It is not uncommon to find courtship displays that incorporate numerous components across different sensory modalities. We studied displays in male jumping spiders of the genus Habronattus F.O. Pickard-Cambridge, 1901, which court females using a combination of ornament and motion (dance) displays coordinated with vibrational songs. To explore the diversity in Habronattus courtship complexity, we focused on quantifying the dance and vibratory displays in nine members of the Habronattus clypeatus species group, with preliminary observations on two additional species from this group. Additionally, we looked at display variation across populations in two widespread species from this group. We document three main courtship types: “stilting”, “buzzing”, and “spinning”, each identifiable by the presence or emphasis on particular display types. We found that for the widespread species H. clypeatus (Banks, 1895), different populations differed significantly and could be classified as either stilting or buzzing types. We discuss these results in relation to broader patterns of signal evolution and diversification in Habronattus.

Females use a variety of physical and behavioral features to locate potential mates and assess their quality. These male signals can be transmitted across one or multiple signaling modalities and, recently, the roles of silk-related signaling by males has received more attention. In the wolf spider, Pardosa milvina (Hentz, 1844), males use a visual courtship display to attract female attention and encourage sexual receptivity. We hypothesized that male chemotactile cues, including silk, feces, excretions and secretions, help females find prospective mates. We also suspected that females could use those cues to discriminate between males that differed in body condition. We monitored female reactions to isolated male chemotactile cues and to those same cues combined with visual signals provided by a sequestered male. Females did not change their activity in the presence of isolated male chemotactile cues. When males were included in the design, we verified that the courtship display was key to attracting the females and that males in good condition performed with more intensity. Surprisingly, the presence of male chemotactile cues repelled females; females approached males less often and tended to spend less time near courting males. This research verified that the visually conspicuous male courtship displays are condition-dependent and important in attracting a female. The chemotactile cues that were produced by isolated males caused females to move away from courting males, thus it is likely that any communication through chemical or tactile modalities is a more specific and individualized dialog that occurs during each courtship exchange.

The spider family Trechaleidae includes 17 genera and 131 species distributed throughout the Neotropical region. Most of them are semiaquatic spiders living adjacent to streams and rivers. Very few species of the family have been studied for their natural history or behavior; however four genera (Paratrechalea Carico, 2005, Trechalea Thorell, 1869, Paradossenus F. O. Pickard-Cambridge, 1903 and Trechaleoides Carico, 2005) are already known to have males that offer wrapped nuptial gifts to females. Here we describe a new species from the genus Enna O. Pickard-Cambridge, 1897, namely E. gloriae sp. nov. from Quindío, Colombia. We additionally report the presence of males of this species offering nuptial gifts to females during courtship, being the first record of this sexual trait for the genus.

The Dipluridae (Araneae: Mygalomorphae) is a recently redefined spider family of funnel-web spinners. Diplurid biology is poorly studied, especially regarding their sexual behavior, which is largely unknown for neotropical species. Diplura macrura (C.L. Koch, 1841) (Dipluridae) and Ischnothele annulata Tullgren, 1905 (Ischnothelidae) are medium-sized traditional diplurids from Brazil. We describe the courtship and mating behavior of these two species in detail, based on seven mating events under laboratory conditions observed for D. macrura and 10 for I. annulata. Both sexes of both species present courtship behaviors, and two novel spider sexual behaviors are described for I. annulata males (insertion lifting and post-brushing). Evidence for copulatory courtship is further observed for I. annulata. These sexual behaviors are analyzed and their importance is discussed in a phylogenetic context. Observed behaviors support the hypothesis of diplurid polyphyly, with Dipluridae closely related to Crassitarsae (Theraphosidae, Barychelidae, Nemesiidae, Cyrtaucheniidae and Microstigmatidae) and phylogenetically distant from Ischnothelidae. Additional biological information on both species is provided.

