This study reports on the pseudoscorpion fauna of the subterranean ecosystems of northern Arizona, U.S.A. Our work resulted in the descriptions of two new species, Hesperochernes bradybaughi sp. nov. and Tuberochernes cohni sp. nov. (Chernetidae) and the range expansion of one species, Larca cavicola (Muchmore 1981) (Larcidae). All of these species were cave-adapted and found within caves on Grand Canyon-Parashant National Monument in northwestern Arizona. Based upon this work, the genus Archeolarca Hoff and Clawson is newly synonymized with Larca Chamberlin, and the following species are transferred from Archeolarca to Larca, forming the new combinations L. aalbui (Muchmore 1984), L. cavicola (Muchmore 1981), L. guadalupensis (Muchmore 1981) and L. welbourni (Muchmore 1981). Despite intensive sampling on the monument, the two new species were detected in only one cave. This cave supports the greatest diversity of troglomorphic arthropod species on the monument—all of which are short-range endemics occurring in only one cave. Maintaining the management recommendations provided by Peck and Wynne (2013) for this cave should aid in the long-term persistence of these new pseudoscorpion species, as well as the other troglomorphic arthropods.

Chaneke fogoso gen. nov. et sp. nov., are described based on specimens collected near the coast in southeastern Guerrero, Mexico. The genus is characterized by the peculiar rhomboidal shape of the subaculear tubercle, and the lack of at least one trichobothrium on the femur, patella and chela of the pedipalp, which make it the second known buthid genus with decreasing neobothriotaxy on those three pedipalpal segments, together with Alayotityus Armas 1973. Tityopsis aliciae Armas & Martin-Frias 1998, from Oaxaca, Mexico, is transferred to the new genus, resulting in Chaneke aliciae (Armas & Martin-Frias 1998), comb. nov. A cladistic analysis including all other New World “microbuthids” with decreasing neobothriotaxy, with 30 morphological characters, indicates that Chaneke is monophyletic, clearly distinct from Alayotityus Armas 1973 (from eastern Cuba) and Tityopsis Armas 1974 (from western Cuba).

The type material of Sarax buxtoni (Gravely 1915) cannot be located and has to be considered as lost. Therefore, a description compiled from a population in Singapore is provided, including morphological and taxonomical details presented for the first time. Comparisons with closely related species are supplied. Furthermore, we describe the occurrence of parthenogenesis in a population of S. buxtoni, representing the first case of asexual reproduction in a member of the genus Sarax Simon 1892.

Arctenus gen. nov. is proposed to include the type species A. taitensis sp. nov. from the Taita Hills in Kenya. This ctenid species appears to be the first representative of the Calocteninae in the African continent. Results of a parsimony analysis of morphological and behavioral characters indicated that the new species cannot be placed in any known genus and therefore validated the creation of the new genus whose autapomorphies are considered hypotheses for the genus synapomorphies. The phylogenetic relationships of the new genus are discussed and a distribution map of the unique species is presented.

Live whole specimens of two species of the harvestman Superfamily Travunioidea Absolon & Kratchovíl 1932 from the eastern United States, eight species from the western United States, six morphospecies of the family Triaenonychidae Sørensen 1886 from New Zealand, and specimens of the phylogenetically early-diverging North American triaenonychid Fumontana deprehendor Shear 1977 were extracted in methanol, and the solvent analyzed for components from their defensive secretions. The components were then mapped on a recent phylogeny of the taxa. In both eastern cladonychiid species, Erebomaster flavescens Cope 1872 and Theromaster brunneus (Banks 1902), the major component found was anabaseine, an alkaloid related to nicotine. In the western species, Paranonychus brunneus (Banks 1893), Cryptomaster leviathan Briggs 1969, Speleomaster lexi Briggs 1974, S. pecki Briggs 1974, Speleonychia sengeri Briggs 1974, Metanonychus idahoensis Briggs 1971, Briggsus flavescens (Briggs 1971) and Sclerobunus nondimorphicus Briggs 1971, the major component was N,N-dimethylphenylethylamine, implying that the travunioids from the two regions represent different phyletic lines. The secretions of the triaenonychid species, members of the genera Soerensenella Pocock 1903 and Nuncia Loman 1902, were dominated by 4-methyl-3-hexanone, and that of F. deprehendor by phenol. The completely different chemistry of the two taxa, Travunioidea and Triaenonychidae, implies significant phylogenetic differences, and the presence of phenol in F. deprehendor may suggest a long period of separate evolution for this species.

