Theridiidae Research Articles

Solid state 13C NMR and FT-IR spectroscopy of the cocoon silk of two common spiders

The structure of the silk from cocoons of two common spiders, Araneus diadematus (family Araneidae) and Achaearanea tepidariorum (family Theridiidae) was investigated by means of 13C solid state NMR and FT-IR spectroscopies. The combined use of these two techniques allowed us to highlight differences in the two samples. The cocoon silk of Achaearanea tepidariorum is essentially constituted by helical and β-sheet structures, whereas that of Araneus diadematus shows a more complex structure, containing also β-strands and β-turns. Moreover, the former silk is essentially crystalline while the latter contains more mobile domains. The structural differences of the two cocoon silks are ascribed to the different habitat of the two species.

Morphological phylogeny of cobweb spiders and their relatives (Araneae, Araneoidea, Theridiidae)

This paper offers the first cladistic analysis of a wide selection of theridiid genera based on morphological data. The analysis treats 53 theridiid taxa representing 32 genera (Achaearanea, Anelosimus, Ameridion, Argyrodes, Ariamnes, Carniella, Cerocida, Chrysso, Coleosoma, Dipoena, Emertonella, Enoplognatha, Episinus, Euryopis, Faiditus, Kochiura, Latrodectus, Neospintharus, Nesticodes, Pholcomma, Phoroncidia, Rhomphaea, Robertus, Selkirkiella, Spintharus, Steatoda, Stemmops, Theridion, Theridula, Thymoites, Thwaitesia, Tidarren) and eight outgroup taxa representing the families Nesticidae (Eidmanella and Nesticus), Synotaxidae (Synotaxus, two species), Pimoidae (Pimoa), Linyphiidae (Linyphia), Tetragnathidae (Tetragnatha) and Araneidae (Argiope). The parsimony analysis of 242 morphological and behavioural characters found a single, most parsimonious tree. The monophyly of theridiids and their sister relationship with nesticids is strongly supported. The recent resurrection of Ariamnes and Rhomphaea from Argyrodes made the latter paraphyletic. However, Ariamnes and Rhomphaea are characterized by an array of characters, and Argyrodes still contains dramatically distinct clades for which names are available: Faiditus (removed from synonymy − RS) and Neospintharus (RS). These revalidations provide a classification with greater information content and utility. These three genera, along with Ariamnes, Rhomphaea and Spheropistha, comprise the subfamily Argyrodinae. The monophyly and composition of the subfamilies Hadrotarsinae, Spintharinae, Pholcommatinae, Latrodectinae and Theridiinae are discussed. Theridion is paraphyletic and in need of revision. Anelosimus as currently circumscribed is paraphyletic, a problem resolved by revalidating Selkirkiella (RS) and Kochiura (RS). Numerous new combinations are established. The results suggest the monophyletic origin of both kleptoparasitism and araneophagy in the lineage leading to Argyrodinae, negating hypotheses that either arose from the other. Sociality evolved multiple times within the family, accounting for as much as one fourth of the origins of social behaviour among all spiders. No losses of sociality are implied. The hypothesis of maternal care as the pathway to sociality receives support. Evolution of theridiid webs is complex, with multiple modifications and loss of the basic theridiid cobweb. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 141, 447–626.

How to catch foliage‐dwelling spiders (Araneae) in maize fields and their margins: a comparison of two sampling methods

Abstract:The foliage‐dwelling spider fauna was collected in maize fields and on stinging nettles in adjacent margins in Bavaria, South Germany. Two different sampling methods were evaluated: drop cloth sampling and suction sampling. The overall catch was dominated by juvenile spiders, web‐building spiders, and spiders of the families Theridiidae, Linyphiidae, Tetragnathidae and Araneidae (in decreasing order). Field margins harboured more species than maize fields, whereas the total spider abundance was higher in the maize crop. Web‐building spiders such as Theridiidae and Linyphiidae were prominent in maize by individual numbers. Suction sampling with a small suction device proved to be a more efficient and consistent sampling method for foliage‐dwelling spiders than drop cloth sampling. Density and species richness of foliage‐dwelling spiders in maize was shown to be fairly high, implying that spiders of higher strata may play a more important role in biological control than suspected up to now.

Predation by cosmopolitan spiders upon the medically significant pest species Loxosceles reclusa (Araneae: Sicariidae): limited possibilities for biological control.

