Paleontological Institute
Lawrence, Kansas USA

Abstract: The first known fossil mecysmaucheniid spider is described from Lower Cretaceous (Upper Albian) amber of Charente-Maritime, France. This is the first fossil spider to be formally described from French Cretaceous amber and extends the geological record of Mecysmaucheniidae back into the Cretaceous, the family having previously been known only from the Recent. The fossil differs from other Mecysmaucheniidae in having four, rather than two spinnerets, so it can be considered plesiomorphic with respect to modern members of the family in this character. The amber of the Archingeay-Les Nouillers area is uniquely considered a litter fauna, and our specimen corroborates this hypothesis. Sister group to mecysmaucheniids, the Archaeidae, and now the Mecysmaucheniidae, have been found as fossils only in the northern hemisphere, yet their Recent distributions are entirely southern hemisphere (Gondwanan). The find suggests a former pancontinental distribution of Mecysmaucheniidae, thus supporting the theory of ousted relics. posted 19 April 2008

The distribution of the brown recluse spider, Loxosceles reclusa (Araneae: Sicariidae) in Georgia

Richard S. Vetter

Department of Entomology, University of California
Riverside, California USA

Department of Entomology, University of Georgia
Athens, Georgia USA

Georgia Experiment Station, University of Georgia
Griffin, Georgia USA

Abstract: Georgia is on the southeastern margin of the native range of the brown recluse spider, Loxosceles reclusa Gertsch and Mulaik. The brown recluse is not a common Georgia spider, being submitted only rarely and is not widespread throughout the state. Using recent submissions and previously published records, we document the spider’s presence in only 29 of Georgia’s 159 counties, with almost all being found in the northern portion. If its occurrence is accurately portrayed by the data, then the spider’s range includes the geologic provinces of the Ridge and Valley, the Blue Ridge and the Piedmont, all north of the dividing Fall Line with only two finds of specimens in the southern Coastal Plain province. There were two finds of the non-native world tramp species, L. rufescens, both found south of the Fall Line and are considered transported specimens. A 5-yr Georgia poison control database shows reports of Loxosceles spider bites throughout the state (from 64.8% of its counties) greatly outnumbering the verifications of brown recluse spiders.  Unless additional research can uncover the existence of this spider in the southern half of Georgia, medical diagnoses of brown recluse spider bites there have virtually zero probability of being correct.  Bite diagnoses should be made with caution in northern Georgia given the spider’s sporadic distribution with low frequency of occurrence. posted 3 April 2008

Phylogeny and biogeography of the subfamily Euophryinae (Araneae: Salticidae)

Junxia Zhang

Department of Zoology
University of British Columbia
Vancouver, BC, Canada

Abstract: As one of the largest subfamilies of jumping spiders (Salticidae), the Euophryinae currently contains at least 95 genera and more than 800 species. Its systematics is currently messy, and delimitations of many genera are not clear. Euophryinae is the only major group of jumping spiders to have diversified into many genera in both the Old and New World, which makes its historical biogeography particularly interesting. This project aims to clarify the phylogeny of the subfamily and its placement in jumping spider phylogeny. Five genes (mitochondrial DNA: COI, 16SrDNA, NADH1; nuclear DNA: 28S rDNA, Actin) were amplified and sequenced. 119 euophryine species (97 identified species of 42 genera and 22 unidentified species) and 35 outgroups are included in the phylogenetic analysis. The result strongly supports the monophyly of euophryines and confirms close relationships of some euophryine genera proposed by morphological studies, for instance, Cobanus and Sidusa. Mapping distribution on the phylogenetic tree shows that most euophryines from the New World are more closely related to each other than to those from the Old World, vice versa. This finding is consistent with other analyses that suggest much of salticid diversification occurred after the separation of the continents of the Old World and New World. posted 9 May 2008