The effects of exposure to a single sublethal dose of the pesticide malathion on the courtship and mating behavior of the lycosid, Rabidosa rabida (Walckenaer 1837) is explored. Animals were tested in combinations where one or both sexes were exposed to the insecticide. The data indicate that while there was no effect on the patterning of courtship behavior, control males initiated courtship more rapidly than dosed animals. Mating behavior was severely disrupted and resulted in most dosed males being killed by females without achieving copulation.

Thirty-two species of pseudoscorpions have been found co-existing with nine packrat (or woodrat) species of the genus Neotoma, and this association has been referred to as phoresy. Phoresy is a term for passive dispersal when an animal literally hitches a ride on another to reach a new habitat. The pseudoscorpions reported above live in or on the nests of the packrats and do not ride on the rats themselves, eliminating a truly phoretic association. All life-history stages of the small arachnids have been found in packrat nests, indicating at least a commensalistic relationship exists, whereby the pseudoscorpion benefits from shelter and food found in the nests, and reproduces there as well. Two pseudoscorpion species have been reported feeding on packrat ectoparasites, specifically larval and adult fleas, and thus a mutualistic relationship beneficial to both “guest” and “host” exists.

A checklist of North American solifugae is presented along with their type localities, location of types, known numbers of specimens of each sex collected and the biomic distribution of each species. One hundred ninety-six solifugid species have been recorded in mainland North America, mostly from the United States. Forty-eight species are known from types only. Fifty-five species are known from males only and twenty-four are known from females only. The large hot deserts, Chihuahua and Sonora, contain the majority of collected solifugid species.

A new species of Cyphophthalmi (Opiliones) belonging to the Sri Lankan genus Pettalus is described and illustrated. Characterization of male and female genitalia and SEM illustrations are included, representing the first such analysis for the genus. This constitutes the first species of Pettalus to be described since 1897, although information on other morphospecies recently collected in Sri Lanka indicates that the number of species on the island is much higher than previously thought. The presence of eyes in pettalids is illustrated for the first time and the implications of the presence of eyes outside of Stylocellidae are discussed.

Tissues of lycosid spiders were studied for RNA distributions with the basic dye Azure B. Changes in the basic proteins associated with DNA during spermiogenesis were identified with alkaline fast green staining after DNA extraction with trichloroacetic acid and by cytochemical tests for arginine. Tissue glycoproteins of the gut diverticula and the ducts of silk glands were resistant to diastase digestion and required periodic acid hydrolysis to localize reaction products with the Schiff reagent for aldehydes. Spiders possess novel types of cells that are in need of further study and may be useful as models for developmental biology.

When forced by prodding to run continuously, Centruroides hentzi (Banks 1901) (Scorpiones, Buthidae) lost over 70% of initial speed within 30 s and moved fitfully, if at all, after 90 s. A lack of behavioral response to alternative stimuli presented after two mins of prodding suggested that the scorpions were physiologically fatigued. Mean whole body D-(-)-lactate concentration increased from resting values of 0.6 μmol/g to 4 μmol/g at exhaustion, an approximately 6.5-fold change. It is unlikely that scorpions accumulate significant amounts of other anaerobic products. Whole body lactate accumulations in C. hentzi are lower than those found in species of spiders, crabs and terrestrial ectothermic vertebrates that are more specialized for running. This difference may be the result of proportionately more non-locomotory body mass in the bodies of scorpions compared to these other animals and not due to lower rates of anaerobic metabolism within locomotory muscles.

This study revises the status of crab spiders (Araneae, Thomisidae) endemic to the Society Islands, a volcanic archipelago situated in the southern Pacific Ocean. Only one species, Misumenops melloleitaoi Berland 1934, known from a single female and immature, was previously recorded from Tahiti (the largest island of the Society archipelago). Field surveys (1999–2003) and examination of material in natural history collections show that thomisid spiders occur in four islands of the Society archipelago and are recognized as two endemic species. Misumenops temihana is described as new from the islands of Raiatea and Huahine. This paper further presents the first description of the male of M. melloleitaoi Berland 1934, and extends the range of this species to include multiple localities on the islands of Tahiti and Moorea. Misumenops melloleitaoi can be easily distinguished from M. temihana by the presence of two short black lines on the ventral surface of femur and patella I and II which are lacking in M. temihana.