Interspecific predation of three cosmopolitan house spiders, Achearanea tepidariorum (Kock 1841) (Theridiidae), Steotoda triangulosa (Walckenaer 1802) (Theridiidae), and Pholcus phalangioides (Doleschall 1859) (Pholcidae), and the medically significant brown recluse spider, Loxosceles reclusa (Sicariidae) were examined to evaluate transitive predatory relationships and to explore the potential use of cosmopolitan spiders as effective biological control agents on L. reclusa. Fifty houses from northeastern Kansas were visually inspected from May to December 2002 for cosmopolitan spiders and L. reclusa. In 25 houses, insect monitoring traps were used to sample spider diversity and abundance. The remaining 25 houses were monitored to examine intraguild predation and spider behavior. If cosmopolitan spiders have the ability to regulate or decrease L. reclusa populations, houses with large cosmopolitan spider populations are expected to have significantly fewer L. reclusa than houses without cosmopolitan spiders. Predation and/or evidence of predation by all three cosmopolitan spiders on L. reclusa was detected in 68% of houses. Spearman's rank correlation analysis showed overall positive relationships between population densities of cosmopolitan spiders and L. reclusa. When evaluated independently, the presence of both A. tepidariorum and S. triangulosa showed negative, yet nonsignificant, relationships with L. reclusa densities, whereas P. phalangioides showed a positive nonsignificant relationship. Although statistical tests showed a decrease in L. reclusa population densities with increased population densities of two cosmopolitan species, alluding to a potential beneficial interaction for biological control, observations of spider behavior, web positioning (niche partitioning), and predation showed little possibility of biological control capabilities.

Additional records of Japanese species of the genus Robertus (Araneae: Theridiidae), with removal of a species as a junior synonym of Leptorhoptrum robustum (Linyphiidae)

Collecting data newly obtained of two Japanese species belonging to the family Theridiidae, Robertus nojimai Yoshida 2002 and R. ogatai Yoshida 1995, are presented. Robertus yasudai Yoshida 2001 is newly synonymized with Leptorhoptrum robustum (Westring 1851) belonging to Linyphiidae.

From a comb to a tree: phylogenetic relationships of the comb-footed spiders (Araneae, Theridiidae) inferred from nuclear and mitochondrial genes

The family Theridiidae is one of the most diverse assemblages of spiders, from both a morphological and ecological point of view. The family includes some of the very few cases of sociality reported in spiders, in addition to bizarre foraging behaviors such as kleptoparasitism and araneophagy, and highly diverse web architecture. Theridiids are one of the seven largest families in the Araneae, with about 2200 species described. However, this species diversity is currently grouped in half the number of genera described for other spider families of similar species richness. Recent cladistic analyses of morphological data have provided an undeniable advance in identifying the closest relatives of the theridiids as well as establishing the family’s monophyly. Nevertheless, the comb-footed spiders remain an assemblage of poorly defined genera, among which hypothesized relationships have yet to be examined thoroughly. Providing a robust cladistic structure for the Theridiidae is an essential step towards the clarification of the taxonomy of the group and the interpretation of the evolution of the diverse traits found in the family. Here we present results of a molecular phylogenetic analysis of a broad taxonomic sample of the family (40 taxa in 33 of the 79 currently recognized genera) and representatives of nine additional araneoid families, using approximately 2.5kb corresponding to fragments of three nuclear genes (Histone 3, 18SrDNA, and 28SrDNA) and two mitochondrial genes (16SrDNA and CoI). Several methods for incorporating indel information into the phylogenetic analysis are explored, and partition support for the different clades and sensitivity of the results to different assumptions of the analysis are examined as well. Our results marginally support theridiid monophyly, although the phylogenetic structure of the outgroup is unstable and largely contradicts current phylogenetic hypotheses based on morphological data. Several groups of theridiids receive strong support in most of the analyses: latrodectines, argyrodines, hadrotarsines, a revised version of spintharines and two clades including all theridiids without trace of a colulus and those without colular setae. However, the interrelationships of these clades are sensitive to data perturbations and changes in the analysis assumptions.

A new genus and three new species of the family Theridiidae (Arachnida: Araneae) from North Borneo

A new genus, Deelemanella, and three new species, D. borneo, Molione christae and M. kinabalu, belonging to the family Theridiidae are described from North Borneo.

