Acanoides, Sun, Ning, Marusik, Yuri M. & Tu, Lihong, 2014

Sun, Ning, Marusik, Yuri M. & Tu, Lihong, 2014, Acanoides gen. n., a new spider genus from China with a note on the taxonomic status of Acanthoneta Eskov & Marusik, 1992 (Araneae, Linyphiidae, Micronetinae), ZooKeys 375, pp. 75-99 : 80-82

Acanoides gen. n.

Type species.

Acanoides beijingensis sp. n.

Composition.

Two species, Acanoides beijingensis sp. n. and Acanoides hengshanensis (Chen & Yin, 2000) comb. n.

Diagnosis.

The males of Acanoides gen. n. can be distinct from Acanthoneta by the sharp embolus proper, the slender lamella characteristica unbranched, and by the Fickert’s gland located in the membranous area outside the radix (Figs 2D, 3D). The females can be distinguished by the ventrally folded extensible epigynal basal part (Figs 2F, 3F).

Description.

Male total length 2.34-2.73; female total length 2.10-2.42. Carapace yellowish-brown. Male carapace unmodified. AMEs smallest, others subequal; from the dorsal view AER recurved, PER straight, eyes separated by AMEd, ALE and PLE juxtaposed. Chelicerae medium-sized, with strong stridulatory ridges, female fang groove with three promarginal and three retromarginal teeth in Acanoides beijingensis sp. n., and two promarginal and two retromarginal teeth in Acanoides hengshanensis . Chaetotaxy: Ti I–IV: 2-2-2-2; Mt I–IV: 1-1-1-1; Mt I of males with two rows of ventral bristles, one prolateral, one retrolateral (Fig. 1C, 1D); Tm I about 0.25, Tm IV absent. Both species have a haplotracheate system.

Male palp (Figs 2 A–E, 3 A–E, 4 A–B, 5 A–B). Cymbium with proximal apophysis. Paracymbium medium to large-sized, with one tooth on lateral margin. Distal suprategular apophysis not modified as pit hook, or absent. Embolic division: radix long and narrow, Fickert’s gland located in the membranous area connecting radix and embolus; embolus wide and strongly sclerotized with serrated area, embolus proper sharp with a thumb and an apex at each side; lamella characteristica unbranched, long and narrow with sharp sclerotized apex, almost parallel to radix; terminal apophysis with distal membrane.

Epigynum (Figs 2 F–H, 3 F–G, 4 G–H, 5 G–H). Protruding, with deeply wrinkled basal part, extensible and ventrally folded in constricted state. Epigynum well sclerotized, epigynal cavity present (in Acanoides beijingensis sp. n.) or absent (in Acanoides hengshanensis ), both scape and stretcher absent.

Etymology.

The genus name, Acanoides , is a combination of the first four letters of " Acanthoneta " and the last five letters of “Wubanoides”. “-oides” itself in Latin means "similar to", masculine in gender.

Phylogenetics.

Due to limitations of the current dataset the monophyly of Acanoides could not be tested explicitly in our phylogenetic analyses, however it is supported by the following four putative synapomorphies: sharp embolus proper, slender and unbranched lamella characteristica, outside radix located Fickert’s gland and ventrally folded extensible epigynal basal part.

Distribution.

China (Beijing, Hunan, Hebei) (Fig. 7).

Remarks.

The males of Acanoides gen. n. have the palp of a “micronetine” type: presence of the Fickert’s gland, the boat-shaped radix, the trunk-like embolus with a pointed proper and a thumb, as well as the well developed terminal apophysis and lamella characteristica ( Saaristo and Tanasevitch 1996). However, these sclerites in Acanoides (Fig. 2D) have some features different from the normal “micronetine” type (Fig. 6F, Saaristo and Tanasevitch 1996): Fickert’s gland is not embedded within the radix, but located in the membranous area connecting the radix and the embolus; and the embolus has a wide, strongly sclerotized body, with a longer and sharper embolus proper, whereas in most “micronetines” the embolus is usually trunk-like with a pointed embolus proper. The male palp of both Acanoides and Acanthoneta , have a long and slender lamella characteristica parallel to the long radix, but with an additional long and thin branch in Acanthoneta (Fig. 6F), unbranched in Acanoides (Figs 2D, 3D). The epigynum of Acanthoneta is in a normal “micronetine” type, with a sigmoid scape surrounded by an epigynal cavity (Fig. 6H), but with an extensible basal part in Acanoides .

The result of phylogenetic analysis based on molecular data indicates that Ipainae is not a monophyletic group as the movable epigynum independently evolved in Acanoides and Solenysa (Appendix - Fig. S1). This is also supported by the tracheal characters: haplotracheate type in Acanoides , but intermediate type in Solenysa , with the median pair extending into the prosoma ( Tu and Hormiga 2011). We infer that the extensible basal part of the epigynum may have also evolved convergently with that in other ipaines. In Acanoides it differs by being ventrally folded, while it forms a solenoid in Solenysa (Tu & Hormiga, 2011), and folds inwards in other ipaines, e.g. Ipa ( Saaristo 2007: fig. 29), Wubanoides and Epibellowia ( Tanasevitch 1996: figs 7-9). Furthermore, the male palp of typical ipaines has filiform embolus proper ( Saaristo 2007: fig. 7; Tanasevitch 1996: figs 1, 4) much longer than that of Acanoides (Fig. 2D).