Spiders use chemicals to interact with conspecifics, heterospecifics and with their environment. The focus of most past reviews on chemical communication in spiders has been on female sex pheromones (chemicals produced by females to attract or elicit courtship in males) and their biological function or chemical structure. Here, I present a methodological overview to provide suggestions for how to approach future studies on pheromone identification in spiders. This research needs more encouragement, as female sex pheromones have been described for only 11 spider species so far. Male pheromones and behavioral evidence are also presented in this work as such data have been largely overlooked in past studies, with only one male sex pheromone having been identified. Subadult females of many different families experience male cohabitation. Here it is discussed whether a subadult female pheromone or a subadult female chemical cue (unintended information understood by the receiver) may mediate this behavior. In the next section of this work, I discuss female reaction to chemical signals of conspecific females, as this interaction deserves further discourse. Chemical interactions with other species and the environment are discussed in the last section, where recent reports have extended the knowledge and pointed out types of interactions that have been overlooked in past reviews.

Pseudoscorpions are among the most diverse of the smaller arachnid orders, but there is relatively little information about the distribution of these tiny animals, especially in Neotropical caves. Here, we map the distribution of the pseudoscorpions in Brazilian caves and record 12 families and 22 genera based on collections analyzed over several years, totaling 239 caves from 13 states in Brazil. Among them, two families (Atemnidae and Geogarypidae) with three genera (Brazilatemnus Muchmore, 1975, ParatemnoidesHarvey, 1991 and Geogarypus Chamberlin, 1930) are recorded for the first time in cave habitats as, well as seven other genera previously unknown for Brazilian caves (Olpiolum Beier, 1931, Pachyolpium Beier 1931, TyrannochthoniusChamberlin, 1929, Lagynochthonius Beier, 1951, Neocheiridium Beier 1932, Ideoblothrus Balzan, 1892 and Heterolophus Tömösváry, 1884). These genera are from families already recorded in this habitat, which have their distributional ranges expanded for all other previously recorded genera. Additionally, we summarize records of Pseudoscorpiones based on previously published literature and our data for 314 caves. We present these data in maps, considering the Brazilian biogeographical provinces. For the genus SpelaeochernesMahnert, 2001, we reevaluate its Schiner-Racovitza status and propose that all species represent troglobites. Finally, we discuss the ranges of the pseudoscorpion families/genera.

The pseudoscorpion genus IndogarypusBeier, 1957 is reviewed and its characters are discussed. Based on the review of these characteristics Indogarypus is synonymized with Geogarypus Chamberlin, 1930. New descriptions of Geogarypus indicus (Beier, 1930), G. ceylonicusBeier, 1973 and G. nepalensis Beier, 1974 are provided.

Stridulatory organs have not been previously investigated for harvestmen in the family Cosmetidae. During a field study, we observed the infrequent production of vibrations by adult Cynorta marginalis Banks, 1909. Using SEM, we examined the surfaces of several appendages for potential stridulatory organs. Our observations indicate that C. marginalis has denticles on the mesal surfaces of the basichelicerites that when rubbed together may function as an isomorphous stridulatory organ. In addition, there are denticles on the ectal surfaces of the basichelicerites and furrowed ridges on the femora of the pedipalps that may represent heteromorphous stridulatory organs. We did not observe any sexual dimorphism in morphology at either anatomical location. We also examined the appendages of two additional cosmetid harvestmen: Paecilaema inglei Goodnight & Goodnight, 1947, a species that also stridulates when held and Erginulus clavotibialis (Pickard-Cambridge, 1905), a species that has not been observed to produce vibrations. As in C. marginalis, we observed denticles on mesal and ectal surfaces of the basichelicerites and a furrowed ridge on the mesal surfaces of the femora of the pedipalps of adult P. inglei. In contrast, the basichelicerites of E. clavotibialis had relatively fewer and smaller denticles on the external surfaces of the chelicerae and the mesal surface of the femora of the pedipalps lacked ridges and were relatively smooth. Our comparative morphological data supports the hypothesis that there are cosmetid harvestmen that may use surface features on the chelicerae and pedipalps to produce vibrations which may function as a secondary defense mechanism.