Sarinda marcosi Piza, 1937 is an ant-like jumping spider that shares its microhabitat with the carpenter ant Camponotus mus Roger, 1863 (Hymenoptera: Formicidae). The objectives of this study were to record S. marcosi from Uruguay, to describe the type of mimicry present in this species, and to determine the ant model it mimics and how closely it resembles it. We recorded measurements of the prosoma, opisthosoma and sternum of S. marcosi and Aphirape flexa Galiano, 1981 (Salticidae), a sympatric non-mimetic jumping spider, to calculate mimicry indices as indicators of mimicry. We created three experimental groups in which we exposed: (1) S. marcosi vs. C. mus, to test Peckhamian mimicry; (2) S. marcosi vs. A. flexa, to test the response of S. marcosi in front of a potential predator; and (3) A. flexa vs. one juvenile of Phiale roburifoliata Holmberg, 1875 (Salticidae), to test the response of A. flexa in front of a non-mimetic jumping spider (n = 15, for each experimental group). We observed similarities between S. marcosi and C. mus, both in coloration and morphology. All mimicry indices obtained were indicators of mimicry for S. marcosi. There were no attacks by S. marcosi towards C. mus and no successful attacks of A. flexa on S. marcosi, but A. flexa successfully attacked P. roburifoliata. According to these results, S. marcosi is a Batesian mimic and C. mus serves as its model. This study indicates that mimicry provides protection against predators to S. marcosi. Additionally, we provided new data about the taxonomy of the spider.

Webs of Dictyna bellans Chamberlin, 1919 in captivity included several characteristics seen in other dictynid webs, including a fine-meshed tubular retreat of non-sticky lines with multiple exits, “runways” of dense, fine non-sticky lines that were continuous with the floor of the retreat, and “ladders” of cribellum silk that zig-zagged between more or less parallel non-sticky lines. They also included two traits not previously reported for dictynids: especially tightly spaced cribellum lines with tight zig-zags that were on and very close to the substrate at the edges of the web near the retreat; and extensive coiling of cribellum silk on a few long, elevated non-sticky lines. The webs of D. bellans argue against the supposition made in some studies of web evolution that webs built especially near the substrate lack complex organization. They also indicate that the degree of coiling of cribellum lines varies among dictynids and in other cribellate spiders, and may represent a useful axis of comparison that reflects adaptations for prey retention.

Before constructing an orb web, an araneoid spider takes down and ingests the previous day's web. Nocturnal species do this either during the early evening or in the early morning and diurnal species during the early morning, times of the day when relative humidity (RH) is high. Under these conditions the hygroscopic glue droplets of a web's viscous prey capture thread attract atmospheric moisture, providing a net gain of water when a spider ingests its web. The contribution of web recycling to a spider's water budget has been estimated, but not determined empirically. This study does so for adult females of four species (Araneus marmoreus Clerck, 1757, Argiope trifasciata (Forskål, 1775), Leucauge venusta (Walckenaer, 1841), and Micrathena gracilis (Walckenaer, 1805)) by first determining the total volume of a web's glue droplets at 20% and 37% RH to estimate the water invested in web during construction. Subtracting each of these values from the web's total droplet volume at 90% RH approximates the range of water harvested when the web is recycled. High estimates of the net water gained range from 0.45% of a spider's body mass (3.01 µl water gained) in A. marmoreus to 0.88% of body mass (0.19 µl water gained) in L. venusta. In A. trifasciata, the water gained when a web is ingested is equivalent to 29% of a spider's daily evaporative water loss.

Although caterpillars commonly construct shelters on vegetation that other species subsequently occupy, few studies have focused on the spiders that often recruit to them. Fern moth larvae Herpetogramma theseusalis (Lepidoptera: Crambidae) produce large, roughly circular shelters on ferns that provide them with food and protection. Female jumping spiders Phidippus clarus Keyserling, 1885 (Salticidae) with brood or first-instar young made up over two-thirds of the spiders tallied in a study of abandoned fern moth shelters. The only other species tending young, the sac spider Clubiona bishopi Edwards, 1958 (Clubionidae), made up less than 10% of the total. Only eight species of spiders used these shelters, one-half to one-fourth that of three other studies and differing in the prevalence of jumping spiders, as opposed to a prevalence of sac spiders in the other studies. Although fern moth shelters provide important nest sites for two spiders, these sites did not enhance diversity of the spider community.

