We studied how forest stand characteristics influence spider assemblage richness and composition in a forested region of Hungary. Deciduous-coniferous mixed forests dominate in the Őrség National Park. Thirty-five plots were established and sampled for spiders for three years in 70–110 year-old stands with a continuum of tree species composition. Detailed background information was acquired for stand structure, tree species composition, forest-floor-related variables and spatial position of the plots. The effect of variables was analyzed by nonparametric multiplicative regression on rarefied spider species richness and by redundancy analysis on species composition. The relative importance of variable groups was assessed by variation partitioning. Spider species richness was positively and strongly affected by tree species richness, and the species composition of the spider assemblage was influenced by the proportion of the most important tree species. This study established the importance of tree species composition, but variance partitioning analysis also showed that tree species identity and forest floor variables together explain much of the variation. These findings may guide management and conservation efforts to maintain regional diversity of the spider fauna.

Based on percentages of undescribed species collected during intensive recent sampling campaigns in South America, tropical Africa, and the Caribbean, the current global total number of pholcid species is estimated to range from about 4,000 to 5,000. With the current rate of descriptions of about 570 pholcid species per decade, this suggests that a global inventory of the family could be completed within a few decades. However, I argue that a complete (or near-complete) inventory is neither realistic nor necessary and that knowing the majority of species of a particular group will answer most questions on that taxon's biology, while being a manageable task. At current rates of description, the majority of pholcid species might be known within 10–20 years.

Vision is a remarkable sensory adaptation; however, natural selection may not favor maintenance of eye function in habitats where eyesight does not contribute to fitness. Vision loss is relatively common in cave-dwelling spiders in the temperate zone, but appears rarer in tropical caves. To date, blind spiders in the (sub)tropical Caribbean have only been described from Cuba and Jamaica, including four pholcids, a barychelid, a ctenid, and a prodidomid with reduced eyes. In our survey of over 40 caves in the Greater Antilles, mainly Puerto Rico, Isla Mona, Cuba, and Dominican Republic, we have not previously found any eyeless spiders. Here we summarize information on blind Caribbean spiders, and describe two newly discovered species representing two families, from a single cave, Cueva Seibo, in the Dominican Republic. These are the eyeless Ciba seibo n. gen., n. sp. (Ctenidae) and the vestigial-eyed Trichopelma maddeni n. sp. (Barychelidae). Cueva Seibo appears to be an energy-poor system with a relatively small bat population and is physiologically unique amongst caves we surveyed. We postulate that troglobiomorphism in the Caribbean may result from individual cave environments and hypothesize convergent eye loss within this cave, as most members of both families, including epigean species from the Dominican Republic, have normal eyes. However, another blind species, Ciba calzada (Alayón 1985) n. comb., occurs in a cave in Cuba and it remains to be tested if eye loss occurred in these two convergently, or if their shared lack of eyes is homologous.

A new species of the genus Charinus Simon 1892 from the state of Minas Gerais, Brazil, is described. Charinus jibaossu sp. n. is morphologically close to C. mysticus Giupponi & Kury 2002 and shows both a marked secondary sexual dimorphism in the pedipalps and an interesting polymorphism in the spines of the distitarsus. The new species is endangered because it inhabits a region highly impacted by mining activities.

Mountain habitats host a large number of endemic species, which are vulnerable to climate change. We studied scorpion communities of the Central Andes in Argentina at 17 sites located in Andean and extra-Andean areas between 900 and 3400 m elevation. Using pitfall traps, we collected 254 individuals from seven species, all from the Bothriuridae family. Although we expected a decrease in richness towards the high altitude sites, we did not find a clear pattern. In turn, the lowest site was the most diverse and rich; other sites had similar richness values regardless of altitude. High-altitude sites were characterized by the presence of Orobothriurus Maury 1975 species. Orobothriurus alticola (Pocock 1899) has been found exclusively on Andean sites located above 3200 m, and O. grismadoi Ojanguren-Affilastro et al. 2009 has only been found at extra-Andean sites on Cerro Nevado. Community composition showed an association with altitude, with some species exclusive to high altitude sites and others only found at lower sites. Because of the ecological importance of scorpions in arid environments, this study provides base information that may help design conservation actions for these habitats. In particular, the presence of high-altitude specialists like Orobothriurus species seems relevant, since they may be used as bioindicator species.

Social experience is well-known to influence female mate preference in vertebrate animals, but such effects have been studied less in invertebrates. Studies have documented flexibility in female mate choice in the wolf spider genus Schizocosa as a result of juvenile female experience with courting adult males. Here we investigate whether juvenile exposure to male courtship influences adult female species-level mate recognition in the wolf spider Schizocosa ocreata (Hentz 1844) and its sympatric sibling species S. rovneri (Uetz & Dondale 1979). Because these species overlap in range, contact between them is probable as interspecies hybrids are occasionally found in nature. Juvenile females were exposed multiple times to conspecific or heterospecific male courtship. Upon maturing, each exposed female was paired with an adult male of the same or different species to which it had been previously exposed, and was observed to determine receptivity and willingness to copulate. Results suggest that juvenile experience plays only a minor role (if any) in development of female mate recognition at the level of species, because the type of juvenile experience (conspecific vs. heterospecific) did not significantly affect mating outcome for either species. However, some context-specific effects of experience were observed, because the amount of juvenile exposure to adult male courtship affected adult receptivity of females in both species in different ways. In S. ocreata, the overall amount of juvenile experience (rather than type) influenced adult female receptivity and aggression toward heterospecific males; females with more exposures were initially more receptive and less aggressive to heterospecifics. In S. rovneri, neither type nor amount of juvenile exposure had significant effects on female receptivity towards conspecific males, although females exposed to heterospecific male courtship as juveniles were initially less receptive towards conspecific males than were unexposed females. While these results confirm earlier findings of behavioral reproductive isolation at the species level, they differ from some other studies, raising intriguing questions about varying degrees of behavioral and genetic isolation in different geographical populations of these two species.

