Journal of Arachnology

Published by American Arachnological Society
Online ISSN: 1937-2396
Publications
Article
The 745 palpigrads (micro-whip scorpions) collected in a 12 month period in the soil (0-7 cm depth) of a secondary upland forest (120.1 ± 50.8 ind./m²/month) and of a primary upland forest (29.4 ± 20.2 ind./m²/month) near Manaus all belong to the species Eukoenenia janetscheki Conde 1993. About 75% of all specimens inhabited the mineral subsoil (3.5-7 cm depth) where monthly catches were negatively correlated with temperature and moisture content of the soil Females were almost twice as abundant as males. The lack of a distinct reproductive period and the presence of juveniles and adults (both sexes) throughout the year indicate a plurivoltine mode of life. No specimens were caught on or above the soil surface. Abundances of E. janetscheki are compared with those of the Schizomida (tartarids) and Thelyphonida (vinegaroons) from the same study sites. E. janetscheki also represented the palpigrads obtained from the soil of three other upland forest types in Central Amazonia (0-14 cm depth) and accounted for 0.1-0.3% of the total arthropod fauna.
 
Article
We investigated host specificity, the effects of host size, and the effects of the size, structure and occupancy of host webs on the abundance of the kleptobiotic spider Argyrodes antipodianus O.P.-Cambridge 1880. The kleptobiont is not host specific, but does prefer orb webs that are surrounded by a scaffold of threads (barrier-web). Across all hosts, host size had little effect on the abundance of the kleptobiont, while host density and the presence of other species of Argyrodes on webs had no effect. Web diameter, although not strongly related to the abundance of A. antipodianus in the field, limited kleptobiont numbers in greenhouse experiments. On webs of the Golden Orb Spider, Nephila plumipes (Latreille 1804), numbers of A. antipodianus were not affected by size of the scaffold or by aggregation of host webs. However, presence of host males was associated with a significantly higher abundance of A. antipodianus, suggesting that these kleptoparasites may take advantage of distracted females and impose a cost on mating in N. plumipes.
 
-Pairwise distances (uncorrected P) between ND1 sequences of Latrodectus spiders. 
Article
New Zealand's endemic sand dune Latrodectus widow spider species, L. katipo and L. atritus, possess behavioral and physiological attributes likely to promote dispersal over large distances. Morphological, physiological and behavioural similarities between L. katipo and L. hasselti, an Australian endemic, suggest gene flow may occur across the Tasman Sea. In this study we examine intraspecific and interspecific genetic relationships within the ND1 gene region between L. katipo, L. atritus, L. hasselti and L. hesperus to assess whether the genetic evidence supports current taxonomic species designations. We found low interspecific pairwise distances among L. katipo and L. atritus populations, suggesting either introgression, incomplete lineage sorting, or that the current taxonomic distinction between the two species may be invalid. Parsimony and maximum likelihood analyses were inconclusive as to the relationships between the New Zealand Latrodectus species and the Australian L. hasselti. Low pairwise distances between L. hasselti and the New Zealand widow fauna indicated that L. katipo and L. atritus were not present in New Zealand before the fragmentation of Gondwana.
 
Article
Spiders have been advocated as valuable bio-indicators of forest ecosystem 'health.' However, the numbers and types of spiders that are recorded at a site will usually be highly dependent on the sampling method employed. The use of lethal, indiscriminate invertebrate sampling techniques is undesirable when investigating rare species, or sampling within areas of high conservation status. Therefore we used non-lethal artificial tree-mounted shelters to monitor arboreal spiders in nature reserves near Christchurch, New Zealand. After three months, over 60% of the shelters had been used by spiders, increasing to 91% after twelve months. There were significant differences in the numbers of spiders found in the shelters at the different sites. However, factors such as the species of tree the shelter was attached to, ground vegetation, and levels of incident light did not affect the likelihood of a shelter being occupied. The species composition of the spider faunas in those sites regarded as high quality forest remnants was dissimilar to the faunas found in the low quality reserves. However, although spiders were more abundant in the high quality sites compared with the poorest stands of woodland, they were not more species rich. The shelters are inexpensive and easy to manufacture and are useful for long-term non-lethal monitoring of spider communities. They also have good potential as a tool for studying spider phenology, population dynamics, behavior, and as a collection/carriage device for live specimens used in conservation translocations.
 
Article
Thesis (Ph. D.)--Stanford University, 1971. Includes bibliographical references (leaves 111-126). Typescript photocopy.
 