Spiders have long been noted as classic examples of extreme sexual dimorphism and adaptations to the lifestyle of a sit-and-wait predator. We examined sex-based differences in the metabolic rate of two species of wolf spider that differ in their degree of sexual dimorphism and predatory strategy. Pardosa milvina (Hentz 1877) is a small active wolf spider that does not exhibit a large degree of sexual dimorphism in body size. Hogna helluo (Walckenaer 1837) is a large, strongly sexually dimorphic wolf spider with large, sedentary females and smaller, active males. We found that P. milvina had a higher mass-specific metabolic rate than H. helluo. Also, P. milvina males had a higher metabolic rate than P. milvina females but there was no difference in mass-specific metabolic rate between H. helluo males and females. Our data demonstrate that an actively foraging species, P. milvina, exhibits a higher metabolic rate than species with a sit-and-wait strategy, H. helluo. This suggests that activity levels may be correlated with metabolic rates. In addition, we hypothesize that sexual selection and selection for specific reproductive roles may have resulted in species differences in sexual dimorphism for metabolic rate.

When there are direct conflicts in resource allocation to foraging effort versus growth and development, the relative allocation to foraging may change in a predictable manner with development. Orb-webs provide a physical record of resource allocation to foraging, and their synthesis requires the investment of physiologically important resources. Spiders in strongly seasonal habitats must complete development prior to the end of the season, and may be expected to alter foraging effort to maximize the probability of successful reproduction. Comparison of populations of the orb-weaving spider Nephila clavipes (Araneae, Nephilidae) in very seasonal versus less seasonal habitats allows testing for changes in allocation of resources to foraging effort during development. Orb-web size increases with increasing spider size, with little variation in slope among populations. However, in univoltine populations inhabiting strongly seasonal habitats, the size of the orb web is not a simple function of spider size: the rate of increase in orb-web size decelerates abruptly at a relatively small juvenile stage. Spiders in a less seasonal habitat did not decelerate foraging investment, and the pattern cannot be explained by changes in other aspects of orb-web structure. I postulate that the decline in relative investment into foraging is related to increased investment into juvenile female growth and development in circumstances where delayed maturation carries heavy fitness penalties.

Glenognatha emertoni (Simon 1887) is a small haplogyne orb-weaver collected near streams and dry streambeds in southern Arizona whose habits are unknown. Field observations revealed that G. emertoni are commonly found in vegetation overhanging streams and, more rarely, under streamside rocks. Mating pairs were observed on or near adult female webs. Males lack mate-guarding behavior and leave the female immediately after copulation. To examine mating behavior in a controlled setting, juveniles and adults were collected from the field and maintained in the lab. Matings were arranged between wild-caught adults and also between laboratory-reared virgins in order to describe mating behavior and sperm release during copulation. Unlike most other orb-weaving spiders studied, the number of sperm released and overall duration of copulation are not influenced by female mating history in G. emertoni. Male G. emertoni release equivalent numbers of sperm to virgin and non-virgin females. Given this pattern of sperm release and the lack of mate-guarding behavior by males, sperm competition should be intense in this species. Based only on the numbers of sperm released by each male in the study, doubly-mated females would be expected to produce egg sacs of mixed paternity, if all else were equal.

Aggregation, extended mother-offspring-sibling interactions, and complex social behaviors are extremely rare among arachnids. We report and quantify for the first time in Amblypygi prolonged mother-offspring-sibling associations, active aggregation, and frequent “amicable” (tolerant, nonaggressive) tactile interactions in two species: Phrynus marginemaculatus C.L. Koch 1840 (Phrynidae) and Damon diadema (Simon, 1876) (Phrynichidae). Sociality is characterized by frequent contact and tolerance, and infrequent agonism until sexual maturity in D. diadema and into adulthood in P. marginemaculatus. We experimentally examined potential benefits and costs affecting aggregation: risk of predation, preferred habitats and prey availability. Only increased predation risk decreased nearest-neighbor distances and increased maternal vigilance. Individuals aggregated on a variety of surface textures and locations that varied daily, rather than aggregating only on preferred microhabitats. Manipulation of prey abundance had no affect on the tendency to aggregate.

Patterns of parental care, duration of association, and the presence of social traits found in the most social taxa of non-spider arachnids are reviewed. Species in most arachnid orders have transient parental care with defense of eggs, a brief period of association with newly emerged young prior to independent foraging and explosive dispersal from the natal nest. More prolonged sociality, with long-term associations among mothers-offspring-siblings is rare and is only described in a few species in the Amblypygi, Scorpionida, Pseudoscorpionida, and Acari. All such species have subsocial origins, but current use of the term subsocial is overly broad and we propose a more restricted terminology for clarity.