Animals are commonly categorized as diurnal, nocturnal, or crepuscular depending on the times of day when they are most active. These categories, although convenient, would be more useful if we knew more about how closely animal activity conformed to the labels. Similarly, if we knew more about the degree of nocturnality or diurnality of a particular species, we would have increased understanding of the selective forces acting on it. To clarify the intensity of nocturnality or diurnality in lycosoid spiders, we measured activity in 46 spiders divided among three congeneric species of fishing spiders (Pisauridae) and five species of wolf spiders (Lycosidae), in an austere laboratory setting. Overall, the three pisaurid species, pooled, were less than half as active as the five lycosid species, also pooled. All three species of fishing spiders and four of the five species of wolf spiders were strongly nocturnal in their activity. Only one species, the wolf spider Piratula minuta (Emerton 1885), was diurnal. None of the individual spiders that showed statistically significant nocturnal or diurnal activity (31 of 31 lycosids, 14 of 15 pisaurids) was purely nocturnal or diurnal. In all individual cases except for a single ambivalent Dolomedes tenebrosus Hentz 1844 (Pisauridae), statistically strong nocturnality was accompanied by substantial activity during the light hours, and statistically strong diurnality was accompanied by substantial activity during the dark hours. We discuss the overall low variability in activity patterns among the fishing spiders in comparison to the much higher variability among the activity patterns of the wolf spiders, the common but not ubiquitous presence of ultradian periodicities in individual spiders, and the significance of the fact that none of the individual spiders was strictly nocturnal or strictly diurnal.

Terrestrial animals often inhabit stochastic boundaries between terrestrial and aquatic habitats which are under constant risk of flooding. In these circumstances, terrestrial arthropods often exhibit behavioral and physiological adaptations to cope with this risk by either avoiding flooding or tolerating submersion. We present the results of a study designed to explore submersion tolerance in a lakeshore population of Pardosa lapidicina (Emerton 1885), a eurytopic lycosid. Spiders were submerged in lake water for 4, 8, 11, or 16 hours, then removed and tested for responsiveness. Each spider was checked for responsiveness a second time after an eight-hour period in a dry vial. Spiders that were submerged for longer periods were less likely to be responsive immediately after removal. However, between 7% and 38% additional spiders resumed activity eight hours after removal, their recovery depending on their time submerged. This suggests that adult P. lapidicina can survive long periods of submersion in a quiescent state and later resume activity.

We conducted systematic sampling to examine the microhabitat distribution of the Nearctic linyphiid Drapetisca alteranda Chamberlin 1909; adults are found almost exclusively on tree trunk surfaces. Sampling was conducted in a 1 ha plot in which all trees over 10 cm dbh had previously been identified, mapped, and measured. Tree trunks were sampled for D. alteranda by brushing spiders into beating sheets. We sampled equal trunk surface areas (0.5–2.0 m) of the four most abundant tree species on the plot: Quercus alba, Fraxinus pennsylvanica, Tilia americana, and Carya ovata. We measured tree bark furrowing depth at 15 locations around each tree. We analyzed the data with a General Linear Mixed Model, assuming Poisson distribution. Tree species and furrowing depth, but not tree size, were significant predictors of total number of D. alteranda collected. Eighty-four percent of the spiders were collected on T. americana, and the relationship between spider abundance and furrowing depth was negative. As a separate test for D. alteranda vertical distribution, we divided the lower 3 m of selected tree trunks into six 0.5 m sections, sampling each separately. Regardless of tree species, height above ground was a significant predictor of female (but not male) D. alteranda occurrence, with 52% of the females found 0.5–1.0 m above the forest floor. These results suggest that the microhabitat distribution of D. alteranda is broadly similar to that of the Eurasian species D. socialis, a species that matures in leaf litter and migrates mostly to the lower regions of tree boles to forage as adults.

The feeding ecology of most Oecobius species is poorly understood; nevertheless, the limited literature available suggests that obligate myrmecophagy is common in this genus. Recent evidence suggests that some species might do not share this trait, but could be locally specialized predators. We describe the diet and prey selectivity of the spider Oecobius concinnus (Simon 1893), a common pantropical species. Samplings of actual and potential prey for this species were made in the city of Ibagué, Colombia. Ants were the dominant prey. Other prey included in its diet were dipterans. These results suggest that O. concinnus is not an obligate myrmecophagous spider. Nevertheless, further studies will evaluate other aspects of the biology of this species to reveal its trophic strategy.