Wolga Skorikov, 1903

Luo, Yongting & Segers, Hendrik, 2013, On Pulchritia new genus, with a reappraisal of the genera of Trichotriidae (Rotifera, Monogononta), ZooKeys 342, pp. 1-12 : 8

Genus Wolga Skorikov, 1903

Type species.

Wolga spinifera (Western, 1894).

Emended diagnosis.

Tegument of head, and anterior part of trunk loricate, both head and foot entirely retractable. Anal segment relatively large, annulated; foot pseudosegments short, only the distal one sclerotized. Trunk lorica box-shaped, dorso-ventrally compressed, longer than wide, with relatively flat ventral and dorsal parts; facetted. No marginal spines or spinulets.

Discussion.

The published generic diagnosis refers to absence of an anal segment ( Koste 1978; Koste and Shiel 1989). This does not appear to be correct; the illustration of a non-contracted animal by Western (1894, reproduced by Koste (1978) and Koste and Shiel (1989)) depicts a foot consisting of a first element having numerous transverse folds indicating its high mobility, and two additional, relatively short pseudosegments; all but the terminal part may be indistinct in preserved specimens. We interpret the first element as being the anal segment. The foot is situated subterminally and can be retracted entirely into the lorica by which the anal segment becomes indiscernible; there are two separate toes. It is unlikely that the presence of short spines over the lateral antennae is diagnostic at the genus level.

Western (1894) notes that the lorica of the species would consist of plates connected with a membranous lateral invagination. While the lateral parts of the trunk lorica may be concave, they do not appear distinctly less sclerotized as in, e.g., many species of Lecane .