Theridiidae Research Articles

The protamines of the spider Steatoda sp. provide an example of liquid-liquid phase separation chromatin transitions during spermiogenesis.

While there is extensive information about sperm nuclear basic proteins (SNBP) in vertebrates, there is by comparison, very little information in Arthropoda. This paper aims to contribute to filling this gap by analyzing these proteins in the sperm of the noble false widow spider Steatoda nobilis (Order Araneae, Family Theridiidae). To this end, we have developed a protein extraction method that allows the extraction of both cysteine-containing and non-Cysteine-containing protamines that is suitable for the preparation and analysis of SNBPs from samples where the amount of starting tissue material is limited. We carried out top-down mass spectrometry sequencing and molecular phylogenetic analyses to characterize the protamines of S. nobilis and other spiders. We also used electron microscopy to analyse the chromatin organization of the Steatoda sperm and we found it to exhibit liquid-liquid phase spinodal decomposition during the late stages of spermiogenesis. These studies further our knowledge on the distribution of SNBPs within the animal kingdom and provide additional support for a proposed evolutionary origin of many protamines from a histone H1 (H5) replication independent precursor.

Changes in the material properties of spider glue droplet proteins accompanied shifts in prey capture biomechanics as cobweb spiders diverged from their orb weaving ancestors

Although descended from orb weavers, spiders in the family Theridiidae spin cobwebs whose sticky prey capture gumfoot lines extend from a silk tangle to a surface below. When a crawling insect contacts glue droplets at the bottom of a gumfoot line, the line's weak pyriform anchor releases, causing the taut line to contract, pulling the insect from the surface and making its struggles to escape ineffective. To determine if this change in prey capture biomechanics was accompanied by a change in the material properties of theridiid glue, we characterized the elastic modulus and toughness of the glue droplet proteins of four theridiid species at 20–90 % relative humidity and compared their properties with those of 13 orb weaving species in the families Tetragnathidae and Araneidae. Compared to orb weavers, theridiid glue proteins had low extensions per protein volume and low elastic modulus and toughness values. These differences are likely explained by the loss of tension on a gumfoot line when its anchor fails, which may prioritize glue droplet adhesion rather than extension. Similarities in theridiid glue droplet properties did not reflect these species’ evolutionary relationships. Instead, they appear associated with differences in web architecture. Two species that had stiffer gumfoot support lines and longer and more closely spaced gumfoot lines also had stiffer glue proteins. These lines may store more energy, and, when their anchors release, require stiffer glue to resist the more forceful upward thrust of a prey. Statement of significanceWhen a crawling insect contacts glue droplets on a theridiid cobweb's gumfoot line, this taut line's anchor fails and the insect is hoisted upward, rendering its struggles to escape ineffective. This strategy contrasts with that of orb weaving ancestors, which rely on more closely spaced prey capture threads to intercept and retain flying insects. A comparison of the elastic modulus and toughness of gumfoot and orb web glue proteins shows that this change in prey capture biomechanics is associated with reductions in the stiffness and toughness of cobweb glue. Unlike orb web capture threads, whose droplets extend in a coordinated fashion to sum adhesive forces, gumfoot lines become untethered, which prioritizes glue droplet adhesive contact over glue droplet extension.

A new monotypic genus of cobweb spiders from the Russian Far East (Araneae, Theridiidae).

A new theridiid spider, Knoflachiakurilensisgen. et sp. nov., is described from the Kuril Islands (Kunashir). The new genus belongs to the 'Anelosimus clade (clade 24)' of Agnarsson (2004). A pair of raised, fused setal sockets on the cheliceral promargin adjacent to the fang base was found to be another synapomorphy of all the 'distal theridiids' (the 'elongated central claw clade (clade 33)': argyrodins, 'Anelosimus clade' and theridiins). Knoflachiakurilensissp. nov. demonstrates a male polymorphism similar to some Anelosimus Simon, 1891 species (e.g., A.studiosus (Hentz, 1850)).

Deluded zombies: induced behavioral modification in a cobweb spider does not increase the survival of its parasitoid wasp

Deluded zombies: induced behavioral modification in a cobweb spider does not increase the survival of its parasitoid wasp

Non-targeted metabolomics aids in sex pheromone identification: a proof-of-concept study with the triangulate cobweb spider, Steatoda triangulosa

