Plant structure specialization in Paraphidippus basalis (Araneae: Salticidae), a jumping spider of the Madrean Sky Islands
Agave, Arizona, microhabitat, sotol, yucca
Paraphidippus basalis (Banks, 1904) is a large jumping spider that occurs in the sky islands of the southwestern United States and northern Mexico. To date, P. basalis has only been incidentally reported on rosette-forming plants in the family Asparagaceae (yucca, agave, and sotol), even though the sky islands support a rich and diverse vegetation community. This apparent specialization is unusual because jumping spiders do not typically have strong associations with the plants on which they live. However, given that the ecology of P. basalis has yet to be studied, the microhabitat preferences of P. basalis remain unclear. We investigated microhabitat choice in P. basalis in the Patagonia Mountains of southeastern Arizona, to determine whether these spiders were specifically associated with rosette-forming plants. We surveyed 160 plots for jumping spiders, 80 with rosette-forming plants and 80 without. P. basalis was found only in rosette- forming plants, whereas other species of jumping spiders showed no preference for rosette or control plots. Larger rosette plants were more likely to contain P. basalis. This study provides an unusual example of host plant structural specificity in a jumping spider.
Sub-units in the webs of Dictyna meditata (Arachnida: Araneae: Dictynidae): implications for studies of spider web evolution
Phylogeny, behavioral modules, combing behavior, categorizing web designs
Studies of web evolution in spiders generally focus on the overall designs of webs in the field. As has been typical for dictynids and several other cribellate families with ‘‘irregular’’ webs, this study detected few discernable patterns in the field regarding the spatial organization of the highly variable, three-dimensional and largely aerial webs of the dictynid Dictyna meditata Gertsch, 1936. Nevertheless, there were three consistent sub-unit designs in the additions that spiders made to their webs in captivity, and in webs that they built from scratch in captivity: ‘‘silk ladders’’, with a cribellum line that zig-zagged between a pair of approximately parallel non-sticky lines; ‘‘twig ladders’’, with a cribellum line that zig-zagged between a non-sticky line and the substrate; and long non-sticky lines that each supported a long, slightly looped cribellum line. I suggest, using examples from dictynids and other families with long-lived, geometrically irregular webs, that this pattern of using consistent behavior patterns to add geometrically regular ‘‘modules’’, is widespread and ancient, but has often been missed due to damage and additions to webs in the field, and to lack of direct behavioral observations. Recent attempts to link web evolution to studies of spider phylogeny could benefit from a change of emphasis, focusing on the additions that spiders make to their webs, rather than on the currently common but necessarily vague characterizations of overall web designs seen in the field.
Asexual reproduction in a sexual population of the Brazilian yellow scorpion (Tityus serrulatus, Buthidae) as evidence of facultative parthenogenesis
geographic parthenogenesis, sex ratio, sexual reproduction
Most Brazilian yellow scorpion (Tityus serrulatus Lutz & Mello, 1922) populations reproduce by parthenogenesis, and only a few sexually reproducing populations are known. It has been suggested that the parthenogenesis in T. serrulatus is related to bacterial endosymbionts, but this hypothesis was recently refuted, so the causes of parthenogenesis in this species are still unknown. In the present study, we report parthenogenetic reproduction in females from a sexual population, either isolated in laboratory since birth or collected at juvenile stages. Twelve females collected as juveniles became adult and reproduced without contact with males (thus, through parthenogenesis) in the laboratory. Five females collected already pregnant gave birth to litters (F1) composed only of females, which is suggestive of parthenogenesis in the field. Eight F1 females from those litters subsequently reproduced by parthenogenesis in the laboratory. Another female collected already pregnant gave birth to a litter composed of males and females (F1), indicating sexual reproduction in the field. However, one F1 female from that litter reproduced by parthenogenesis in the laboratory. These results suggest that asexual reproduction is facultative in this population.