-Auto-Montage images of pseudoscorpions recovered from Pachacamac samples. Left to Right: dorsal view of specimen, ventral view of specimen. Scale bar ¼ 500 lm. 
-Confocal laser scanning microscopy image of the dorsal view of a pseudoscorpion recovered from Pachacamac sample P17. Scale bar ¼ 500 lm. Figure 3.-Confocal laser scanning microscopy image of the ventral view of a pseudoscorpion recovered from Pachacamac sample P17. Scale bar ¼ 500 lm. 
-Confocal laser scanning microscopy image of a disarticulated pseudoscorpion pedipalp recovered from Pachacamac sample P17. Scale bar ¼ 500 lm. 
-Collection data and subsample weights for Pachacamac burial sediments containing pseudoscorpion fragments. Weight is expressed in grams (g).
Article
Fragmented remains of pseudoscorpions belonging to the family Cheiridiidae (Arachnida, Pseudoscorpiones) were recovered from Ychsma polity (c. AD 1000-1475) burial sediments from Pachacamac, Perú. Sediments from 21 burials were examined following rehydration in 0.5% trisodium phosphate for 48 h and subsequent screening through a 250 μm mesh. Materials larger than 250 μm were surveyed for the presence of arthropods. A total of two samples contained pseudoscorpion fragments, which were collected and quantified to determine the minimal number of pseudoscorpions present per gram of each sample. Following quantification, pseudoscorpion specimens were imaged utilizing confocal laser scanning microscopy (CLSM) to assist with identification efforts. Specimens have morphological characteristics consistent with those found in members of the pseudoscorpion family Cheiridiidae. Members of this family have not been previously described from archaeological materials recovered from Perú, and the implications of pseudoscorpions as members of the archaeological corpocenosis have not been fully interpreted. Herein, we report the first recovery of pseudoscorpions from archaeological materials at Pachacamac, and discuss the significance of their roles in the archaeological corpocenosis.
 
Article
We investigated the pattern of molecular variation with respect to secondary structure in the 16S ribosomal RNA gene and its phylogenetic implications for arachnids with a focus on spiders. Based on a model by Gutell et al. (1996), secondary structures were proposed for the 3′ half of 16S in the mygalomorph spider Aptostichus atomarius. Models were also constructed for a hypervariable length of the 16S in three other arachnids, which revealed a trend of stem and loop reduction in more advanced arachnids. Using a simple statistical approach to compare functional regions, we found that internal and external loops are more variable than stems or connection regions. Down-weighting or excluding regions which code for the more variable loops improved tree topologies by restoring the monophyly of the genus Aptostichus, a group supported by combined 16S, COI, and morphological data in other analyses. This study demonstrated the utility of considering secondary structure for DNA sequence alignment and phylogenetic reconstruction in spiders.
 
Article
Spider venom is assumed to be used primarily to subdue larger prey and secondarily in defense. Rabidosa rabida (Walckenaer, 1837) is a non-web building, venomous spider. Its feeding behaviors suggest venom may not be as important as previously expected in prey capture and immobilization. We conducted feeding tests to examine the importance of venom injection in prey capture for R. rabida. Groups of large crickets were offered to two groups of adult female spiders with either functional or glue blocked venom pores but otherwise functional chelicerae. Our results could not confirm a significant effect of venom availability on prey capture and showed that spiders could immobilize prey without the use of their venom. These results expand upon previous studies suggesting prey capture was possible without the use of the fangs, but prey immobilization required venom. This study suggests our understanding of spider prey capture and venom use is incomplete.
 
Article
Although sexual size dimorphism is a widely observed phenomenon in nature, the selective forces that led to it are still controversial. Here we study sexual dimorphism in the static allometry of the legs of a large ground spider, Grammostola rosea (Walckenaer, 1837). We found that this species has a moderate sexual size dimorphism and males have longer legs relative to body size than females, similar to other ground spiders. We propose that male mate searching behavior may be a relevant factor in the genesis of this phenomenon. The longer extremities in males with respect to mass than in females would lead to an optimization of the costs associated with locomotion, because males have smaller masses and longer legs than the females both in absolute terms and relative to body mass.
 
Article
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.
 
-Mean total duration (s) (þSE) of jerky tap behavior (active courtship) for male Schizocosa ocreata exposed to the silk and chemical cues of females in the presence or absence of predator cues.
-Mean total duration (s) (þSE) of tapping behavior for male Schizocosa ocreata exposed to the silk and chemical cues of females in the presence or absence of predator cues.
-Mean total duration (s) (þSE) of leg raise behavior for male Schizocosa ocreata exposed to the silk and chemical cues of females in the presence or absence of predator cues. 
-ANOVA results for mean total duration (s) of behaviors for male Schizocosa ocreata. (* Indicates significance after Bonferroni correction (a¼0.007))
-Mean total duration (s) (þSE) of grooming behavior for male Schizocosa ocreata exposed to the silk and chemical cues of females in the presence or absence of predator cues. 
Article
Sexual signals play a critical role in mate attraction, but fitness benefits of signal production depend on a number of external and internal influences. Sexual signaling can be energetically expensive, and has potential to attract unwanted attention from predators. Male brushlegged wolf spiders, Schizocosa ocreata (Hentz, 1844) (Araneae: Lycosidae), actively signal to females in the leaf litter habitat during their spring breeding season, but face a tradeoff between current and future reproduction as the season progresses. The terminal investment hypothesis predicts that with fewer available females, increasing risk of predation, and stronger influence of senescence as the season progresses, males should take greater risks to secure mating. We explored this idea by exposing males of increasing ages to female cues alone or female cues combined with predator cues. We found little or no direct evidence to support the terminal investment hypothesis in this species, in that males across all ages essentially ceased active courtship in the presence of predator cues, that is, there was no age related increase in courtship investment in the presence of predator cues. However, we found distinct evidence of senescence in males based on age-related changes in behavior, which has not previously been directly explored in this species. While males maintained similar levels of active courtship across all age classes (in the absence of predator cues), older males increased their relative investment in maintenance behaviors (grooming) and decreased non-courtship display behaviors such as tapping and leg raises. These findings suggest that studies of male behavior in this species should be carefully designed to control for age-related variation in behavioral response.
 