Targeted metabolomics has been widely used in pheromone research but may miss pheromone components in study organisms that produce pheromones in trace amount and/or lack bio-detectors (e.g., antennae) to readily locate them in complex samples. Here, we used non-targeted metabolomics—together with high-performance liquid chromatography–mass spectrometry (HPLC–MS), gas chromatography-MS, and behavioral bioassays—to unravel the sex pheromone of the triangulate cobweb spider, Steatoda triangulosa. A ternary blend of three contact pheromone components [N-4-methylvaleroyl-O-isobutyroyl-l-serine (5), N-3-methylbutyryl-O-isobutyroyl-l-serine (11), and N-3-methylbutyryl-O-butyroyl-l-serine (12)] elicited courtship by S. triangulosa males as effectively as female web extract. Hydrolysis of 5, 11 and 12 at the ester bond gave rise to two mate-attractant pheromone components [butyric acid (7) and isobutyric acid (8)] which attracted S. triangulosa males as effectively as female webs. Pheromone components 11 and 12 are reported in spiders for the first time, and were discovered only through the use of non-targeted metabolomics and GC–MS. All compounds resemble pheromone components previously identified in widow spiders. Our study provides impetus to apply non-targeted metabolomics for pheromone research in a wide range of animal taxa.

One less monotypic genus: a new species of the enigmatic Magnopholcomma (Araneae, Theridiidae) from Tasmania (Australia) with comments on its genital morphology and the generic placement in Pholcommatinae

A second species in the spider genus Magnopholcomma Wunderlich, 2008 (family Theridiidae Sundevall, 1833) is described based on a male found at Fortescue Bay in Tasman National Park (Tasmania, Australia). The genus differs from all other genera in the family by somatic characters, specifically the large globular clypeal outgrowth. Magnopholcomma adelphus sp. n. differs from M. globulus Wunderlich, 2008 by somatic and genitalic characters, especially the larger clypeal outgrowth, an inconspicuous fovea, pedipalp with longer tibia, median apophysis strongly basally projected and apical lobe of theridiid tegular apophysis undivided. The genus genital morphology and its systematic position in Pholcommatinae are also discussed, stabilizing the inconsistent nomenclature of sclerites of the male pedipalp (e.g., the interpretation of the theridiid terminal apophysis) of members of the subfamily.

Economic web-building behavior and behavioral investment trade-offs in a cobweb spider

Web-building spiders that build detritus-based bell-shaped cobwebs are model organisms for studies on behavioral plasticity because their web architecture components are easily quantified and behavioral investments are clearly separated. We investigated the web architectures and behavioral investments of the cobwebs built by Campanicola campanulata under different weight (heavy, medium, and light) detritus to research its cobweb architecture variation and analyzed the investment trade-off between foraging and defense. The results showed that spiders could actively choose lighter detritus to build retreats to reduce material and energy cost. There was a clear trade-off between defense and foraging investment of spiders choosing different weight detritus for their webs. The total length of gumfooted lines (foraging investment) was longer for the spiders that chose lighter detritus, but the energy expenditure during web-building (defense investment) was higher for the spiders that chose heavier detritus.

First record of the cobweb spider (Steatoda erigoniformis) from India

There are three species of the Genus Steatoda Sundevall, 1833 (Family Theridiidae Sundevall, 1833) distributed on the Indian subcontinent. Here, we report the first record of S. erigoniformis (O. Pickard-Cambridge, 1872) from India, specifically from Maharashtra and Rajasthan states. Previously, this species was known from Central Asia and China, but now its range extends south to Central India.

Invasive brown widow spiders avoid parasitism despite high densities.

Invasive species are sometimes less susceptible to natural enemies compared to native species, but the mechanism is often unclear. Here we tested two potential mechanisms for lower parasitism of invasive species: density-dependent parasitism and preference for human-dominated habitats. We investigated how variation in host density and habitat type affect egg sac parasitismintwo widow spider species (family Theridiidae). We compared parasitism on the egg sac of the brown widow,Latrodectus geometricus, an urban invasive species, and the white widow,Latrodectus pallidus, a species native to Israel. To investigate variation in host and parasitoid density, we measured nearest-neighbor distance between spider webs and parasitism rates in 16 sites, and in a single site monthly throughout a year. In L. pallidus, denser sites were more heavily parasitized (up to 55%) and parasitism rate increased with population density throughout the season. Extremely dense L. geometricus populations, however, had very low rates of parasitism (0-5%). We then conducted an egg sac transplant experiment in human-dominated and natural habitats. We found no parasitism of either species in the human-dominated habitat, compared to 30% parasitism of both species in the natural habitat. In addition, we found evidence for higher predation of L. pallidus than of L. geometricus egg sacs, particularly in the natural habitat. These combined results suggest that the human-dominated habitats inhabited by L. geometricus have a lower abundance of predators and parasites. We conclude that lower parasitism and predation in human-dominated habitats could contribute to the invasion success of L. geometricus.

They mostly come at night: Predation on sleeping insects by introduced candy-striped spiders in North America.

They mostly come at night: Predation on sleeping insects by introduced candy-striped spiders in North America.

