SPINTHARINAE

Agnarsson, Ingi, 2004, Morphological phylogeny of cobweb spiders and their relatives (Araneae, Araneoidea, Theridiidae), Zoological Journal of the Linnean Society 141 (4), pp. 447-626 : 467-468

SPINTHARINAE : CLADE 45

Forster et al. (1990) discussed the possible composition of Spintharinae . They pointed out that a hooded ‘paracymbium’ ( Figs 75B , 92F–I, M ) was present in Spintharus and many other genera (explicitly including Anelosimus , Chrosiothes , Chrysso , Coleosoma , Helvibis , Nesticodes , Rugathodes , Spintharus , Tekellina , Theridula , Thwaitesia and Thymoites ). Yoshida (2001a) synonymized Spintharinae with Theridiinae , based on the same character, which he realized is also present in Theridion . The character of choice was unfortunate, as is evident from the present analysis.

First, Chrosiothes and Thwaitesia both, in fact, have a hook-lock system ( Fig. 92K , presumably overlooked by these authors), albeit with a groove present underneath the hook, whereas the remainder only have a hood. Second, both the current study and that of Arnedo et al. (2004) indicate that the hood found in Spintharus is not homologous to that found in the lost colulus clade (see Fig. 105); rather, it may be homologous to the groove lying underneath the hook of Thwaitesia and several related taxa. Here the subfamily Spintharinae is again used (following, e.g. Arnedo et al., 2004; contra Yoshida, 2001b).

The following genera included in this study belong in Spintharinae : Episinus , Spintharus and Thwaitesia . Based on similarity in morphology (e.g. abdominal shape and humps) and web type (H-shaped spintharine) it is likely that Chrosiothes and Moneta belong in this group. The remaining genera in Spintharinae sensu Forster et al. all belong to the lost colulus clade and have all been transferred to Theridiinae ( Yoshida, 2001b) . Molecular evidence suggests that Stemmops may belong to Spintharinae ( Arnedo et al., 2004) ; morphologically this arrangement may be supported by a spintharine cymbial hood that is found in some Stemmops (pers. observ.).

Unambiguous synapomorphies of Spintharinae include: conductor huge (63, Figs 46A–D , 83A–D , 90F, G ), conductor folded (66, Fig. 90F, G ), cheliceral base thin (118, Fig. 84C ), abdomen with humps (142), colulus small (173, Fig. 70A ), tarsal comb bristle dorsal margin notched (196, Fig. 84E ), and web modified (225, Fig. 97A ). Egg sac outermost fibre loosely spun (232, Fig. 88C ) is an ambiguous synapomorphy (ACCTRAN); there are no observations recorded for Spintharus .

Figures

Figure 46. Episinus maculipes, male. A–E, palp. A, mesial. B, ventral. C, ectal. D, close-up ventral. E, apical. F, prosoma with palp; the palp of Episinus, almost as large as the prosoma, is one of the relatively largest sperm transfer organs in the animal kingdom. G, prosoma dorsal view. Scale bars: 100 Mm.

Figure 70. Spintharus flavidus. A–C, spinnerets. A, B, female. A, all. B, left field. C, male PLS and PMS. D, tarsal comb, the notched dorsal margin (196-1) is a spintharine synapomorphy. E, chelicera prolateral margin. F, ditto, retrolateral margin, the peculiar outgrowth (arrow) was only seen in this species. Scale bars: A, D–F, 50 Mm. B, C, 20 Mm.

Figure 75. Theridion frondeum male. A–C, palp. A, ventral. B, mesial; note two lock mechanisms, embolus-tegulum lock mechanism, the apophysis on the E base (putatively homologous to the El in some other taxa, 98-1) fitting (50-1) in the tegular pit (lower arrow, 49-1), and the bulb-cymbium lock mechanism with a large cymbial hood (upper arrow, 33-1) where the distal arm of the MA fits (78-0). C, apical. D, prosomal stridulatory ridges. Scale bars: 100 Mm.

Figure 83. Thwaitesia male. A–F, Thwaitesia sp. A–E, palp. A, mesial. B, ventral. C, ectal. D, ventral close-up; note extra tegular apophysis (ETA, 101-1). E, the extremely elongated tibia is a putative synapomorphy of Thwaitesia. F, epiandrous gland spigots. G, T. margaritifera, epiandrous gland spigots. Scale bars: A–C, E, 100 Mm. D, F, G, 20 Mm.

Figure 84. Thwaitesia. A–C, Thwaitesia sp. A, female left spinning field. B, female PLS; note absence of FL (arrow, 212-1). C, male prosoma. D–F, T. margaritifera female. D, cheliceral fang and the characteristically sharp (107-1) teeth. E, tarsal comb. F, tarsus I, the modified ventral setae (arrows) are similar to those present in hadrotarsines, but unlike in hadrotarsines, are not tightly grouped (197-0). Scale bars: A, 50 Mm; B, D, 20 Mm; C, E, F, 100 Mm.

Figure 88. SEM images of theridiid egg sacs. A, B, Latrodectus geometricus. A, sac with fairly densely woven fibres (232-0). B, details of individual fibres (233-0). C, D, Thwaitesia sp. C, loosely woven sac, the outermost fibres extremely loose (232-1). D, details of an extremely spiny fibre (233-1), perhaps a protection against predators/parasites. The phylogenetic distribution of spiny eggsac fibres is unknown. E, F, Argyrodes sp. E, densely woven sac with smooth fibres (233-0) and a distinct stalk (230-1). F, details of stalk, a synapomorphy of Argyrodinae. G, H, Theridion sp. G, dense egg sac. H, details of fibres. Scale bars: A, C, E, G, 100 Mm; F, 50 Mm; B, D, H, 10 Mm.

Figure 90. Theridiid palps. A, Anelosimus sp. nov. (Tanzania). B, ditto, sperm duct trajectory. C, Anelosimus vittatus. D, ditto, sperm duct trajectory. E, indicating loops of A. vittatus sperm duct trajectory. F, G, Episinus angulatus (Blackwall) (redrawn from Knoflach, 1993). H, Carniella schwendingeri Knoflach (redrawn from Knoflach, 1996). Trichobothria omitted in F–H.

Figure 92. Schematic illustrations of palpal cymbia. A, Argiope argentata. B, Tetragnatha extensa. C, Nesticus reclusus. D, Steatoda americana. E, Argyrodes argyrodes. F, Anelosimus studiosus. G, Thymoites sp. H, Anelosimus vittatus. I, Ameridion nr. petrum. J, Euryopis sp. K, Thwaitesia sp. L, Selkirkiella alboguttata. M, Spintharus flavidus. Note that trichobothria are omitted in G, H and M.

Figure 97. A, Episinus sp. in web (225-4), posterior line held with one leg IV; leg pairs I, II both holding on to the line in front of the animal (Perinét, Madagascar). B–D, Phoroncidia spp., simple line webs (225-6). B, typical posture of a single line web, the spider holding on to dry silk near substrate; note transition to sticky silk (Ranamofana, Madagascar). C, similar position to Episinus, but uses only single leg I to hold line in front of the animal (Puyehue, Chile). D, closer. E, Thwaitesia sp. habitus (Sodwana Bay, S. Africa). F, Tidarren sp. (Fanies Island, S. Africa); note characteristic thin white band on abdomen. G, ditto, web.