Recent collecting in the Dalmatian karst uncovered a fascinating new species of cave-obligate harvestman, here described as Lola konavoka sp. nov. The new species closely resembles Lola insularisKratochvíl, 1937, the type species of the genus, in male secondary sexual structures (presence of cheliceral boss and labial prongs) and genitalia (glans sigmoid and with basal lobes), supporting these characters as diagnostic for the genus. Males of L. konavoka have smaller dimorphic structures and genitalia with unbranched stylus and basal lobes, unlike in L. insularis. Somatically, L. konavoka is more strongly troglomorphic, having a smaller eyemound, longer legs, and higher tarsal count which exceeds that of all European Phalangodidae, including the most troglomorphic member, Paralola buresiKratochvíl, 1951. All species were compared and ranked in degree of troglomorphy. The least modified, troglophiles, include two primarily surface-dwelling species (Scotolemon doriae Pavesi, 1878, and S. terricola Simon, 1872) and one cave-obligate species showing little modification (S. lucasi Simon, 1872). The remaining species, troglobites, have some degree of eye loss [Ptychosoma espagnoli (Rambla, 1973), Ptychosoma balearicum (Rambla, 1977), both Lola spp., and Paralola buresi]. The distribution of the cavernicolous species is plotted. The troglophiles occupy the central region (Pyrenees through greater Italy). The troglobitic species are in a linear arrangement, with the least troglomorphic (Ptychosoma espagnoli) in the west and most troglomorphic (Paralola buresi) in the east. Clinal variation in troglomorphy has previously been recorded in the Nearctic phalangodid genera Texella Goodnight & Goodnight, 1942, and Banksula Roewer, 1949, where the most troglomorphic members are also to the east as well as north.

Fishing spiders, Dolomedes Latreille, 1804 (Pisauridae), are thought to be important predators in semi-aquatic ecosystems, but relatively few studies have investigated feeding ecology of Asian species. Here, we report on the diet of the Okinawan fishing spider, Dolomedes orion Tanikawa, 2003, the largest cursorial spider in Japan, based upon field observations on Amami Oshima Island in Kagoshima Prefecture and a literature review. A total of 13 predation events were observed in field surveys and 10 records were found in the literature. Together, these indicate the consumption of a broad range of food items from arthropods to vertebrates, e.g., insects, harvestman, conspecific spiders, crustaceans (freshwater crab and prawn), two species of endemic frogs (Rana ulma, Odorrana narina), and an Okinawa tree lizard (Japalura polygonata polygonata). Because this species has substantial energy demands for growth, large prey items such as crustaceans and vertebrates seem to be its primary food resources with 10 of 23 prey items [= 43%] belonging to these two large-sized prey groups.

Scorpion stings are prevalent and sometimes deadly. Rosemary oil deters phytophagous insects, so we investigated whether scorpions, which prey on insects, might also be deterred. We tested the repellant properties of rosemary oil on adult Centruroides vittatus Say, 1821 scorpions in an arena lined with sand infused with rosemary oil on one side and mineral oil on the other. A middle, neutral zone consisting of dry sand ensured independence between the two sections. Scorpions spent significantly more time on the mineral oil sand (P = 0.0031). Next, we tested 1,8-cineole, the primary component of rosemary oil, against mineral oil and found no preference (P = 0.789). These findings suggest that scorpions may be repelled holistically by rosemary oil, rather than the tested primary component. Future studies could test other components of rosemary oil in varying combinations to determine the critical ingredients responsible for the avoidance behavior induced by the complete mixture.

