Cryptachaea Archer, 1946

Smith, Helen M., Vink, Cor J., Fitzgerald, Brian M. & Sirvid, Phil J., 2012, Redescription and generic placement of the spider Cryptachaea gigantipes (Keyserling, 1890) (Araneae: Theridiidae) and notes on related synanthropic species in Australasia, Zootaxa 3507, pp. 38-56 : 44

Genus Cryptachaea Archer, 1946

Cryptachaea - Archer 1946: 36, established as a subgenus of Theridion Walckenaer, 1805 . Type species: Theridion catapetraeum Gertsch & Archer, 1942 [= C. porteri (Banks, 1896) ], by original designation. Elevated to genus by Archer 1950: 14. Considered a junior synonym of Achaearanea Strand, 1929 by Levi 1955: 6. Removed from synonymy of Achaearanea by Yoshida 2008: 38.

Diagnosis. Cryptachaea keys out under Achaearanea according to Levi & Levi (1962). Yoshida (2008: 38) distinguished Cryptachaea from the other genera with a hooded ‘paracymbium’ (cymbial hood of Agnarsson 2004) that key out under Achaearanea, Henziectypus Archer, 1946 and Parasteatoda Archer, 1946 , as follows: "... from Henziectypus by median apophysis attached to embolus with which it forms one sclerite, from Parasteatoda by cymbium extend [sic] beyond alveolus, tegulum spherical, and subtegulum shallow and ring-like".

Comments. Yoshida (2008) first transferred C. veruculata into the genus Cryptachaea , diagnosed partly by fusion of the median apophysis and embolus. In a superficial examination, these sclerites can be seen separately in both C. veruculata and C. gigantipes (Figs 14, 16). Further examination of these species shows that both sclerites are indeed fused onto a common base, but possibly retain some flexibility by the membranous sections (Fig. 15). The sclerotised part of the base of the median apophysis bears a prominent medial knob, which cradles the base of the embolus. Furthermore, there is a fleshy lobe with a sclerotised tip extending ventrally from the fused part of the median apophysis/embolus (shown as the latter in C. veruculata by Merrett & Rowe 1961: fig. 5). The lobe locates firmly in a proventral pocket in the conductor base. This pocket is visible externally as a dark outline in both species (e.g. Fig. 12). These features distinguish the two Australasian species from the cosmopolitan Cryptachaea blattea , in which the embolus and median apophysis are fused but neither the knob nor lobe/pocket is present ( C. blattea specimen examined: AM KS 116774, Stokes Valley, Wellington, NZ, coll. B.M. Fitzgerald, Oct. 2011).

We also note that the males of the three Cryptachaea species discussed here possess cephalothoracic stridulatory ridges and corresponding abdominal pegs. These characters are present in a number of theridiid genera ( Agnarsson 2004) but were not reported by Yoshida (2008) when he revalidated Cryptachaea .