Characterization of antibacterial activities of hemolymph from the desert hairy scorpion, Hadrurus arizonensis
Arachnid, arthropod, immunology, innate immunity
Treatment of bacterial cultures with hemolymph collected from desert hairy scorpions (Hadrurus arizonensis Ewing, 1928, Hadruridae) resulted in a time- and concentration-dependent inhibition of bacterial proliferation. The hemolymph proved effective in inhibiting growth of both Gram-negative and Gram-positive bacterial species. Incubation of E. coli bacteria with hemolymph at different temperatures (20–408C) showed that the antibacterial effects increased from 20–308C, but the hemolymph was largely ineffective in killing the bacteria at 35 and 408C. Incubation of E. coli with hemolymph at 258C for different time periods revealed that the antibacterial activities were extremely rapid and resulted in killing of bacteria within 1–2 minutes of contact. Interestingly, the hemolymph exhibited no phenoloxidase enzyme activity, hemolytic activity against sheep red blood cells, or melanization activity, which is a common mechanism of immunity among many diverse arthropods. This study is the first characterization of immune function of hemolymph from any scorpion species.
Mating behavior of Dactylochelifer latreillii latreillii (Pseudoscorpiones: Cheliferidae): A quantitative study
Mating dance, courtship, ram’s horn organs, spermatophore
The arachnid order Pseudoscorpiones is characterized by a huge number of different mating strategies. Cheliferidae, for instance, have developed complex mating dances, including the use of the curious ram’s horn organs of males. The present study provides a detailed description of the mating behavior of Dactylochelifer latreillii latreillii (Leach, 1817), including first quantitative data for each behavioral unit, based on the analysis of laboratory video captures of individual mating ceremonies. Previous studies on mating in cheliferids have been purely qualitative, including a description of mating in a distinct subspecies of D. latreillii, D. l. septentrionalis Beier, 1932. Qualitatively, our data on Dactylochelifer l. latreillii is roughly consistent with these older observations except for some differences in the vibrating behavior of males.
Phylogeography of Neopurcellia salmoni, a widespread mite harvestman from the South Island of New Zealand, with the first report of male polymorphism in the suborder Cyphophthalmi (Arachnida: Opiliones)
Intrasexual polymorphism, alternative reproductive tactic, population genetics, species delimitation, Pettalidae
Neopurcellia salmoni Forster, 1948 is a mite harvestman found throughout the forests of the west coast of New Zealand’s South Island. This species range is unusually large for the notoriously dispersal-limited Cyphophthalmi, raising the possibility of multiple cryptic species within the lineage. In order to test this hypothesis, we used scanning electron microscopy to examine a large number of individuals from throughout its range, and discovered two distinct male morphotypes distinguished by the presence or absence of dorsal glandular pores. We performed phylogeographic and population genetic analyses using DNA sequence data from the fast-evolving mitochondrial locus cytochrome c oxidase I (COI). Tree topologies revealed two well-supported clades within Neopurcellia Forster, 1948 occupying non-overlapping geographical regions of the west coast. Molecular dating indicates that these lineages diverged from each other following the Oligocene ‘‘drowning’’ of New Zealand and diversified during the uplift of the Southern Alps. The strong correlation between the evolutionary relationships of lineages within Neopurcellia and the geographic distribution of its populations indicates isolation by distance, as expected with dispersal-limited organisms; population genetic analyses confirm strong isolation of populations. However, we discovered that the distribution of male morphotypes does not follow any geographic or phylogenetic pattern. While the presence of two different morphotypes initially suggested multiple Neopurcellia species, phylogeographic analysis allowed us to reject this hypothesis. We therefore report here the first known case of male polymorphism in the suborder Cyphophthalmi.