Predation by the Introduced Brown Widow Spider (Araneae: Theridiidae) May Explain Local Extinctions of Native Black Widows in Urban Habitats

Abstract Invertebrates that successfully colonize new habitats often share life history characteristics including high fertility, rapid development, and early maturation. Since its introduction into Florida, USA, the non-native Brown Widow, Latrodectus geometricus (Kock 1841, Araneae: Theridiidae), has rapidly expanded its range into urban areas as far north as Kansas and as far west as California. During its expansion, the Brown Widow has displaced Florida’s Southern Black Widow, L. mactans (Fabricius 1775, Araneae: Tjerodoodae) and California’s Western Black Widow, L. Hesperus (Chamber lin & Ivie 1935, Araneae: Theridiidae). Here, based on a field survey and controlled laboratory experiments, we report possible causes for the rapid disappearance of Florida’s Southern Black Widows. Our field survey revealed that Brown Widows have twice the fertility potential as Southern Black Widows. In experiments comparing development, we show that sub-adult Brown Widows grew faster and matured earlier relative to Southern Black Widows. In our experiments on cohabitation with neighbors, bold Brown Widows were six times more likely to kill and consume shy Southern Black Widows than bold cobweb spiders and three times more likely to cohabitate with bold cobweb spiders than with shy Southern Black Widows. Our model of maternal risk-management revealed that competition for scarce prey was not a significant cause of offspring mortality for Latrodectus species. Hence, Brown Widows are not predating Black Widows or other cobweb spiders because prey is scarce. To our knowledge, this study is the first to suggest that aggressive predation by Brown Widows is a significant factor contributing to the local extinction of the shy Southern Black Widow in urban structures.

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New data on jumping spiders (Salticidae) and tangle-web spiders (Theridiidae) of Armenia are provided on the basis of recently collected specimens in various regions of Armenia. One species, Ballus rufipes (Simon, 1868) is recorded as new to the Caucasus Region, in addition to the following species: Neon reticulatus (Blackwall, 1853), Pellenes brevis (Simon, 1868), Salticus scenicus (Clerck, 1757) and Synageles dalmaticus (Keyserling, 1863) that belong to a family Salticidae, are recorded in Armenia for the first time. A further 7 species of Theridiidae are recorded in Armenia for the first time Kochiura aulica (C. L. Koch, 1838), Steatoda albomaculata (De Geer, 1778), Steatoda bipunctata (Linnaeus, 1758), Steatoda castanea Clerk, 1757, Steatoda grossa (C. L. Koch, 1838), Steatoda paykulliana Walckenaer, 1806 and Steatoda triangulosa (Walckenaer, 1802).

Safety is increasingly important in cobweb spiders based on life history.

Detritus-based, bell-shaped cobwebs are an ideal model to research the plasticity of web architecture due to clearly separate defense and foraging components. We performed a thorough field investigation on the web architectures of Campanicola campanulata to research its cobweb architecture variation during the growth process and analyzed the energy trade-offs between foraging and defense at different developmental stages. The results indicated that as female C. campanulata grew, they dedicated more energy to defense and less energy to foraging, while males dedicated less energy to both defense and foraging through the growth period. We hypothesize that cobweb spiders dedicate an increasing amount of energy to safety based on evidence obtained from their life-history. Meanwhile, we present a new model to investigate web architecture variation and provide a new framework to quantify the energy allocation between foraging and predator defense for web-building spiders.

Feeding mediated web-building plasticity in a cobweb spider.

Behavioral plasticity has been proposed as a means by which animals alter their phenotypes in response to changing conditions. Animals may display behavioral plasticity as a consequence of environmental variation. The detritus-based, bell-shaped cobweb spider Campanicola campanulata is an ideal model to study behavioral plasticity, because its web architecture is easy to be quantified, and the functions of different parts of the web are clear. Though the plasticity of cobweb architecture has been reported in a few species, retreats as important defensive structures have rarely been considered before because retreats in most cobwebs are relatively small compared with the web size. We studied the web-building behaviors of C. campanulata under different feeding regimes. We set up 3 spider treatments with different feeding conditions: marginally well fed, moderately well fed, and extremely well fed, and observed the differences in the web architecture among them. In addition, we measured the mechanical properties of anchor silk, and also calculated the foraging and defense investment of the spiders. The results showed that marginally well-fed spiders build cobwebs with significantly longer length of anchor silk, lower retreat to the ground, more number and longer gumfooted lines, and larger capture area, while extremely well-fed spiders build cobwebs with significantly bigger retreat volume and higher height of retreat to the ground. In addition, marginally well-fed spiders invest significantly less during cobweb construction. However, there was no significant difference between the breaking force and elongation at break in anchor silk among different treatments. These results demonstrated that marginally well-fed spiders invest more in foraging, and extremely well-fed spiders invest more in defense, and the spider made a balance between foraging and predator avoidance in response to changes in physiological state. Our study strengthens the current understanding of web construction in cobweb spiders, especially those facing high costs during retreat construction.