Article
In mating systems that include semelparous reproduction and/or scramble competition, synchronous maturation of the sexes is vital for success. However, food limitation may alter the onset of maturation or the overall quality of the mature individuals and affect reproductive success. We examined the role of feeding history (well-fed vs. long-term deprivation) on female reproductive timing and its correlation with temporal patterns of receptivity behavior in the wolf spider Schizocosa ocreata (Hentz, 1844). We found that feeding history influenced developmental time and delayed maturation in long-term food-limited females. There was no significant difference in relative condition between treatments, yet well-fed females showed higher rates of receptivity. Peak receptivity behavior was correlated with the estimated overall mass of female ovaries/eggs, with females that possess larger ovaries and eggs showing more receptive behavior. This supports the hypothesis that while a food-limited female may attain maturity, the limiting factor underlying reproductive success is gonad maturation.
 
Article
The ambient temperature of an environment has potential to influence many aspects of the behavior and physiology of small-bodied ectotherms, including brush-legged Wolf spiders Schizocosa ocreata (Hentz, 1844) (Araneae: Lycosidae). Temperature varies significantly, and often unpredictably, in their habitat throughout the spring breeding season, and is known to influence male Schizocosa courtship behavior. Currently unknown is what effect fluctuations in ambient temperature alone might have on critical, non-behavioral sexual signals such as female silk and chemical cues. We collected cues from mature, virgin females and subjected each sample to one of three thermal treatments (40°C, 20°C, or -12°C), at constant humidity. We presented treated female cues to mature males and recorded male response across treatment types as a behavioral indicator of signal degradation. There were no significant differences across treatments in the frequency or duration of male behaviors, including critical courtship and exploratory behaviors. Our results suggest that thermally induced degradation of female sexual signals is negligible for this species and likely has little or no influence on male behavior.
 
Article
Sexual cannibalism is common in many species of arachnids. Studies investigating Dolomedes tenebrosus Hentz, 1844, have even discovered the occurrence of obligatory male self-sacrifice during copulation. In this system, females subsequently cannibalize males, and this cannibalism leads to higher fitness for both partners. Unfortunately, our understanding of the evolution of such an extreme mating system is challenged by the absence of information for close relatives. To that end, this study explores the courtship behavior, mating system and cannibalism dynamics of the spider Dolomedes scriptus Hentz, 1845. To determine whether female and male D. scriptus mate multiply, we recorded interactions of repeatedly exposed focal females and focal males to new mating partners for three days. We also quantified attacks and cannibalism events that occurred both before and after every copulation. We found male D. scriptus court females by waving their forelegs during their approach and tapping the females prior to mounting. In our remating trials, none of the female D. scriptus accepted additional males after their first mating over the three-day period. In contrast, male D. scriptus were polygynous, often mating with multiple females. Across the trials, sexual size dimorphism was a predictor of whether mating occurred, with similarly sized pairs being more likely to mate. Additionally, previously mated females were less likely to cannibalize malesan unusual pattern for spiders. Like other species of Dolomedes Latreille, 1804, our results suggest a strong role of female aggression in D. scriptus mating system dynamics.
 
Article
Postmating cannibalism where a female attacks, kills and consumes a male after a sexual encounter is frequently influenced by certain male morphological and behavioral characteristics. We conducted behavioral assays in the laboratory to test the predictions that male Alpaida veniliae (Keyserling 1865) with larger absolute and relative size in relation to their mate and those having longer courtship and copulation duration would have lower probability of being cannibalized by females after a sexual encounter. We performed a set of mating trials exposing males of different sizes to virgin females. We observed copulation in 88.8% of mating trails; its duration was very brief compared to courtship. Only a few attempts (16.7%) of recopulations with the same female were recorded, and in all these cases the first copulation was significantly shorter than the mean copulation duration of those who had only one copulation. The percentage of postcopulatory cannibalism was 47.6%. There was no correlation between the relative and absolute male size and duration of courtship and copulation. Postcopulatory cannibalism was independent of courtship and mating durations but was affected by absolute and relative male size. Smaller males were more frequently cannibalized than large ones. However, it remains unclear whether sexual cannibalism in A. veniliae may be explained by female mate choice or whether smaller males are less able to escape or defend themselves. More studies are needed to understand the underlying factors of postcopulatory cannibalism of A. veniliae, as well as to elucidate their possible ecological and evolutionary implications.
 
Article
Vertical asymmetry is a widespread feature of orb webs, with the lower part larger than the upper, although its adaptive value is not fully understood. Gravity is thought to play a major role in the generation of asymmetry through increased running speed downwards from the hub. The relationship between spider orientation and gravity has been relatively well studied. However, webs' inclination from vertical has been less studied. Here we conducted a field study on the tetragnathid orb spider Metellina mengei Blackwall, 1869, which constructs webs that show a marked variation in inclination. Our findings revealed a significant influence of the degree of web inclination and web area on the level of vertical asymmetry, while environmental variables did not have any effect. Thus, our results support the hypothesis that the asymmetry in upwards and downwards running speeds due to gravity is an important determinant of web asymmetry. © 2018 American Museum of Natural History. All rights reserved.
 
