Eterosonycha Butler, 1932

Rix, Michael & Harvey, Mark, 2010, The spider family Micropholcommatidae (Arachnida: Araneae: Araneoidea): a relimitation and revision at the generic level, ZooKeys 36 (36), pp. 1-321 : 37-38

Genus Eterosonycha Butler, 1932

Eterosonycha Butler, 1932: 114 . Type species by monotypy Eterosonycha alpina Butler, 1932 . Roewer, 1942: 357. Bonnet, 1956: 1803. Transferred from Zodariidae to Textricellidae by Davies, 1985: 113. Platnick, 2009.

Textricella Hickman, 1945: 136 . Type species by original designation Textricella parva Hickman, 1945 . Forster, 1955: 200. Forster, 1959: 274. Forster, 1964: 95. Brignoli, 1983: 375, 695. Davies, 1985: 113. Platnick, 2009. syn. n. (but see also Davies, 1985: 113).

Affinities. The genus Eterosonycha appears to be the sister-lineage to Epigastrina from Tasmania ( Fig. 4 ).

Diagnosis. Species of Eterosonycha can be distinguished from all other Textricellini by the presence of a modified, enlarged tibia on the male pedipalp with pronounced posterior projections ( Figs 60 F–G). Eterosonycha is also one of only three textricellin genera (including Epigastrina , Guiniella ) with males that possess a dorsal scute on the abdomen ( Fig. 7E ), a large conductor on the pedipalp ( Figs 6 C–D) and a distal, prolateral tibial macroseta on leg I ( Figs 59 C–D). Species of Eterosonycha can be further distinguished from these similar taxa by the presence of a fleshy distal conductor with two divergent processes ( Figs 53A , 60C ).

Description. Very small, entelegyne Araneoidea : total length 0.80 to 1.20. Cephalothorax: Carapace without glandular depressions above maxillae; cuticle without glandular pits ( Fig. 56A ). Eight eyes present on anterior margin of pars cephalica ( Fig. 52C ); AME smallest. Chelicerae with bulging anterior projections in males; promargin with inner denticles, true teeth, a pair of fused setal sockets adjacent to base of fang and three peg teeth in males ( Fig. 57H ); ectal stridulatory ridges present in males ( Fig. 59A ).

Legs and female pedipalp: Legs three-clawed ( Fig. 58F ), covered with smooth or serrate hair-like setae; tibia I of males with distal, prolateral macroseta ( Figs 59 C–D). Trichobothria present on legs; tibiae each with three (legs I–III) or four (leg IV) trichobothria; metatarsi (legs I–III) each with single trichobothrium ( Fig. 58C ). Female pedipalp entire, five-segmented; claw absent ( Fig. 57E ).

Abdomen: Abdomen oval; anterior sclerite present around epigastric region and petiole; large dorsal scute present on males ( Fig. 54A ), absent on females ( Fig. 54B ); posterior sclerotic ring surrounding spinnerets weakly-sclerotised. Six spinnerets situated posterior to fleshy colulus (Fig. 71A); PMS of E. alpina with single medial AC gland spigot; PLS of E. alpina with complete triad, including enlarged, sinuous FL gland spigot. Anterior tracheal system with multiple anteriorly-directed tracheae (Fig. 51B); posterior tracheal spiracle absent.

Genitalia: Male pedipalp ( Fig. 60 ) relatively large; trochanter with modified prolateral seta forming stridulatory ‘tooth’; patella distally-expanded, with retrolaterallydirected, hooked ligulate retrolateral apophysis and ornate, ridged cuticular microstructure; tibia modified, enlarged, with one or more posterior processes; tegulum large, bulging posteriorly, with excavate evaginated tegular ridge and large, fleshy distal conductor with two divergent processes; embolus exposed, short (length <5× width) and spur-like. Female genitalia (Fig. 51) heavily sclerotised externally, with pair of separate, ‘twisted’ anterior spermathecae; insemination ducts heavily sclerotised, curving anteriorly; fertilisation ducts filiform.

Distribution. South-eastern Australia (Tasmania, Victoria and New South Wales), north to approximately Sydney (Fig. 217).

Composition. Two described species, Eterosonycha alpina Butler, 1932 , E. complexa ( Forster, 1959) and the two new species E. aquilina and E. ocellata . Two undescribed species, similar to E. aquilina and E. complexa , are known from Victoria.

Nomenclatural remarks. The genus Eterosonycha was originally described by Butler (1932) for the species E. alpina , from the Kosciusko National Park, New South Wales. The original description and illustrations of E. alpina were, unfortunately, woefully inadequate (Butler described three Micropholcommatidae in that paper, including two congeneric species of Micropholcomma , in two different families), and the true identity of this species was understandably missed by Hickman (1945) and subsequent authors. Thus, the family Textricellidae and the genus Textricella were described over a decade later by Hickman (1945) for T. parva (the type species) and two additional Tasmanian species, even though T. parva and E. alpina were conspecific taxa. Davies (1985) first recognised Eterosonycha as a textricellid similar to T. parva , suggesting then that the genus name Eterosonycha would have priority over the name Textricella . Eterosonycha alpina is hereby formally recognised as a senior synonym of T. parva , and Eterosonycha as a senior generic synonym of Textricella . However, the family-group name Textricellini is retained, as required under Article 40 of the International Code of Zoological Nomenclature ( International Commission on Zoological Nomenclature 1999).