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General insights in sexual selection can be enhanced by the addition of data from under-studied species. Understanding the natural history of these species is acritical first step. Here, we report detailed field observations of Tetragnatha straminea Emerton, 1884, a long-jawed orb weaver common in riparian meadows. Relatively little is known about this spider, in which the elongate chelicerae of males lock with those of females during copulation. We assessed courtship, mate-guarding, intrasexual competition and predictors of female receptivity to mating. As inter-sexual fang-lock is critical to successful mating, we also examined male and female cheliceral allometry. Finally, we observed patterns of aggregative clustering during peak-mating periods, as this may indicate elevated levels of intra-sexual aggression. Overall, females were polyandrous, and it was not possible to predict female receptivity based on the number of males present or female aggressive behavior towards males. Courtship was not evident prior to mating attempts, although some males remained in close proximity to females for extended periods. Towards the middle-to-end of the mating season, multiple females would aggregate in clusters, where elevated intra-sexual aggression and frequent copulations occurred. Our observations suggested that fang-lock clasping may be important in intra-sexual agonistic interactions as well as mating, particularly during mid-season web aggregations. Consistent with this, morphological data suggest a trend towards larger chelicerae in males rather than females. Tetragnatha straminea may be ideal for testing hypotheses regarding effects of seasonal variation in sexual selection, and the evolution of structures that serve more than one sexually-selected function.

The ecological niches of the three Iberian Argiope species have not been studied in quantitative detail, and recently developed approaches for assessing niche overlap have rarely been applied to invertebrates. This study aimed to quantify the climatic niche differences between Argiope bruennichi (Scopoli, 1772), A. lobata (Pallas, 1772) and A. trifasciata (Forsskål, 1775) in the Iberian Peninsula. An extensive occurrence database for the three species was compiled from the literature, a citizen science project (Biodiversidad Virtual) and a social network (Flickr). Niche comparison and recursive partitioning analyses were used to compare and characterize the niches of these species using regional climatic information. The three Argiope species had different distribution patterns within the Iberian Peninsula with a clear degree of sympatry. Despite an appreciable niche overlap, the three species had significantly different climatic niches. A. bruennichi was present in colder and more humid environments, while A. lobata and A. trifasciata selected warmer, drier environments. A. trifasciata preferred areas with higher minimum temperatures than A. lobata and avoided continental environments that the two other species tolerated. Despite these differences, the Iberian Peninsula contained a broad range of suitable environments where more than one species co-occurred. Further studies are needed to explore these species relationships, particularly given the trend of ranges shifting north due to global warming. Considering both the results of this study and the increasingly xeric conditions in the Iberian Peninsula, A. lobata and A. trifasciata may benefit at the expense of a retraction of A. bruennichi.

In this study, field and laboratory observations of the feeding ecology (natural diet, prey acceptance, prey capture behavior and capture efficacy) of the theridiid Euryopis episinoides Walckenaer, 1847 were combined to reveal its trophic niche and capture efficacy and to test the hypothesis that this species is an ant-eating specialist. Natural prey was investigated from individuals collected in southern Portugal and was found to contain only ants of several species. Prey acceptance experiments revealed that spiders accepted several prey types occasionally, but ants, termites, and fruit flies were accepted with a high frequency. Prey capture behavior was similar for four tested prey types (Formicinae and Myrmicinae ants, termites, and fruit flies). Hunting usually started with a wrapping sequence when the spider threw the silk from its spinnerets onto the prey while circling around it. Then the spider bit the prey and wrapped it in more silk. Afterwards the spider waited for some time until the venom paralyzed the prey. Finally, the spider attached the immobilized prey to its spinnerets and carried it away before feeding. Wrapping time, number of bites, and waiting time differed among the four prey types, with the longest wrapping time, the highest number of bites, and the longest waiting time recorded during the capture of Myrmicinae ants. We conclude that E. episinoides is an ant-eating specialist possessing an effective capture strategy for the capture of ants. Yet, E. episinoides spiders maintain the ability to capture alternative prey.