Article
Little is known about reproduction in most cave spiders, including reproductive behaviors, seasonality, and fecundity. In the course of fieldwork in Tennessee caves, we observed aspects of reproduction in three populations of Liocranoides Keyserling, 1881 (Araneae: Zoropsidae) spiders. We observed egg sacs of L. archeri Platnick, 1999, as well as egg sacs and spiderlings of L. cf. gertschi Platnick, 1999. The spiders produced a spherical egg sac that hung from the cave ceiling by a single cord of silk. The egg sacs were covered by foreign material including sediment, rocks, and plant roots. Egg sacs were observed in June and July, and spiderlings were observed in July. Three egg sacs that were collected contained 26, 42, and 53 eggs. This is the first description of reproduction in Liocranoides. © 2018 American Museum of Natural History. All rights reserved.
 
Article
There are few works on the reproductive behavior of species of cribellate spiders. Even more scarce are studies of the reproductive behavior of representatives of the Desidae, such as the genus Metaltella Mello-Leit˜ao, 1931. In this paper, we describe for the first time the reproductive behavior of Metaltella iheringi (Keyserling, 1891), a species that is characterized by complex genitalia in both sexes. We determined frequencies and durations of the behaviors in the different phases. Thirty virgin males were exposed to virgin females and the behaviors performed by each sex, as well as their frequencies, were recorded. Three phases were identified: pre-copulatory, copulatory, and post-copulatory. The most frequent behaviors were chelicera-palp rubbing, abdomen vibration and web-stretching by the male, and body-shaking and leg-tapping on the web by the female. When the male grabbed the female, she typically fell into a state of quiescence (the female remained motionless with legs in a semi-flexed position) and she remained so even after the male ended the copulation. Mating was characterized by low aggression by the female and a low incidence of cannibalism. In the postcopulatory phase, the male performed frequent behaviors such as abdomen vibration, sperm induction, and postcopulatory cohabitation. We discuss the possible implications of these behaviors in a pre- and post-copulatory sexual selection context. We also provide information that serves as a basis for future studies to understand the mechanisms involved in these behaviors.
 
-Flowchart showing sequences of courtship and mating behavioral units in Parabatinga brevipes. The behaviors performed by the females are shown with ovals, male behaviors with rectangles, and combined male and female behaviors with dotted rectangles. Arrow thickness indicates the frequency of transitions. Asterisks indicate significant differences.
Article
Abstract. In spiders, intersex communication during courtship is essential to avoid the risks of cannibalism due to lack of specific recognition. Parabatinga brevipes (Keyserling, 1891) is a Ctenidae spider with a distribution from Colombia to Uruguay. This study is the first to describe the sexual behavior of P. brevipes, and the fourth reported in the family. We introduced males to females in a cage and recorded their courtship and copulation behavior. Males began courtship after touching female silk, performing Leg-tapping of legs I and Palpal movements. We observed ten copulations that usually occur vertically, in the copulatory position reported for other ctenids, with the male on top of the female, oriented in opposite directions. Copulations usually involve the insertion of one male palp in a single female’s genital opening and finish with the pair dropping from the vertical position. These sexual behaviors are compared with reports of other species in the family.
 
-Type localities of representatives of the Clubiona hystrix-group: 1. Clubiona analis Thorell 1895, Burma, Double Island; 2. Clubiona maipai Jä ger & Dankittipakul 2010, Thailand, Mae Hong Son Province, Ban Nam Rin; 3. Clubiona kuu Jä ger & Dankittipakul 2010, Laos, Luang Prabang Province, Ban Keng Koung; 4. Clubiona damirkovaci Deeleman-Reinhold 2001, Malaysia, Gombak Research Station.
-Clubiona analis Thorell 1895, holotype female from Burma, Double Island (right half of internal duct system damaged and omitted here). 1. Epigyne, ventral; 2. Vulva, dorsal; 3. Schematic course of internal duct system, dorsal (open circle -copulatory orifice, arrowfertilization duct in direction of the uterus externus.); 4. Eye arrangement, dorsal; 5. Right cheliceral furrow, ventral. Abbreviations: BU -bursa copulatrix, CD -copulatory duct, EP -epigynal pockets, FD -fertilization duct, SP -spermathecae, SS -slit sensilla.
Article
The holotype female of Clubiona analis Thorell 1895 is examined, illustrated, and redescribed. The systematic position of the species is discussed, and a map with the type locality together with those of related species is provided.
 
Article
The physiological effects of resource allocation due to dietary restriction in spiders are poorly understood; in fact, the system-wide effects of any environmental stresses on spider physiology remain relatively unstudied. The aim of this study was to show the consequences of dietary restriction in the pholcid spider Physocyclus mexicanus Banks, 1898. Male spiders were fed either a high (ad libitum) diet (n = 43) or low (5-8 Drosophila melanogaster/week) diet (n = 32) through their penultimate instar. We found significant differences in testis volume, body mass, and tibia-patella length TPL between the two groups. Linear regression analysis reveals that the differences in testis volume between the two groups are not solely due to differences in body mass; for any given body mass, the low diet group has a smaller mean testis size than the high diet group. Our results suggest that P. mexicanus males allocate resources away from testis volume in times of scarcity.
 
Article
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).
 