Figures

Figure 4. Optimal cladogram for the Micropholcommatidae under equal and implied weights, and one of six equally parsimonious trees recovered from an equal weights analysis of the ‘new’ matrix (length = 135; see Appendix II). With the exception of the highlighted (*) node ‘Patelliella adusta + Micropholcommatini’, all clades shown were recovered in all iterations of an implied weights analysis (K=1–6); the phylogenetic position of P. adusta changed to ‘P. adusta + Textricellini’ under K-values 1–5. Unambiguous character optimisations are shown for each node, and bold species are newly described, with generic type species highlighted (*).

Figure 6. Scanning electron micrographs of ‘Inflaticrus’ sp. from the Langeberg Range, Western Cape province, South Africa (TM 15228): A male pedipalp, pro-ventral view B male bulb, pro-ventral view C detail of (B), showing basal conductor and embolus D tip of male pedipalpal patella, pro-ventral view E female sternum, ventro-lateral view, showing sternal pits F female posterior median and posterior lateral spinnerets, ventral view. Note the enlarged bCY gland spigot base on the PLS, the single cylindrical gland spigot on the PMS, and the absence of any posterior minor ampullate gland spigot or nubbin on the PMS (arrow denotes the anterior, mesal direction).

Figure 7. The genera of Micropholcommatidae, illustrated with habitus photographs of representative male specimens. A–D tribe Micropholcommatini: A Micropholcomma caeligenum Crosby & Bishop B Pua novaezealandiae Forster C Austropholcomma florentine sp. n. D Tricellina gertschi (Forster & Platnick). E–M tribe Textricellini: E Eterosonycha aquilina sp. n. F Epigastrina fulva (Hickman) G Raveniella peckorum sp. n. H Rayforstia vulgaris (Forster) I Normplatnicka lamingtonensis (Forster)] Eperiella alsophila sp. n. K Algidiella aucklandica (Forster) L Taliniella nigra (Forster) M Tinytrella pusilla (Forster). N Patelliella adusta sp. n., tribe Patelliellini. O–P subfamily Taphiassinae: O Olgania excavata Hickman P Taphiassa robertsi sp. n. Q–R subfamily Gigiellinae: Q Gigiella milledgei sp. n. R Gigiella platnicki sp. n. Note that Guiniella tropica (Forster) is not illustrated.

Figure 52. Eterosonycha aquilina sp. n. from Mount Donna Buang, Victoria. A, C holotype male (NMV K10766): A habitus, dorsal view C cephalothorax, antero-dorsal view. B, D allotype female (NMV K10767): B habitus, dorsal view D abdomen, ventral view.

Figure 53. Eterosonycha aquilina sp. n., paratype male from Mount Donna Buang, Victoria (WAM T94446): A left pedipalp, ventral view B left pedipalp, retrolateral view. Scale bar = 0.065 mm (65 µm).

Figure 54. Eterosonycha ocellata sp. n. from the Otway Ranges, Victoria. A, C holotype male (NMV K10768): A habitus, dorsal view C cephalothorax, antero-dorsal view. B, D allotype female (NMV K10769): B habitus, dorsal view D abdomen, ventral view.

Figure 56. Scanning electron micrographs of Eterosonycha alpina Butler from Mount Wellington, Tasmania (WAM T94105): A female carapace, lateral view B detail of (A), showing corner of carapace above left pedipalp C male cephalothorax, frontal view D male abdomen, antero-dorsal view E female sternum, ventro-lateral view F detail of (E), showing reticulate cuticle G male epigastric furrow, showing the absence of epiandrous gland spigots H female chelicera and labrum.

Figure 57. Scanning electron micrographs of Eterosonycha alpina Butler from Mount Wellington, Tasmania (WAM T94105): A female right chelicera (left removed), frontal view B female cheliceral promargin C detail of (B), showing prolateral fused setal sockets D detail of (B), showing cheliceral gland mound E female pedipalp, ventro-lateral view F female pedipalpal patella, showing distal bristle-like seta G male right chelicera (left removed), frontal view H male cheliceral promargin.

Figure 58. Scanning electron micrographs of female Eterosonycha alpina Butler from Mount Wellington, Tasmania (WAM T94105): A leg I tarsal organ B leg I lyriform organ C leg I metatarsal trichobothrium D leg I distal segments E leg I claws F leg IV claws, showing elongate inferior claw.

Figure 59. Scanning electron micrographs of male Eterosonycha alpina Butler from Mount Wellington, Tasmania (WAM T94105): A ectal cheliceral stridulatory file, ventral view B leg I distal segments, prodistal view C leg I distal segments, prolateral view D detail of (C), showing distal tibial macroseta.

Figure 60. Scanning electron micrographs of pedipalp of male Eterosonycha alpina Butler from Mount Wellington, Tasmania (WAM T94105).