Cypricercus inermis (Brady, 1904)

* 1904 Cypris inermis Brady: 125, pl. VIII. figs 44–49.

1910 Eucypris inermis —Daday: 167–169, pl. 9. figs 18–33.

1971 Tanycypris inermis —McKenzie: 172, 208.

2001 Cypricercus cuneatus —Martens: 62–64, 70.

2009b Cypricercus inermis — Savatenalinton & Martens: 2.

Diagnosis. L = 0.97–1.11 mm; H = 0.45–0.47; carapace in lateral view elongated. Length = 2.4 times height. Valves greyish-white. LV overlapping RV ventrally, LV longer than RV anteriorly, RV longer than LV posteriorly. Valve surface with shallow pits and thin setae. A1 with small Rome organ. T1 with a-, b- and d-seta.T2 with d1, which is twice as long as d2. CR stout with four groups of setulae on the ventral margin. CR attachment with Triebel loop in the middle, and a long, well developed vb (Brady 1904; Savatenalinton & Martens 2009b). Hemipenis with triangular lateral shield and rounded distal and medial shields. Zenker organ long with 22 chitinous rosettes (for more details see Savatenalinton & Martens 2009b).

History. Brady (1904) named this species Cypris inermis and provided its first description. Daday (1910) transferred the species to the genus Eucypris . McKenzie (1971) reported the existence of Tanycypris inermis, which he found in a “small clear pool, formed by drippings of a spring in the near of (sic) Rydal Mount, Witsieshoek, Orange Free State ”. Martens (2001) transferred it to Cypricercus under the assumption of synonymy with Cypricercus cuneatus, a view, that was not followed in Savatenalinton & Martens (2009b), where Cypricercus inermis and Cypricercus cuneatus were treated as two separate species, which “can be distinguished from it [ C. cuneatus] by the appearance of the unequal posterior valve margins, by the features of the caudal ramus and attachment and by the morphology of the hemipenis and the Zenker’s organ“ (Savatenalinton & Martens 2009b).

Conclusion. This species differs from Tanycypris in the presence of a well-developed vb and of a long groove in LV in C. inermis . The width of the carapace is greater than one-third of the length in C. inermis and thus greater than in the genus Tanycypris (Martens 2001; Savatenalinton & Martens 2009b).