Article
Tengella perfuga Dahl, 1901 is a Nicaraguan cribellate zoropsid spider found in high altitude remnant cloud forest habitats bordering coffee plantations. Since its description in 1901, and its rediscovery in 2012, almost nothing is known of its natural history, life history, courtship or web spinning behavior. Observations were made in the field, as well as in the lab. Mature female T. perfuga occurred in funnel webs with several knockdown lines comprised of cribellate silk, and that were typically placed between buttress roots of strangler figs or other outcropping structures, while males abandoned their webs upon adulthood to search for females. Here, we describe the life history, growth, web ontogeny, courtship and reproductive behaviors, as well as silk use of this spider for the first time. There are 11-12 instars to reach adulthood and cribellate silk did not appear in juvenile webs until the eighth instar. Interestingly, orbicularian-like behaviors were observed in the initial appearance of cribellate silk lines in the juvenile web in a spiral-like pattern. Males exhibited positive allometric growth in Leg I from penultimate to adult instars, which likely plays an important role in courtship; this included strumming the sheet, stroking the female and depositing a thin 'bridal veil' of silk on the female. Virgin females had 'mating plugs' prior to exposure to males. This suggests that T. perfuga may be an interesting species with which to further examine sexual evolution and female choice.
 
Article
We characterize, in both the laboratory and the field, the preferential thermal microenvironments of Paraphysa párvula (Pocock 1903) (Araneae: Theraphosidae), a mygalomorph spider that successfully inhabits the high elevation environments of the Chilean Andes. We studied 116 spiders. Their average body temperature in the field was 31.02 ± 2.74°C, similar to the laboratory preferred temperature of 31.7 ± 2.31°C, and higher than the ideal temperature of reproductive females, 29.34 ± 2.81°C. In non-reproductive spiders, we found significant associations between body temperature and the temperatures of the air, substrate and rocks; however, the strongest association was between body and rock temperatures. Similar results were obtained in reproductive females, but there the best predictor of the body temperature was air temperature in the shelter. In both cases, the air temperature remained below body temperature and well below the temperature of the rocks and stones. Both situations show the importance of behavioral thermorégulation and the mechanisms of heat transfer into the microenvironment in the body temperature regulation of spiders. Conduction from the environment, heat transfer by small convection currents, and radiation from the hot stones constitute small environmental cues that allow these spiders to maintain an optimal temperature. The selection of shelters meeting specific temperature regimes appears to be a key condition for the optimization of female reproductive success and survival of females and juveniles in a high elevation environment.
 
Article
In the context of competitive mate searching, males may use cues from conspecifics, such as movement cues and/or courtship signals, to locate mates. For ground-dwelling wolf spiders, substrate-borne vibratory cues may be particularly important sources of information, given the potential presence of many visual obstacles. This study explores the possible use of conspecific male cues in wolf spiders by asking: (i) Do male Schizocosa retrorsa (Banks, 1911) wolf spiders use vibratory cues from conspecific males to alter their searching or signaling behavior? (ii) Can males assess the density of conspecific males using conspecific male cues? (iii) Does the variation in conspecific male density affect the behavioral response of focal males to the conspecific cues? To answer these questions, we tested the effects of (i) the number of conspecific males and (ii) the activity of conspecific males (e.g., courtship yes/no) on a focal male's behavior. We recorded the following focal male behavior: (a) the presence/absence of courtship behavior, (b) temporal/structural signal characteristics of the multimodal courtship signaling, and (c) locomotory patterns. Our results suggest that, (i) S. retrorsa males assess their competitive environment through substrate-borne vibratory cues generated by courting or non-courting behavior of conspecific neighbors, (ii) S. retrorsa males may alter their reproductive behavior between mate searching and courtship signaling by the assessment of cues associated with conspecific male density, and (iii) the assessment and perception of density-dependent conspecific courtship signaling can be used as social information to adjust the reproductive behavior.
 
Article
Of all scorpion species described to date, only a small fraction are known to reproduce without fertilization by a male, instead producing offspring by parthenogenesis. Here we show that isolated females of the buthid Pseudolychas ochraceus (Hirst, 1911) are capable of parthenogenetic reproduction and we provide data on the postembryonic growth of this species.
 
Article
Arachnida evolved different reproductive strategies in the terrestrial habitats. Knowledge of the morphology of reproductive systems varies depending on the group, and for Opiliones only a few studies exists addressing this topic. Here, we describe the morphology of the male reproductive tract and the spermatozoon of the harvestman Mischonyx cuspidatus (Roewer, 1913). In this species, males have a single testis, a pair of deferent ducts, a seminal vesicle, a propelling organ and a penis. The lumen of the folded seminal vesicle and testis follicles are filled with spermatozoa, suggesting a storage of sperm related to a possible reproductive strategy involving multiple matings. The spermatozoa are aflagellate and ca. 6.5 µm in length. This study sheds light on the knowledge of the harvestman's reproductive biology and life strategy, which can be used in future studies involving Opiliones behavior and systematics.
 
Article
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.
 
Article
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.
 
Article
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.
 
