Atypus karschi Dönitz, 1887 (Araneae: Atypidae): an Asian purse-web spider established in Pennsylvania, USA

The Mygalomorph spiders of the family Atypidae are among the most archaic spiders. The genus Atypus Latreille, 1804 occurs in Eurasia and northern Africa, with a single enigmatic species, Atypus snetsingeri Sarno, 1973, restricted to a small area in southeastern Pennsylvania in Eastern USA. This study was undertaken to learn more about genetics of that species, its habitat requirements and natural history. A close relationship to European species could be assumed based on A. snetsingeri’s occurrence on the eastern coast of the USA, however molecular markers (CO1 sequences) confirmed that A. snetsingeri is identical with Atypus karschi Dönitz, 1887 native to East Asia; it is an introduced species. The specific epithet snetsingeri is therefore relegated to a junior synonym of A. karschi . The karyotype of A. karschi has 42 chromosomes in females and 41 in males (X0 sex chromosome system). Chromosomes were metacentric except for one pair, which exhibited submetacentric morphology. In Pennsylvania the above-ground webs are usually vertical and attached to the base of bushes, trees, or walls, although some webs are oriented horizontally near the ground. It was found in a variety of habitats from forests to suburban shrubbery, and over a wide range of soil humidity and physical parameters. Prey include millipedes, snails, woodlice, carabid beetles and earthworms. The number of juveniles in excavated female webs ranged from 70 to 201. Atypus karschi is the first known case of an introduced purse-web spider. It is rarely noticed but well-established within its range in southeastern Pennsylvania.

Shaped by the Sun: the effect of exposure to sunlight on the evolution of spider bodies

Body temperature can strongly influence fitness. Some Sun-exposed ectotherms thermoregulate by adjusting body posture according to the Sun's position. In these species, body elongation should reduce the risk of heat stress by allowing the exposure of a smaller body area to sunlight. Therefore, selection should favour more elongated bodies in Sun-exposed than in Sun-protected species. Diurnal orb-web spider species that sit on their webs are more likely to be Sun-exposed, on average, than nocturnal or diurnal shelter-building species. We measured the body elongation of orb-web spiders (Araneae, Araneidae) across 1024 species and classified them as Sun-protected or exposed based on the literature. We found that Sun-exposed species evolved more elongate bodies than Sun-protected ones. Further, we built a model combining traditional heat transfer models with models of thermoregulatory postures in orb-web spiders and meteorological data. The model indicates that body elongation in large orb-web spiders decreases the risk of high body temperatures. Overall, our results suggest that Sun exposure influenced the evolution of body shapes of orb-web spiders.

Three species of hackled-orb web spider genus Miagrammopes from China (Araneae, Uloboridae)

Three species of the genus Miagrammopes O. Pickard-Cambridge, 1870 are described from China, including two new species, M. rutundus Liang & Xu, n. sp. from Guangxi Zhuang Autonomous Region and M. auriculatus Cai & Xu, n. sp. from Tibet Autonomous Region, and one known species, M. bifurcatus Dong, Yan, Zhu & Song, 2004. The female of M. bifurcatus is described for the first time. Both detailed illustration and a distribution map of the three species are provided.

Capture silk scaffold production in the cribellar web spider

Spider capture silk is a natural scaffolding material that outperforms most synthetic materials in terms of its combination of strength and elasticity. Among the various kinds of silk threads, cribellar thread is the most primitive prey-capturing type of spider web material. We analyzed the functional organization of the sieve-like cribellum spigots and specialized calamistral comb bristles for capture thread production by the titanoecid spider Nurscia albofasciata. The outer cribellar surface is covered with thousands of tiny spigots, and the cribellar plate produces non-sticky threads composed of thousands of fine nanofibers. N. albofasciata cribellar spigots are typically about 10 μm long, and each spigot appears as a long individual shaft with a pagoda-like tiered tip. The five distinct segments comprising each spigot is a defining characteristic of this spider. This segmented and flexible structure not only allows for spigots to bend individually and join with adjacent spigots, but it also enables spigots to draw the silk fibrils from their cribella with rows of calamistral leg bristles to form cribellar prey-capture threads.