An important aspect of implementing Integrated Pest Management programs is evaluating the compatibility of insecticides with the biological attributes of the natural enemies used for pest control. In this study, we evaluated the effects of selective and non-selective insecticides on the survival and feeding behavior of Hogna cf. bivittata and Lycosa poliostoma (C. L. Koch, 1847), present in soybean crops. We used residual exposure to contaminate adult females of both spider species with the broad-spectrum insecticide thiamethoxam+lambda-cyhalothrin and the selective insecticide methoxyfenozide using concentrations of 20%, 10% and 5% of the maximum recommended field concentration. The survival rate after 120 hours post treatment and the prey acceptance rate in survivors were assessed as ecotoxicological parameters. Methoxyfenozide did not show any disruption to survival of either spider at any of the concentrations evaluated. We did not find significant differences related to mortality between the evaluated concentrations of methoxyfenozide and the control groups for both species. Nevertheless, all the concentrations of broad-spectrum insecticides we used caused mortality rates significantly higher when compared to the selective insecticide. The highest percentages with thiamethoxam+lambda-cyhalothrin were recorded for 20% and 10% concentration. Although we observed moderate mortality rates for the lowest concentrations, the exposed spiders showed a lower acceptance rate when compared to all the concentrations of methoxyfenozide and the control group; the two latter treatments were not significantly different. These results suggest that the selective insecticide can be used in different concentrations without affecting the survival or feeding behavior of either spider species.

Understanding how individual body size is affected by habitat quality allows us to assess the consequences of habitat loss and fragmentation on the morphology of arthropods. In this study, we examined the effect of habitat quality (litter depth and dry mass, understory density, canopy openness, and diameter at breast height of trees) on the body size of the litter dwelling scorpion Tityus pusillus Pocock, 1893 in fragmented rainforests of Brazil. The study was performed during the dry season in 10 forest fragments, and scorpions were collected with the aid of ultraviolet light lamps. Females, but not males, responded to the environmental attributes measured. Litter dry mass was positively related to individual body size of T. pusillus. These results suggest scorpion body size is sensitive to habitat structure. Environmental characteristics determine specific ranges of body size in scorpion populations, wherein smaller individuals inhabit sites that have less litterfall.

A new genus of pseudoscorpions of the family Chernetidae, Austinochernes, is described for two new Australian species, A. andrewaustini (type species) from South Australia and Victoria, and A. zigzag from Tasmania. They are most similar to species of the Neotropical genus PseudopilanusBeier, 1957 in the possession of a spine-like seta on the prolateral face of the chelal hand at the base of the fingers, but differ by the presence of acuminate setae on the male pedipalpal trochanter. The suspected relationship between Austinochernes and Pseudopilanus suggests that their distribution is the result of Gondwanan vicariance.

Pseudoscorpions are amongst the oldest terrestrial lineages but there is a major gap in the fossil record between the oldest fossils from the Devonian (ca. 385 million years ago) and rich fossil communities in amber that mostly originate from the Eocene of Europe. Burmese/Myanmar amber (or Burmite) from the middle Cretaceous preserves a diverse community of pseudoscorpions but these remain poorly documented, despite their exceptional preservation and potential to offer unique insights into evolutionary history. Here we describe a new genus and species of pseudoscorpion with a unique morphology of the chelicerae, Prionochthonius burmiticus gen. et sp. nov., from Burmese amber. Although some key characters remain obscure, the fossil can be confidently attributed to the basal pseudoscorpion family Chthoniidae, but it cannot be assigned to any extant or other fossil genus. Based on trichobothria patterns, it is most similar to extant genera that are found only in the Southern Hemisphere; findings that are in line with previous studies suggesting Gondwanan origins for at least some of the Burmese amber invertebrates. The fossil provides further evidence for a diverse community of litter- and soil-dwelling pseudoscorpions in the Late Cretaceous that comprises many extinct genera but represents many of the modern families. It also suggests that the diversification of chthoniid pseudoscorpions occurred well before the middle Cretaceous, and that the principle gestalt of its members has changed relatively little over time.