— Tangaroa vaka n. sp. a. female, dorsal view; b. male, dorsal view; c. femur IV, calamistrum, prolateral view, female; d. carapace, lateral view, male; e. femur I, distal crook (arrow), retrolateral view. Scale bars: a, b. 1 mm; c, d. 0.2 mm; e. 0.5 mm. 
-a-c. Tangaroa vaka n. sp., female, epigynum. a. Ventral view; b. cleared, dorsal view; c. dorsal view. d-f. Tangaroa pukapukan n. sp., female, epigynum. d. Ventral view; e. cleared, dorsal view; f. dorsal view. Scale bars: a, 0.3 mm; b, c, e, f, 0.1 mm; d, 0.2 mm.
— Tangaroa vaka n. sp., palp. a. Prolateral view; b. retrolateral view; c. dorsal view; d. ventral view; e. frontal view. Scale bars, 0.2 mm. 
— Tangaroa pukapukan n. sp. a. Dorsal view, female; b. dorsal view, male; c. femur IV, calamistrum, prolateral view, female; d. carapace, lateral view, male; e. femur I, distal crook (arrow), retrolateral view. Scale bars: a, b, 1 mm; c, d, 0.2 mm; e, 0.5 mm. 
— Tangaroa pukapukan n. sp., palp, cleared. a. Prolateral view; b. retrolateral view; c. dorsal view; d. ventral view; e. frontal view. Scale bars: a–e, 0.2 mm. 
Article
Two new species of Tangaroa Lehtinen 1967 (Araneae: Uloboridae) from the Cook Islands are described here: Tangaroa vaka n. Sp. from Rarotonga, and Tangaroa pukapukan n. Sp. from Mitiaro, both based on male and female specimens.
 
Article
The troglobitic harvestman Jimeneziella decui Avram, 1970 is known from four neighboring caves (Cueva de Majana, Cueva de los Golondrinos, Cueva Perla del Agua, and Cueva de Mximo) located in eastern Cuba. We present the first ecological data on a population of this endangered species in Cueva de Mximo. The sex ratio of the population estimated in the main gallery of the cave was not different from 1:1. The spatial distribution observed was uniform, and the density of individuals was 0.48 individuals/m2 (FebruaryMarch) and 0.84 individuals/m2 (November). We describe morphological differences between the sexes and between males. Preliminary morphological and behavioral data suggests the possible existence of two male morphs in J. decui (robust and slender males). The slender males possessed less developed armature on leg IV; and the chelicerae, coxa IV and femur IV were less swollen than robust males. Our observations on male-male interactions suggest that robust males are more aggressive than slender males, which never initiated an attack on robust males, but in some occasions responded to attacks from robust males. The non-aggressive behavior exhibited by robust males towards slender males also suggests that the slender morph is not only a sneaker, but potentially a female mimic, which is also consistent with the morphology of slender males. Ecological and behavioral information also suggests the possible existence of territories defended by robust males with their well-developed weapons, and the presence of females inside them.
 
Article
The hymenopteran genus Zatypota Forster, 1869 (Ichneumonidae: Pimplinae, Ephialtini) comprises highly specialized koinobiont ectoparasitoids of spiders and is the largest genus of the Polysphincta group of genera in the world, with more than 50 described species. The vast majority of species of Zatypota are parasitoids of the spider family Theridiidae. In this study, we present information about a new interaction between the parasitoid spider wasp Zatypota riverai Gauld, 1991 and the host spider Theridion sp. Walckenaer, 1805 (Theridiidae) with information about host weight selection. We collected 102 non-parasitized adult and subadult females of Theridion sp. and six spiders with larvae of Z. riverai attached to host’s abdomen. The pupal development takes about 8–11 days, though the development time of the pupa varies with the sex of the wasp. All larvae collected in the field completed their life cycle on the host spiders, even though all of the hosts were small, indicating that the host biomass was sufficient for larval development and no largersized spiders are needed. Moreover, larger Theridion probably pose a greater risk because they are more likely to be successful at wasp predation, even if they offer a greater resource to the larva.
 
Article
Since its original description, the theraphosid spider genus Crassicrus Reichling and West, 1996 has not been revised and no new species have been described. While reviewing material deposited in the Mexican National Collection of Arachnids (National Autonomous University of Mexico, Mexico City) and the American Museum of Natural History (New York, USA), we encountered specimens corresponding to four new species of Crassicrus from Mexico. In this revision, we include a redescription of the genus and its type species, C. lamanai Reichling and West, 1996, and describe four new species: C. bidxigui, C. tochtli, C. cocona, and C. yumkimil. Species habitat data are provided, as well as identification keys for males and females. In addition, new keels on the male embolus were identified and are described. In the Theraphosinae, the presence of one retrolateral keel has been reported, but in Crassicrus, there are two or three retrolateral keels, and a new taxonomical nomenclature for these keels is proposed. The genus Crassicrus is recorded from Mexico for the first time, increasing the number of known theraphine genera in the country to 16.
 