Feeding mediated web-building plasticity in a cobweb spider

Feeding mediated web-building plasticity in a cobweb spider

Meotipa species (Araneae, Theridiidae) from China.

In an ongoing effort to expand knowledge of the Chinese cobweb spider fauna (Theridiidae), the genus Meotipa Simon, 1894 is reviewed. Two new species are described, Meotipapseudopicturatasp. nov., Meotipastriatasp. nov., and five known species are redescribed: Meotipaargyrodiformis (Yaginuma, 1952), Meotipapulcherrima (Mello-Leitão, 1917), Meotipapicturata Simon, 1895, Meotipaspiniventris (O. Pickard-Cambridge, 1869), and Meotipavesiculosa Simon, 1895.

New data on the spider fauna of Iran (Arachnida: Araneae), part VII

New faunistic and taxonomic data are provided for 19 families of Iranian spiders. Stemonyphantes arta Esyunin et Zamani, sp. nov. (Linyphiidae) is described from a male and a female collected in the Zanjan Province. Five genera of the family Theridiidae (Pholcomma, Phoroncidia, Phycosoma, Rhomphaea and Rugathodes) and 21 species are recorded from Iran for the first time, and 119 new province records are provided for 51 species. Additionally, Megarctosa bamiana Roewer, 1960 (Lycosidae) is transferred to the genus Arctosa C.L. Koch, 1847. A mistake in the original description of Gnaphosa azerbaidzhanica Tuneva et Esyunin, 2003 (Gnaphosidae), namely a mismatch of the figures of this species with those of G. tigrina Simon, 1878, is discussed and corrected here. Considering the results presented in this paper, the total number of spiders recorded from Iran is raised to 888 species in 321 genera.

Eight cobweb spider species from China building detritus-based, bell-shaped retreats (Araneae, Theridiidae).

Eight cobweb spider species building a detritus-based, bell-shaped retreat from China are reported in the current paper, including five new Campanicola species and three known species: Campanicolaanguilliformis Li & Liu, sp. nov., Campanicolafalciformis Li & Liu, sp. nov., Campanicolaheteroidea Li & Liu, sp. nov., Campanicolatauricornis Li & Liu, sp. nov., Campanicolavolubilis Li & Liu, sp. nov., Campanicolacampanulata (Chen, 1993), Campanicolaferrumequina (Bösenberg & Strand, 1906), and Parasteatodaducta (Zhu, 1998). Among them, the male of Parasteatodaducta (Zhu, 1998) is described for the first time. We provide photographs of all species and descriptions for new species in the current paper. The type of bell-shaped retreat is rare in theridiid, and found only in four related genera. A natural next step upon completing this taxonomic study would be to analyse and understand the evolution of the retreat and related traits.

New records of Coleosoma blandum O. Pickard-Cambridge, 1882 and C. floridanum Banks, 1900 from Sri Lanka (Araneae: Theridiidae)

The comb-footed spiders Coleosoma blandum O. Pickard-Cambridge, 1882 (male only) and C. floridanumBanks, 1900 (male only) are redescribed, based on newly collected material from Sri Lanka. The latter species is reported for the first time from the island.

Faunal diversity of Theridiidae (Araneomorphae: Araneae: Arachnida) in India: An updated checklist

Faunal biodiversity of the comb-footed spiders (Theridiidae: Araneomorphae: Araneae: Arachnida) in different states of India and union territories is presented herewith. A total of 138 species placed under 42 genera of Theridiidae were recorded in all states and union territories of India except for Chhattisgarh, Jharkhand, Nagaland, and Punjab and two union territories, Dadra and Nagar Haveli and Daman and Diu, and Lakshadweep, out of which 45 species (32.6%) were strictly endemic. However, among them, 14 species seem to be case of erroneous report or misidentification. The maximum number of species (53 species) were recorded in Maharashtra followed by 51 from Kerala, 39 species from Gujarat, 33 species from Karnataka, 29 species from Tamil Nadu, 27 species from Jammu and Kashmir, 20 species from Uttarakhand, 17 species from West Bengal, 16 species from Assam, 15 species from Uttar Pradesh, 12 species each from Goa and Odisha, 11 species from Andaman and Nicobar Islands, 10 species each from Puducherry, Rajasthan and less than 10 species are recorded from other states. Four species are considerably widely distributed (in 10 or more states and union territories), viz. Chrysso angula (Tikader, 1970), Nesticodes rufipes (Lucas, 1846), Nihonhimea mundula (L. Koch, 1872), and Argyrodes argentatus O. Pickard-Cambridge, 1880. Several species of Theridiidae reported from India are recorded only from one state or from the type locality. Hence, extensive faunistic surveys for these spiders are required throughout the country.