Many species roost communally but the proximate causes and ultimate functions of this widespread behavior remain poorly understood. We studied the communal roosts of two undescribed species of harvestmen in the genus Prionostemma Pocock 1903 at a Caribbean rainforest site in southeastern Nicaragua. The species are quite similar in gross morphology but differ in body coloration, male genitalia, and roosting behavior. One species roosts primarily on spiny palms while the other species, which is darker in coloration, roosts inside buttress root cavities. In a mark-recapture study, the cavity-roosting species had higher levels of individual site fidelity than found previously in the spiny palm-roosting species, perhaps because suitable cavities are scarcer than spiny palms. The tree cavity aggregations were strongly male-biased, which our review of the literature suggests is unusual for harvestman roosts. The overall sex ratio of the spiny palm aggregations was 1∶1, but some roost sites were strongly male biased while others were strongly female biased. Removing all harvestmen from 10 spiny palm roost sites shifted the overall sex ratio toward males on subsequent days, but the sites with skewed sex ratios remained skewed in the same directions despite complete turnover in roost membership. These results are discussed in relation to mechanisms of roost formation and possible sex differences in vagility, microhabitat preferences and sensitivity to disturbance. Both species also occur at La Selva Biological Station in Costa Rica but neither forms roosting aggregations in spiny palms or tree cavities there. A possible explanation for the geographic variation is that roosting patterns change over time through cultural drift.

The diverse colors of animals serve a variety of purposes, from acquiring mates to avoiding predators. Often, color patterns are not static throughout life, but change drastically during development, maturity, and senescence. While recent work has focused on the signaling value of vibrant colors in jumping spiders (Salticidae), we know very little about how colors change as spiders age; such information can provide a context for understanding the functions of and constraints on colorful traits. Focusing on Habronattus pyrrithrix Chamberlin 1924, our goals were to examine (1) the microscopic morphology of the colored body regions that males display to females during courtship (i.e., males' red faces, green legs, and white pedipalps), (2) how the colors of these regions as well as dorsal color patterns change during development prior to sexual maturity, and (3) how male condition-dependent red facial and green leg coloration changes as males age beyond sexual maturity. Although the bright white pedipalps and green legs of males appeared only upon sexual maturity, the sexes began to differentiate in facial coloration and dorsal patterning, with males developing red faces and conspicuous black and white dorsal patterning as young juveniles (ca. 2.5 mm in body length, or ca. 45% of their total mature adult body size). Even after maturity, color was not static; a male's green legs (but not red face) faded with age. Results are discussed in the context of potential functions of and constraints on color in salticids, and how they may change throughout an individual's lifetime.

Phidippus audax (Hentz 1845), a common North American jumping spider, is a visual predator that uses its highly developed eyesight to detect and forage actively for prey. We demonstrate that P. audax can survive throughout its life cycle as a scavenger. We separated 600 spiderlings into eight treatments examining all combinations of three different variables: live versus dead prey, substrate present versus substrate absent, and large versus small arenas. Over the course of the study, we recorded survival rates, instar durations, and carapace widths. Our results indicate that P. audax can survive solely on a diet of dead prey, but at significantly lower survival rates and with longer instar durations than spiders fed on live prey. Scavenging spiders, however, exhibited no significant difference in carapace widths when compared to predators. Choice tests conducted on adults indicate that spiders raised as either predators or scavengers exhibit no significant differences in prey choice when given the option of live or dead prey.

Both males and females of the spider Leucauge mariana (Taczanowski 1881) contribute material to the plugs that often occlude the genital openings of females in the field. Males were sometimes unable to remove or penetrate these plugs, but overcame others using three different mechanical mechanisms: snag the plug and pull it off; break and penetrate through it; and break its adhesion to the epigynum by injecting material under it. They used their genitalia to accomplish these tasks, despite the fact that the genital bulb lacks muscles and innervation, thus limiting the male's ability to guide genital movements precisely. The effects of two male genital structures, the conductor tip and the conductor hook on sperm transfer and genital plug removal were tested by direct observations of their morphology and behavior, and by experimental removal of structures from one but not the other palp of the same male. Removal of the conductor tip reduced sperm transfer, while removal of both the hook and the conductor reduced plug removal. A preliminary characterization of palp movements and their sequences did not reveal any behavior that seemed especially designed for removing plugs, as opposed to inseminating the female.