Antivenoms for the Treatment of Spider Envenomation

There are several groups of medically important araneomorph and mygalomorph spiders responsible for serious systemic envenomation. These include spiders from the genus Latrodectus (family Theridiidae), Phoneutria (family Ctenidae) and the subfamily Atracinae (genera Atrax and Hadronyche). The venom of these spiders contains potent neurotoxins that cause excessive neurotransmitter release via vesicle exocytosis or modulation of voltage‐gated sodium channels. In addition, spiders of the genus Loxosceles (family Loxoscelidae) are responsible for significant local reactions resulting in necrotic cutaneous lesions. This results from sphingomyelinase D activity and possibly other compounds. A number of antivenoms are currently available to treat envenomation resulting from the bite of these spiders. Particularly efficacious antivenoms are available for Latrodectus and Atrax/Hadronyche species, with extensive cross‐reactivity within each genera. In the case of Latrodectus antivenoms this is of considerable impor...

Spiders of medical importance in the Asia-Pacific: atracotoxin, latrotoxin and related spider neurotoxins.

1. The spiders of medical importance in the Asia-Pacific region include widow (family Theridiidae) and Australian funnel-web spiders (subfamily Atracinae). In addition, cupboard (family Theridiidae) and Australian mouse spiders (family Actinopodidae) may contain neurotoxins responsible for serious systemic envenomation. Fortunately, there appears to be extensive cross-reactivity of species-specific widow spider antivenom within the family Theridiidae. Moreover, Sydney funnel-web antivenom has been shown to be effective in the treatment of mouse spider envenomation. 2. alpha-Latrotoxin (alpha-LTx) appears to be the main neurotoxin responsible for the envenomation syndrome known as "latrodectism" following bites from widow spiders. This 120 kDa protein binds to distinct receptors (latrophilin 1 and neurexins) to induce neurotransmitter vesicle exocytosis via both Ca2+-dependent and -independent mechanisms, resulting in vesicle depletion. This appears to involve disruption to a process that normally inhibits vesicle fusion in the absence of Ca2+. Precise elucidation of the mechanism of action of alpha-LTx will lead to a major advancement in our understanding of vesicle exocytosis. 3. delta-Atracotoxins (delta-ACTX) are responsible for the primate-specific envenomation syndrome seen following funnel-web spider envenomation. These peptides induce spontaneous repetitive firing and prolongation of action potentials in excitable cells. This results from a hyperpolarizing shift of the voltage-dependence of activation and a slowing of voltage-gated Na+ channel inactivation. This action is due to voltage-dependent binding to neurotoxin receptor site-3 on insect and mammalian voltage-gated Na+ channels in a manner similar, but not identical, to scorpion alpha-toxins and sea anemone toxins. delta-Atracotoxins provide us with highly specific tools to study Na+ channel structure and function 4. omega- and Janus-faced ACTX, from funnel-web spider venom, are novel neurotoxins that show selective toxicity to insects. In particular omega-ACTX define a new insecticide target due to a specific action to block insect voltage-gated Ca2+ channels. Both these ACTX show promise for the development of baculoviral recombinant biopesticides expressing these toxins for the control of insecticide-resistant agricultural pests. In addition, they should provide valuable tools for the pharmacological and structural characterization of insecticide targets.

A new species of the genus Takayus (Araneae: Theridiidae) from Nagano Prefecture, Central Japan

A new species of the family Theridiidae is described from Nagano Prefecture, Central Japan, under the name, Takayus fujisawai.

State-determinate foraging decisions and web architecture in the spider Dictyna volucripes (Araneae Dictynidae)

Foraging behaviors result from dynamic trade-offs made by organisms, incorporating factors such as past foraging success, reproductive effort, and predation risk. But, decision-making by animals occurs with incomplete information about the environment. We examined the relationship of web architecture and foraging decisions in the tangle web-building spider Dictyna volucripes Keyserling, a common spider in North American fields. Tangle webs are constructed over many days, which increases the total material and energetic investment in webs compared to orb-webs that are rebuilt daily. This reduces the profitability of changing web sites for tangle web spiders, making decisions about allocation of resources to foraging within single patches critical. We studied how foraging success affected investment in webs for High Prey spiders, fed two Drosophila daily, and Low Prey spiders, fed half that amount, over a 9-day period. We found no difference in the total area of silk added to webs. Increase in web area was proportional to initial web size in High Prey spiders, all of which increased webs by approximately 50%, despite substantial variation in initial sizes of webs. But, some Low Prey spiders with small initial webs increased web size by 200–300% while others, with large initial webs, invested proportionately little silk in webs. We also compared the effects of web architecture on prey capture of High and Low Prey spiders, under standardized prey density. There was no difference between High and Low Prey spiders in the number of Drosophila captured. We found a significant positive correlation between sizes of webs and prey capture in High Prey spiders but not in Low Prey spiders. We present the hypothesis that web investment by D. volucripes may incorporate information about both previous foraging effort and foraging success.