Several studies have shown that sperm viability (SV) is a key trait during sexual competition. However, this has not yet been tested in spiders as no protocol has been developed to quantify SV. Here, we describe a methodology for estimating SV using the pholcid spider Holocnemus pluchei (Scopoli, 1763). In this method, male spermatozoa were released from the sperm ducts of copulatory bulbs in 50 µl saline solution and mixed with a vortexer. Finally, 10 µl of the sperm solution were combined with 1 µl of GelRed stain. We counted a total of 200 cells and calculated the percentage that was not stained. Males showed almost 100% of live sperm inside their genital bulbs. GelRed stain demonstrated a high effectiveness to distinguish between dead and living sperm cells in spiders and it is thus a more reliable option compared to the dyes typically used, such as propidium iodide and sybr14. The high SV in H. pluchei may be explained by the multiple mating nature of females, which suggests a selection for enhanced effectiveness during sperm competition within the female genital tract.

Araneid orb weavers systematically weaken the radii in their orbs by partially or completely removing the provisional radial lines laid during radius construction. Removal of provisional radii by Micrathena duodecimspinosa (O. Pickard-Cambridge, 1890) tended to be less complete for those radii that were attached later during the radius construction stage to the same frame line; this pattern differed from previous observations of provisional radius removal in two other araneids. Patterns of removal in M. duodecimspinosa were not in accord with a previous hypothesis that provisional radius removal functions to adjust radial tensions. In addition, M. duodecimspinosa moved in complex, jerky paths during radius construction that did not occur in previous or subsequent stages of construction. These movements resulted from the spider vibrating the entire web as she moved; their functional significance is unclear.

The ‘white-headed’ spiny trapdoor spiders of the Euoplos mcmillani-group are revised, and three new species are described from the biodiversity hotspot of south-western Western Australia: E. cornishi sp. nov., E. kalbarri sp. nov. and E. saplan sp. nov. Two previously described species, E. ballidu (Main, 2000) and E. mcmillani (Main, 2000), are further re-described and re-diagnosed. The mcmillani-group of Euoplos are remarkable for the unique ‘bright white’ carapace coloration of males, and we here document the known diversity and conservation status of these rare and enigmatic spiders.

Attus mandibularisTaczanowski, 1871, Attus cabanisiTaczanowski, 1872 and Asaracus roeweriCaporiacco, 1947 are here transferred to RishaschiaMakhan, 2006. After the study of type specimens and additional material, these taxa, along with the type species Rishaschia amrishiMakhan, 2006, are all considered variations within a single species. Herein, the male is redescribed and the correct female is formally described for the first time. The coiling of the embolus around the tegulum varies continuously from 450° to 540°, even at the same locality. Distribution records are given, showing the presence of the species in the Amazon forest from the coast of the Atlantic Ocean to the foothills of the Andes.

A new species of the pseudoscorpion genus Metawithius Chamberlin, 1931 is described from Kerala, India. Detailed morphological descriptions, diagnostic features and illustrations of Metawithius keralensis Johnson, Mathew, Sebastian & Joseph, sp. nov. are provided. Detailed redescription and illustrations of M. nepalensis (Beier, 1974) are also provided. The current distribution of all the known Metawithius species is mapped. Metawithius parvus (Beier, 1930) from Travancore, India is recognised as a species of Chernetidae.

A faunistic inventory from an oak forest near Pico de Orizaba National Park revealed the presence of two new species of pseudoscorpions. Atherochernes breviductus sp. nov. of the family Chernetidae is represented by 286 mature specimens, and is the first record of this genus for the country; Serianus orizabensis sp. nov. of the family Garypinidae is represented by 44 adults and is the first record of the family for the State of Veracruz. Most individuals were collected by sifting leaf litter and processing with Berlese funnels. The new taxa are hereby described and documented with illustrations and high-quality microphotography. The relationships of AtherochernesBeier, 1954 with other chernetids was investigated with a molecular phylogeny. In addition, the species Mexichelifer reddelliMuchmore, 1973 and Mundochthonius mexicanusMuchmore, 1973 are recorded for the first time in the state of Veracruz.