On the harvestmen species described by Gray in Cuvier’s Animal Kingdom (Opiliones: Eupnoi, Laniatores)
Zoological nomenclature; Arachnida; Caelopyginae; Goniosomatinae
The English counterpart of Cuvier’s Le Re`gne Animal, organized by Edward Griffith in several volumes, contained not only a translation of the French original, but also new material added by invited collaborators. The part on Arachnida, with new material contributed by George R. Gray, contained descriptions of five species of Opiliones, one of them a mite, and two of them new. There are identifications, synonymies and homonymies involved in the taxonomy of these species which are questioned herein. Gonoleptes spinipes Gray, [20 July] 1833 is a senior primary homonym of Gonyleptes spinipes Perty, [13 December] 1833. This is currently a species inquirenda in Caelopyginae, which is newly considered a subjective synonym of Metarthrodes triangularis Roewer, 1931. The latter name should stand in virtue of the senior being invalid by homonymy. Gonoleptes spinipes Gray is also a new subjective synonym of Goniosoma roridum Perty, 1833, which is in prevailing usage, which makes it a nomen protectum.
Discovery of the genus Eukoenenia (Palpigradi: Eukoeneniidae) from China and description of a new species
Taxonomy, chaetotaxy, edaphic fauna.
A new species, Eukoenenia sinensis, is described and illustrated from specimens collected in two forests in nearby islands in Guangdong Province, Southeast China. The genus Eukoenenia is recorded for the first time from China and it represents the second palpigrade species reported for this country after Koeneniodes madecassus Re ́my, 1950. The new species shares several morphological characters with other soil-dwelling Eukoenenia species from Africa, Asia and South America. One of the distinctive characters of E. sinensis is the presence of 6 pairs of setae (a1, a2, a3, a4 þ s1, s2) on opisthosomal sternites IV to VI, a character only shared with another five species. Eukoenenia sinensis is most similar to specimens captured from Chile and identified by Dr. Bruno Conde ́ as Eukoenenia cf. grassii; several morphological and morphometric features allow to differentiate both species. From the other four species, two can be readily distinguished by their troglomorphic characters, and the other two are soil-dwelling species that show differences in the chaetotaxy of basitarsus IV, metapeltidium, deutotritosternum, opisthosomal tergites III–VI, as well as the number of teeth in the cheliceral fingers. In addition, E. sinensis is the first palpigrade to exhibit sexual dimorphism in the number of thick setae of coxa IV.
Elemental enrichment of the exoskeleton of the whip spider Phrynus marginemaculatus (Arachnida: Amblypygi)
Transition metals, chelicerate, enrichment, whip spiders, SEM-EDS
Amblypygi is a small order of arachnids that includes the whip spiders. Like other members of the clade Pedipalpi, these arachnids are cryptic predators that use their antenniform appendages to detect prey, and spinose pedipalps for quick prey capture. To date, there is very little information on the composition of their exoskeleton despite its importance in predation and defense. Here, we performed the first analysis of a whip spider exoskeleton using energy- dispersive X-ray spectroscopy (SEM-EDS). Our studies of Phrynus marginemaculatus CL Koch, 1840 were designed to (1) determine if elemental profiles differ between instars and (2) determine if and how elemental profiles of whip spiders differ from other closely related arachnids. We found the whip spider exoskeleton to contain several trace metal elements including calcium, magnesium, manganese, potassium, sodium, and zinc. The diversity and abundance of trace elements is relatively low throughout the exoskeleton of 2nd instars but increases in adults. In particular, the chelicerae and pedipalps are well reinforced with several metal elements, most notably calcium and zinc, which are also present in the tarsal claws. A similar elemental distribution is known for adult whip scorpions (Thelyphonida). In P. marginemaculatus, these metal elements are similarly present in adult exuviae. The elemental enrichment of the whip spider exoskeleton is comparable to that present in other members of the Pedipalpi and Tetrapulmonata, reflecting a relatively conserved profile for the few species that have been examined.