The suborder Cyphophthalmi (Arachnida: Opiliones) is the sister group to all remaining harvestmen. The group typically shows limited dispersal abilities, cryptic diversity and long-isolated populations. These facts make the group interesting for biogeographic, phylogenetic and cytogenetic studies. The suborder is divided into six families, all of them with a specific and long evolutionary history. However, many species are still undescribed, and their cytogenetic data are only fragmentary. This fact complicates the reconstruction of the main mechanisms of karyotype evolution in this harvestmen suborder, and utilization of the cytogenetic markers in the taxonomy of this morphologically uniform group of arachnids. Here, we present a cytogenetic study of one species of Miopsalis Thorell, 1890, of the family Stylocellidae from Mindanao (Philippines). Its karyotype consisted of mainly biarmed chromosomes (2n = 28). Interestingly, we found a multiplication of 18S rRNA gene clusters in up to seven pairs, which is one of the highest numbers in known harvestmen. These results support the likely presence of distinctive karyotype variability in an additional cyphophthalmid family, Stylocellidae (2n = 28–30).

A new species of epigean ricinuleid of the genus Pseudocellus Platnick, 1980 is described from a tropical sub-deciduous forest in Oaxaca, Mexico. The species is described based on adult males and females, protonymphs, deutonymphs and tritonymphs: Pseudocellus valerdii sp. nov. This is the second species described from the state of Oaxaca. The total number of described species of Pseudocellus from Mexico increases to 20, having the highest species diversity of known ricinuleids worldwide.

The natural and life history of the family Viridasiidae is largely unexplored. Laboratory observations on specimens of a species belonging to the genus Viridasius Simon, 1889 have shown that it constructs hanging, silken retreats for molting and hiding. These retreats are camouflaged with soil, sand, or debris, similar to the already known egg sac of this species. The retreats are similar to the silken resting cells known in dionychan spider families, such as Gnaphosidae, Clubionidae, Cheiracanthiidae or Salticidae and corroborate the recent classification of Viridasiidae as Dionycha.

In general, malformations in spiders involve chelicerae, pedipalps, walking legs, and eyes, but those affecting female reproductive structures are not so frequent. A teratological case of a spider with a duplicated reproductive structure is described. The female specimen has the typical epigyne and a second one near the spinnerets. The second epigyne is less developed and seems to be non-functional. Similar malformations have been reported for Amaurobiidae and Salticidae, and here is presented for Gnaphosidae. Although it is widely known that temperature and humidity may induce abnormalities under experimental conditions, the causes behind teratological genitalia in wild females are unknown. This case opens the question of the origin of such a malformation and the ontogeny of female reproductive organs in spiders.

Phylogenetic relationships and evolutionary patterns within the arachnid order Solifugae are poorly understood and largely unresolved due to conserved morphology and scarce genomic resources. In this study, we evaluated the role of restriction endonuclease (RE) selection in double-digest restriction-site-associated DNA sequencing (ddRADseq) as a methodology for exploring the evolutionary history of solifuges and their responses to changing desert landscapes and climate. We optimized this method by using computer simulations to explore the effect of different enzyme combinations on the process in silico. Genome data are not yet available for Solifugae, so we performed the simulations using available spider, scorpion, tick, mite and xiphosuran genomes. Guided by the simulations, we then pioneered ddRADseq in Solifugae by generating data for four samples representing two families and three genera. Our results highlight the utility of simulated data and give us confidence that ddRADseq will be ideal for studying the evolution of solifuges.