The prey of the lynx spider, Oxyopes globifer Simon 1876, occurring on Salsola nodulosa (Moq.) plants, was analyzed. In common with other cursorial spiders, the percentage of feeding specimens in the population of O. globifer was low (5.5%). Males were observed feeding significantly less frequently than females and immatures of both sexes. After oviposition, however, the records of prey capture in egg-guarding females also declined considerably. Oxyopes globifer is a polyphagous predator feeding on a wide range of arthropods: insects of the orders Hymenoptera, Diptera, Lepidoptera and Homoptera, as well as on several spider species. The primary food was worker ants, which accounted for 62.7% of total prey. No other prey taxon was present in any considerable percentage. O. globifer captured prey ranging between 22.7 and 243.8% (mean 88.8%) of its own body length. Most frequently taken were medium-sized arthropods varying from 50–110% of spiders' body lengths.

Orb-webs constructed by members of the spider family Araneidae are composed of sticky and non-sticky threads deposited in a stereotypic fashion. This study examines how changes in a spider's nutritional condition affect the capture thread properties and architectural details of its web. It does so by characterizing the features of successive webs constructed by unfed spiders that were not allowed to recycle previous webs. The volume of a capture thread's viscous material and the threads' inferred stickiness decreases in successive webs, although the capture thread's extensibility does not change. The lengths of both capture thread and non-sticky thread decrease at similar rates in successive webs. The decreasing stickiness of capture threads reduces the stickiness per unit capture area. We did not detect asymmetry in the spacing of either spiral or radial threads of first and last webs, nor did we observe differences in the sizes of viscous droplets in outer and inner spiral turns. This suggested that these spiders assessed their silk resources before they initiated web construction and altered their behavior to produce a highly regular web of an appropriate size for their silk reserves.

Currently, 60 species of harvestmen have been karyotyped and all of these are from the Nearctic and Palearctic regions. This work is the first cytogenetic report of three gonyleptid species of the suborder Laniatores: Goniosoma aff. badium, G. proximum and G. spelaeum of the Neotropical region, from the southeastern region of Brazil. Conventional Giemsa stain chromosome preparations were obtained from embryonic cells and adult male testes. Embryo mitotic plates of G. aff. badium and G. proximum indicated 88 chromosomes, and mitotic spermatogonial plates of G. spelaeum males revealed intra- and interindividual variation of chromosome number, ranging from 92–109 chromosomes. In the three analyzed species, the mitotic chromosomes were meta- or submetacentric with no obvious sex chromosomes being identified during mitosis. Prophase I spermatocytes of G. spelaeum also revealed intra- and interindividual bivalent number variation and furthermore indicated the presence of multivalence. The karyotypes of these three Goniosoma species exhibited the largest chromosome pair with a negative heteropycnosis in the distal region of the shortest arm; chromosomes of G. spelaeum submitted to silver impregnation evidenced this negative heteropycnotic region as nucleolus organizer region (NOR). These results, when compared with cytogenetic data of other Laniatores species from the Palearctic region, indicated that a new record for diploid chromosome number probably characterize the genus Goniosoma in the Neotropical region.

Nephila ?hirta Taczanowski 1873 was described from French Guiana, but is currently listed under Nephilengys L. Koch. It is here redescribed and transferred from Nephilinae (Tetragnathidae)* to the araneid genus Eustala Simon, and proposed as a junior synonym of E. fuscovittata (Keyserling 1864). Eustala appears to be the most speciose American araneid genus and is in need of revision.

We tested three hypotheses concerning the function of stabilimenta in the orb weaver Gasteracantha cancriformis: 1) warning to large animals that might accidentally destroy the web; 2) prey attraction; and 3) camouflage. One prediction of the warning hypothesis (but not of the others), that less exposed webs should have fewer stabilimentum tufts, was verified: very few tufts occurred on the peripheral lines of small webs. On the other hand, a prediction of the prey attraction hypothesis, that webs with more stabilimentum tufts should also have more captured prey, was only confirmed in one sub sample, and further analysis indicated that spider size rather than number of stabilimentum tufts best explained the presence of prey. An additional observation not in accord with prey attraction was that resting webs, which lacked sticky silk for prey capture, nevertheless had abundant stabilimentum tufts. Finally, the number of stabilimentum tufts was lower in the webs of white (as opposed to yellow or orange) spiders, contradicting a prediction of the camouflage hypothesis. The strongest conclusions from our results are support for the warning function, and lack of support for the prey attraction function.