-Cercophonius himalayensis, holotype male: a. Habitus, dorsal aspect under visible light; b. Habitus, ventral aspect under visible light; c. Metasomal segment V and telson, lateral aspect under UV light; d. Metasomal segments I-III, ventral surface, under UV light; e. Telotarus III, ventral surface under visible light; f. Pedipalp chela, ventrointernal surface under visible light; g. Metasomal segment V, ventral surface under UV light; h. Pedipalp chela, detail of fingers from dorsal view under visible light. Scale bars: a, b: 0.2 mm; c-h: 1 mm.
-Cercophonius himalayensis, holotype male: a. Left hemispermatophore, internal surface under visible light; b. Left hemispermatophore, external surface under visible light; c. Left chelicera, dorsal aspect under UV light; d. Detail of distal lamina of hemispermatophore, external aspect under UV light. Scale bars: 0.5 mm.
-Cercophonius michaelseni, male (from Tammin, Western Australia, MACN-Ar): a. Detail of distal lamina of hemispermatophore, external aspect under UV light; b. Detail of the internal surface of the movable finger of left pedipalp chela under UV light; c. Detail of the ventral surface of telotarsus III under UV light; d. Metasomal segment V, ventral surface, under UV light. e-h. Phoniocercus sanmartini, male (from Chacao, Chiloe Island, Chile, MACN-Ar): e. SEM image of ventral surface of telotarsus IV; f. Detail of distal lamina of hemispermatophore, external aspect under UV light; g. Ventrointernal surface of right pedipalp chela under UV light; h. Ventral surface of metasomal segments under UV light. Scale bars: a, c, e, f: 0.3 mm; b, d, g, h: 1 mm.
Article
We studied the male holotype of Cercophonius himalayensis Lourenço, 1996, the sole member of the scorpion family Bothriuridae from India, and concluded that it belongs to a species of the genus Phoniocercus Pocock, 1893, which is endemic to the temperate forests of Patagonia. The presence of a Patagonian genus in India is extremely unlikely; therefore, we consider this to be a case of mislabeling of the specimen, and consequently exclude the scorpion family Bothriuridae from Indian fauna. Cercophonius himalayensis is transferred to the genus Phoniocercus, and formally synonymized with Phoniocercus sanmartini Cekalovic, 1968. A brief illustrated description of the type specimen is made, emphasizing important diagnostic characters and some body parts not previously described, such as the hemispermatophore. We also present a probable explanation for the origin of the material. © 2018 American Museum of Natural History. All rights reserved.
 
Article
Four new species of Xenocytaea: X. stanislawi, X. taveuniensis, X. victoriensis, and X. vonavonensis are described from Fiji and the Solomon Islands. X. anomala Berry et al. 1998 is excluded from the genus. The remarks on distribution and relationships are compared with literature data.
 
-Rishaschia mandibularis: a. Male from Juruti, Para´,Para´, Brazil, dorsal view. b. Same, ventral view. c. Same, lateral view (left palp and legs removed). d. Female from same locality, dorsal view. e. Same, ventral view. f. Same, lateral view (left palp and legs removed).
-Rishaschia mandibularis: a. Male chelicerae (holotype of Asaracus roeweri Caporiacco), ventral view. b. Left male palp (holotype of Asaracus roeweri Caporiacco), ventral view. c. Same, lateral view. d. Left male palp, dissected bulb, cleared, ventral view. e. Epigyne, ventral view. f. same, cleared, ventral view.
-Rishaschia mandibularis, left male palp, ventral view: a-i. Specimens from Juruti, Para´,Para´, Brazil, showing variation in embolus length and position of sperm duct. a. MPEG 21106. b. MPEG 21107. c. MPEG 21108. d. MPEG 21109. e. MPEG 21110. f. MPEG 21111. g. MPEG 21112. h. MPEG 21113. i. MPEG 21114. j. Same, retrolateral view. k. Male holotype of Attus mandibularis Taczanowski. l. Male syntype of Attus cabanisi Taczanowski.
Article
Attus mandibularis Taczanowski, 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.
 
-Primers used for detection of five endosymbiont genera. 
-Sex ratio data and endosymbiont infection status grouped by matriline. 
-Phylogenetic position of the Rickettsia (partial citrate sequence) endosymbiont of Oedothorax retusus [GenBank: JN889707]. Terminal taxa represent host species. A p-distance based neighbor joining tree was constructed as implemented in MEGA 5 (Tamura et al. 2011) on a subset of Rickettsia sequences available at GenBank. Percentage bootstrap support was calculated for the nodes. Genbank accession numbers are given in front of the taxonomic group to which the host species belongs. Sequences that originate from spider hosts are underlined. Oedothorax retusus is shown in bold. 
-Relationship between number of adult offspring and proportion of male offspring in the egg sac. Open circles: Wolbachia and Ricketssia-infected females, filled circles: Wolbachia and Ricketssia-uninfected females. The solid line visualizes the linear correlation. 
-Clutch size number produced by Wolbachia and Rickettsia infected (black bars) and uninfected (grey bars) females in first egg sacs (after hatching, number of spiderlings) and second and third egg sacs (before hatching, number of eggs). Bars with the same letter annotation indicate values that are not significantly different. 
Article
Spiders exhibit a remarkable variety of reproductive phenotypes such as induced parthenogenesis and reproductive skew in primary sex ratio. However, observations of distorted sex ratios are mainly inferred from field catches of adult individuals, whereas detailed information on clutch primary sex ratio and sex ratio inheritance, resulting from multiple generations of laboratory rearing, is scarce. One of the potential causes of sex ratio variation is infection with maternally inherited endosymbiont bacteria that alter a mother's offspring sex ratio to increase their own fitness. Although studies show that spiders are infected with several endosymbiont species, it was only recently discovered that endosymbiont bacteria can cause a female sex ratio bias in this order. To explore the distribution of biased sex ratios and endosymbiont infection patterns, we investigated sex ratio variation and bacterial presence in Oedothorax retusus Westring 1851. Significant sex ratio variation was detected in six matrilines originating from wild-caught females, one of which consistently showed a female bias in offspring production. Congruent with a bacterial effect, the sex ratio bias showed a clear maternal inheritance, and treatment with antibiotics reversed the sex ratio to equal numbers of males and females. Female-biased clutches were found to exhibit a significantly lower number of hatched spiderlings than unbiased clutches, suggesting the occurrence of male-killing. All matrilines showed infection with the Cardinium endosymbiont, while two matrilines, including the female biased one, were additionally infected with Wolbachia and Rickettsia. These findings indicate that bacterial endosymbionts are responsible for the sex ratio variation in this species, and suggest that effects of endosymbiont bacteria in the order Araneae could be more widespread than previously assumed.
 