Capture Silk Scaffold Production in the Cribellar Web Spider

Spider capture silk is a kind of natural scaffold material that outperforms almost any synthetic material in its combination of strength and elasticity. Among the various kinds of silk threads, the cribellar thread is the most primitive type of prey-capturing thread found in spider webs. We analyze the functional organization of the sieve-like cribellum spigots and a specialized comb bristles of calamistrum for capture thread production in the titanoecid spider Nurscia albofasciata. It's outer surface of the cribellum is covered with thousands of tiny spigots, and this cribellum plate produces the non-sticky threads which composed of thousands of finest nanofibers. Average length of the cribellum spigot in N. albofasciata is 10 µm, and each cribellate spigot appeared as singular, long shafts with pagoda-like tiered tips. Each spigot has five distinct segments as a definitive characteristic of this spider. This segmented and flexible structure not only allows it to bend by itself and join together with adjacent spigots, but also enable to draw the silk fibrils from its cribellum with a row of leg bristles of calamistrum to form a cribellar prey capture thread.

A ghost in the salt: A new species of halotolerant tube-web spider in the genus Ariadna (Araneae: Segestriidae)

A new species of halotolerant Ariadna Audouin, 1826 is described from Western Australia, based on morphological features of both the male and female, and elevating the total number of described species of Ariadna in Australia to 14. This is the first record of the tube-web spider family Segestriidae Simon, 1893 inhabiting salt lakes, where they construct burrows in to the lake surface. The species is likely to be of conservation importance, due to its specialised habitat requirements and the many threats posed to the salt lake ecosystem. We provide recommendation for Ariadna phantasma sp. nov. to be considered for inclusion in the IUCN Red List.

Argiope bruennichi (Scopoli, 1772) Örümceğinin Ağ Yapısı ve Örü Aygıtının Morfolojisi

Spiders are one of the groups that best adapted to terrestrial life among in invertebrates and are represented by approximately 48,000 species in the world. Although all spiders do not weave webs, the webs of spiders are literally a work of art. The main reason for spider web weaving is hunting. Some spider species live in the nature dependent on the own web, while others continue to live without being dependent on the own web. Although basic taxonomic features generally remain unchanged, some spider-silk weaving apparatus may undergo adaptive variations. In this study, the web structure of the weaving web spider, Argiope bruennichi (Scopoli, 1772) and the structural organization of the web weaving apparatus was observed by using scanning electron microscopy (SEM). The web structure of A. bruennichi, spinnerets especially posterior spinneret and arrangement of its spigots are shown and discussed in the light of the literature.

Potency Testing of Venoms and Antivenoms in Embryonated Eggs: An Ethical Alternative to Animal Testing

Venoms are complex mixtures of biologically active molecules that impact multiple physiological systems. Manufacture of antivenoms (AVs) therefore requires potency testing using in vivo models to ensure AV efficacy. As part of ongoing research to replace small animals as the standard model for AV potency testing, we developed an alternate in vivo method using the embryonated egg model (EEM). In this model, the survival of chicken embryos envenomated in ovo is determined prior to 50% gestation, when they are recognized as animals by animal welfare legislation. Embryos were found to be susceptible to a range of snake, spider, and marine venoms. This included funnel-web spider venom for which the only other vertebrate, non-primate animal model is newborn mice. Neutralization of venom with standard AV allowed correlation of AV potency results from the EEM to results from animal assays. Our findings indicate that the EEM provides an alternative, insensate in vivo model for the assessment of AV potency. The EEM may enable reduction or replacement of the use of small animals, as longer-term research that enables the elimination of animal use in potency testing continues.