Two new species of the genera Chrysso and Achaearanea (Araneae: Theridiidae) from the Nansei Islands, Japan

Two new species of the family Theridiidae are described from the Nansei Islands, Japan, under the names, Chrysso sasakii and Achaearanea projectivulva.

Spiders active on snow in eastern Turkey

At temperatures below zero in winter months, a total of 202 spiders was collected by pitfall traps from a snow-covered grassland in eastern Turkey. 16 genera and 20 species were recorded, belonging to the families Gnaphosidae, Lycosidae, Linyphiidae, Thomisidae, Theridiidae, Philodromidae, Salticidae, and Tetragnathidae.

Contribution to the Knowledge of the Spider (Araneae, Arachnida) Fauna of Lithuania

The paper summarises information about 51 spider species new to the Lithuanian fauna from the families Pholcidae, Theridiidae, Araneidae, Lycosidae, Agelenidae, Hahniidae, Dictynidae, Liocranidae, Gnaphosidae, Philodromidae, Thomisidae, and Salticidae. 29 species belong to the species typical and common to Central Europe. The species Robertus ungulatus, Pirata insularis, Gnaphosa muscorum, nageles hilarulus, Attulus saltator, and Sitticus dzieduszyckii, have been recorded as rare in Europe. The occurrence of Haplodrassus dalmatensis, Cyclosa oculata, and Philaeus chrysops in Lithuania is interesting from the zoogeographical point of view. At present, the checklist of the Lithuanian fauna includes 328 spider species.

A New Species of the Genus Euryopis (Araneae: Theridiidae) from Japan

A new species of the spider family Theridiidae is described from Japan under the name, Euryopis nigra sp. nov.

The Spider Genus Achaearanea (Araneae: Theridiidae) from Japan

Twelve species of the genus Achaearanea belonging to the family Theridiidae are recorded from Japan. A key and illustrations of the species are given. A new species, A. ryukyu, is described. A. simulans (Thorell 1875) is recorded from Japan for the first time. A. ungilensis Kim & Kim 1996 described from Korea is synonymized with A. japonica (Bosenberg & Strand 1906).

Comparison of pome fruit orchard inhabiting spider assemblages at different geographical scales

Summary1 The composition of pome fruit orchard inhabiting spider assemblages was investigated at different geographical scales (Holarctic, European, inter‐ and intraregional levels within Hungary) using previous faunistic studies and data collected in Hungary between 1995 and 1997. Samples in Hungary were taken from the canopy and herb layer of apple and pear orchards in five markedly different fruit‐growing regions by beating and sweep‐netting methods.2 The composition of canopy spider assemblages of apple orchards was analysed for the Holartic region and found to be determined by latitude at family level, and by the main zoogoegraphical regions at genus level. At the European scale, both the genus and species composition changed along a north–south gradient.3 A comparison among apple and pear orchards located in different regions in Hungary, showed that both foliage‐ and grass‐dwelling spider assemblages varied considerably in species composition and dominance order.4 Within the same region, both the foliage‐ and grass‐dwelling spider assemblages showed moderate differences in apple and pear orchards submitted to different treatments. Although the assemblages of spiders inhabiting the canopy and the herbaceous layer can be unambiguously distinguished, some overlap still occurs.5 We conclude that the composition of spider assemblages is basically determined by geographical location. Although both pesticide treatments and available prey densities can influence the population of spiders, such factors are of moderate importance when compared with the effect of regionality, even when considered at smaller scale. However, most members of the family Theridiidae and the large orb‐weavers (Araneidae) decreased considerably in treated plots. Scale‐specific differences are thus relevant in determining the composition of prey–predator systems in orchards, and should be taken into account when designing integrated pest management (IPM) programs for apple and pear orchards.

Two Species of the Genus Theridion(Aranea: Theridiidae) from Japan.

A new species of the family Theridiidae is described from Japan, under the name Theridion nojimai sp. nov. Theridion ogasawarense Yoshida, 1993 is newly synonymized with T. melanostictum O. Pickard-Cambridge, 1876.

A New Species of the Genus Chrysso(Araneae: Theridiidae) from Japan.

A new species of the family Theridiidae is described from Japan under the name, Chrysso bimaculata.

Description of a New Species of the Genus Argyrodes (Araneae: Theridiidae) from Orchid Island, Taiwan, with Notes on its Ecology and Behavior.

A new species, Argyrodes lanyuensis of the family Theridiidae is described from Orchid Island, Taiwan. The ecology and behavior of the new species are reported.