Article
Although spiders are common inhabitants of tree cavities, factors that drive their community structure in these microhabitats are little known. Here we investigated whether bark type, season, intraguild predation (IGP) among spiders, and presence of vertebrate predators can influence the spider community structure in tree cavities. We examined spider abundance and the taxonomic and functional composition of spiders in nest-boxes within two mixed forest stands in central Slovakia in 2012–2013. In total, 1211 spiders belonging to 31 species were sampled from 60 nest-boxes at two sites over three seasons. Spider abundance peaked in autumn as spiders sought wintering sites. Guilds and taxonomic composition changed seasonally with spring and autumn communities dominated by ‘‘Other hunters’’ (Anyphaenidae, Clubionidae, Philodromidae) while during summer the community was dominated by ‘‘Sheet web weavers’’ (Linyphiidae). The guild and taxonomic turnover may be partly explained by the interaction between spiders’ phenology and IGP exerted by winter-active spiders on smaller spiders from autumn until spring. Bark type influenced the guild composition as dominance of ‘‘Space web weavers’’ was higher in trees with rough bark than in trees with smooth bark. The rough bark also reduced the intensity of IGP by Anyphaena accentuata (Sundevall, 1833) on philodromids. The presence of insectivorous birds reduced the abundance of spiders by 67%. The presence of bird predators altered the guild composition as they affected mostly the web spiders. The results show that the biotic interactions and abiotic factors interactively determined the spider community structure in the nest-boxes depending on spiders’ functional traits.
 
Article
We investigated the influence of burning frequency and timing on the abundance and diversity of cursorial arachnids in the cerrado (savannah of central Brazil). Five areas were subjected to different burning regimes. In each area, 40 pitfall traps were installed. The arachnids were sampled for three days each month from April 2007 to October 2008. Abundance was higher in the control area than in areas subjected to any fire regime. Species richness was similar in all areas. The evenness was lower in the control area. The areas subject to fires had significantly higher diversity than the control area. Although it was not possible to rank areas according to their diversity, areas burned in the middle of the dry season tended to have higher diversity than areas burned at the beginning or end of this season, indicating that the time at which fire occurs may be more important than the frequency of burning for the diversity of cursorial arachnids in the Brazilian cerrado.
 
Article
We compared the abundance of spiders and predaceous insects in five central California vineyards. Spiders constituted 98.1% of all predators collected. More than 90% of all spiders collected were from eight species of spiders, representing six families. Two theridiids (Theridion dilutum and T. melanurum) were the most abundant, followed by a miturgid (Cheiracanthium inclusum) and an agelinid (Hololena nedra). Predaceous insects comprised 1.6% of all predators collected, and were represented by six genera in five families. Nabis americoferis (Heteroptera, Nabidae) was the most common predaceous insect, with its densities highest late in the growing season. Chrysoperla carnea, Chrysoperla comanche and Chrysopa oculata (Neuroptera, Chrysopidae) and Hippodamia convergens (Coleoptera, Coccinellidae) were most abundant early in the season. The dominance of spiders may be due to their more stable position in the vineyard predator community compared to predaceous insects. We also suggest that the low percentage of predaceous insects (e.g., lacewings) may reflect the lack of preferred prey (e.g., aphids) on grapevines.
 
Article
Absence of light is a fundamental characteristic of subterranean ecosystems; thus, productivity must be supported indirectly by influx of detritus from effulgent environments. I examined how this influx impacts the carrying capacity of a cave predator: the whip spider Phrynus longipes (Pocock, 1894). Although solitary, territorial and cannibalistic, this species occurs at extremely high densities in caves. To test the hypothesis that this is an effect of nutrient flow and not cave structure, I examined whether guano deposition at cave entrances predicted estimated population sizes of whip spiders. I found a strong correlation, suggesting that whip spider carrying capacities are at least partly determined by nutrient influx to the cave ecosystem. Larger guano deposits support a larger community of arthropod detritivores, which act as prey to this top predator in a bottom-up effect. This highlights the importance of considering surface environmental and population health along with commercial guano harvesting when studying and conserving caves and the species therein.
 
Top-cited authors
Mark Stephen Harvey
  • Western Australian Museum
Stano Pekar
  • Masaryk University
George W Uetz
  • University of Cincinnati
Ferenc Samu
  • Centre for Agricultural Research (previously research institute of the Hungarian Academy of Sciences)
Fernando Pérez-Miles
  • Universidad de la República de Uruguay