Zombie spiders and ecdysone: manipulation of Allocyclosa bifurca (Araneae: Araneidae) behavior by a parasitic wasp
behavioral manipulation, molting hormone, Ichneumonidae
In previous studies, the ‘‘cocoon’’ webs built by spiders of the genera Cyclosa Menge, 1866 and Allocyclosa Levi, 1999 under the influence of Polysphincta spp. wasps resembled molting webs built by unparasitized spiders; this behavioral manipulation was associated with increased concentrations of the molting hormone ecdysone. The present study documents an additional aspect of the cocoon webs of Allocyclosa bifurca (McCook, 1887) built under the influence of the wasp Polysphincta gutfreundi Gauld, 1991. Molting webs were more likely to have an associated barrier web than were prey capture orbs; and cocoon webs were even more likely to have barrier webs. The similarity between molting and cocoon webs accords with previous indications of ecdysone use by the wasps. The accentuation of molting web traits in the cocoon webs (also seen in other species) implies that the wasps manipulate the spiders using mechanisms other than simply replicating hormonal stimuli involved in normal molting.
Field observations on consumption of fermented tree sap by spiders in deciduous forests in Japan
Alternative food resource, Castanea crenata, phenology, plant-eating, Quercus serrata
Accumulated studies have revealed that spiders, which are believed to be true predators, also feed on various plant materials such as pollen, nectar, and stigmatic exudate. Hereby, we report observational cases of fermented tree sap feeding by four spider species, namely Sinopoda forcipata (Karsch, 1881) (Sparassidae), Otacilia komurai (Yaginuma, 1952) (Phrurolithidae), Weintrauboa contortipes (Karsch, 1881) (Pimoidae), and Doenitzius cf. peniculus Oi, 1960 (Linyphiidae), in deciduous forests in Japan. This is the first report of spiders feeding on fermented sap, and also the first report of plant material consumption in the families Sparassidae, Phrurolithidae, and Pimoidae.
No strings attached: description of the sexual behavior in the Neotropical spider Parabatinga brevipes (Keyserling, 1891) (Araneae: Ctenidae)
Courtship, copulation, male silk-laying, spiderlings
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.
Males respond to substrate-borne, not airborne, female chemical cues in the jumping spider, Habronattus pyrrithrix (Araneae: Salticidae)
Salticidae, chemical ecology, sexual selection, mate searching
Jumping spiders are known for complex courtship displays with both visual and vibratory components, but increasing evidence shows they also use chemoreception in intraspecific communication. We conducted two experiments using Habronattus pyrrithrix (Chamberlin, 1924) to assess male response to substrate-borne or airborne chemical cues produced by virgin females. First, we tested the effect of substrate-borne cues by allowing males to inspect two pieces of filter paper that had either been exposed to a female (thus covered in silk and/or excreta) or not (control). Second, we used a Y-tube olfactometer to test male response to female airborne cues versus a no-odor control in the absence of substrate- borne cues. Males responded to substrate-borne cues (spending more time traversing and palpating female-treated filter paper compared with the control) but did not respond to airborne cues alone. Together, these experiments suggest male H. pyrrithrix may use contact chemical cues from female silk to locate or assess females.
Fundamental trophic niche of two prey-specialized jumping spiders, Cyrba algerina and Heliophanus termitophagus (Araneae: Salticidae)
Araneophagy, diet breadth, prey acceptance, specialization, termitophagy
Spiders are among the most taxonomically diversified orders of predators, but data on the trophic niche of most species are still unknown. Here, we investigated the fundamental trophic niche of two species of jumping spiders, Cyrba algerina (Lucas, 1846) and Heliophanus termitophagus Wesołowska & Haddad, 2002, for which data on their realized trophic niche suggest trophic specialization (feeding on other spiders or termites, respectively). We investigated their fundamental trophic niche by means of acceptance experiments. Both species accepted a broader spectrum of prey under laboratory conditions than in the field, suggesting they are euryphagous specialists.
Morphology of the male reproductive tract of the harvestman Mischonyx cuspidatus (Roewer, 1913) (Gonyleptidae: Opiliones: Chelicerata)
Arachnida, aflagellate spermatozoa, Laniatores, reproduction.
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 lm 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.