The attack behavior of the cobweb spider Achaearanea tesselata (Keyserling 1884) is roughly separated into three sequential steps: descend from the suspended retreat, pass through the sheet threads, and wrap the prey from underneath the sheet. The position and speed as the spider descended varied apparently according to prey type. In the fastest descent, A. tesselata fell free upside down, with all legs free and stretched upward. Two other relatively slow types of descent occurred when spiders approached the sheet head down or climbing down on a mesh thread. The behavior used to pass between the sheet lines showed little variation. It occurred at high speed with the legs folded dorsally; when the legs were in this position the spider offered a very small area of impact, apparently permitting the femora to penetrate or open a space between the lines of the sheet. The spider then opened the femora of the legs to create enough space for the cephalothorax, and seizing the sheet from underneath with legs I, II, and III, the spider pulled the abdomen and hind legs through the sheet. Then the spider rushed to the prey, flung viscid lines at the prey, and wrapped it. Attacks occurred in as little as 0.11 s after the spider began its descent. The design of the webs of A. tesselata transmits information regarding the location of the prey trapped on the sheet to reach the resting spider inside the retreat. The first response of the spider in her retreat was to turn to face the prey; the spider then climbed down along mesh threads following a nearly straight line to the prey.

The genus Waitkera is the only New Zealand representative of the family Uloboridae and is known from a single species, Waitkera waitakerensis. This species is found in forests of the North Island, where it constructs orb-webs on understory vegetation. Rock outcrops in the Northland region support populations of W. waitkerensis comprised of larger individuals than those found elsewhere on the island, including those in surrounding forests. Parsimony analyses of DNA sequences from the mitochondrial NADH dehydrogenase subunit ND1, using Siratoba refernes, another basal uloborid, as an outgroup, did not delineate these rock-dwelling populations as a monophyletic lineage that could be regarded as a distinct species. A TCS analysis leads to the same conclusion, suggesting that rock-dwelling populations represent independently evolved ecotypes. Northland populations of W. waitakerensis are phylogenetically basal; indicating that the species' range contracted northward during the Pleistocene and recolonized the remainder of the North Island.

In this note, I describe courtship and mating behavior of the wolf spider Rabidosa santrita (Chamberlin & Ivie 1942) from riparian habitat in southeastern Arizona. Males responded to substrate-borne cues of females with several distinctive behaviors: they walked slowly, following female web draglines; with their palps, they plucked the dragline and/or tapped on the substrate near the dragline; and they performed raises and extensions of legs I, “tapping” the tips while in midair. On substrate previously occupied by another male, these behaviors were either not done or males performed them more rapidly, and for a shorter duration. Males initiated courtship, which consisted of taps or short strokes of legs I of the female by the male's legs I. Copulation was similar to that described for other species of Rabidosa. Males inserted one palp at a time, performed one hematodochal expansion per insertion, moistened the palp following insertion, and alternated palps for each insertion. Copulation lasted from 35 min to >1 h.

We describe the presence and dimensions of viscid globules in both the sheet and tangle portions of the webs of Achaearanea tesselata (Keyserling 1884). We found viscid globules in all sheets and tangles of the webs examined. The globules were very small and water soluble. The globules were present in the sheet of the first web built by a juvenile (n = 1), but their density was lower than in webs of mature females (n = 6).

A population of Myrmarachne formicaria has been discovered in northeastern Ohio. There is reason to believe that this species, which is widespread in Europe, is a recent accidental introduction to this area. This species seems to be well established, having been found with increasing frequency over the past three years. The species appears to be common in a variety of situations, including occasionally inside buildings.

We examined the prey caught in L. intermedia webs in one fragment of forest and in the garage of an urban house in Curitiba, Brazil. A total of 693 prey items was recorded in 131 webs. The prey richness was greater in the forest. The results show that L. intermedia is a dietary generalist. We found remains of L. intermedia in the feces of a frog and a bat in the forest.

A new species of hackled mesh spider, Platocoelotes polyptychus (Araneae, Amaurobiidae), is described and illustrated based on specimens from Gufengdong Cave, Hunan Province, China.

We recorded the number of ectoparasitic erythraeid mite larvae (Leptus sp. Latreille 1796) that were attached to 1241 Leiobunum formosum Wood 1870 from a population in southeastern Virginia. The prevalence of infestation (percent of individuals parasitized) exhibited significant annual and seasonal variation, ranging from 0.5% to 20.3%. The mean intensity of infestation (number of mites per parasitized individual) varied from 1.0 to 1.3, with a maximum observed intensity of 3 mites/individual. This study provides the first description of annual and seasonal variation in mite infestation of harvestmen.

The first known males of the spider Plectreurys arida Gertsch are described from the xeric shrub habitats and houses of Baja California Sur, México. Males have a smaller carapace and abdomen than females. The length and spination formula of the first leg differ from females; the first legs are longer, and the chelicerae have stridulating grooves in males.