The burrow structure and microhabitat variables of the little known theraphosid Nesiergus insulanus Simon 1903 were determined on Frégate Island, Seychelles. The species constructed burrows in fossorial substrates, including rocks, leaf litter and bare soil as well as on the trunks of decaying trees, both recumbent and standing. The majority of burrows were predominantly found in sandy loam soil with partial protection from the sun. The density of burrows was determined to be weakly positively correlated to soil and substrate type and strongly negatively correlated to degree of exposure to the sun. The pH of the soil in which burrows are found was not significantly related to burrow sites, and variability in burrow structure was revealed. Burrow aggregations vary from single burrows to aggregations exceeding 100, distributed randomly.

Body temperature is the most important ecophysiological variable affecting all aspects of the performance of ectotherms. However, thermal preferences and tolerances of spiders have been studied only in 0.1% of spider species. Knowledge of thermal preferences and tolerances is necessary to describe the ecology of these animals, defining the preferred foraging sites or preferred shelters and reproductive sites. In this study we report for the first time the preferred temperature of Dysdera crocata C.L. Koch 1838 in the laboratory. This is an epigean spider of Mediterranean climates with large temperature fluctuations. The preferred temperature was low: 9.12° ± 5.12 °C, and actively searched. It did not vary throughout the day.

Phoneutria boliviensis (F.O.P.-Cambridge 1897) is a medically important wandering spider distributed from Central America to northern South America. This study is the first description of the natural history of this species, and presents data on several aspects of its natural history: reproductive and prey wrapping behavior, postembryonic development, and habitats in the departments of Valle del Cauca and Quindio, Colombia. Prior to copulation, the male did not engage in any courtship from a distance, but instead climbed onto the female, adopting the typical copulation position of “modern wandering spiders” (position III). Females laid up to four egg sacs; between 430–1300 hatchlings emerged after 28–34 days. After hatching, spiderlings had a third claw on all their legs and built an irregular web, where they remained until the next molt. Sexual maturity occurred after 14–17 molts, and spiders matured 300–465 days after emerging from the egg sac. The species was found in disturbed habitats associated with both dry and wet tropical forests, usually on the ground with little litter. Spiders wrapped prey in silk, moving in a stereotypically circular pattern around the prey without manipulating threads with their legs. Attachments to the substrate involved rapid movements of the anterior spinnerets, while the others remained immobile.

Orb spiders demonstrate an impressive ability to adapt their web-building behavior to a wide range of environmental and physiological factors. However, the mechanisms behind this plasticity remain poorly understood. Behavioral plasticity can be categorized as either developmental, where new neural pathways arise from learning, or activational, which rely on more costly pre-existing neural pathways. Here I argue that orb spiders and their webs in general and their response to spatial constraints in particular make an ideal model system in which to explore these two mechanisms further. I show that the spider Eustala illicita (O. Pickard-Cambridge 1889) immediately modifies its first orb web after being placed in spatially confined experimental frames without showing subsequent improvements in design of the second web. Thus, these data are in accord with the hypothesis that this spider relies on activational behavioral plasticity, which might be linked to its preferred habitat in the wild.

We report the step-by-step process of developing de novo microsatellite (SSR) loci in two Loxosceles spider species. We used reads obtained with next-generation sequencing (Roche 454) to select hundreds of potentially-amplifiable SSRs. After testing amplification and cross-amplification, we characterized 18 SSRs, 11 of which were polymorphic in Loxosceles rufescens (Dufour 1820) and seven of which were polymorphic in L. sp. Fuerteventura - Lanzarote. This method is a relatively fast and economic procedure for the development of fast-evolving nuclear markers in spiders.

The present study represents the second record of pre-ballooning behavior in Arkansas Ummidia Thorell 1875 (Ctenizidae). Mygalomorph ballooning is discussed and our observations are compared with previous authors' observations. Photographs and video of the behavior are included. Images and discussion are provided detailing genus-level identification of the spiderlings.