Valvata (Cincinna) ambigua Westerlund 1873 (fig. 3, 5)

D i s t r i b u t i o n. The species inhabits rivers of Europe and south of Western Siberia (Anistratenko, Anistratenko, 2001; Vinarski et al., 2013). In Ukraine V. ambigua inhabits lotic waters in the middle and lower part of Dnipro basin (Anistratenko, Chernogorenko, 1989). A population of this species of low density was recently recorded also in the Latorytsia River basin, Transcarpathia (Stadnichenko, Gyrin, 2011 b). We found a few individuals of V. ambigua at a single locality (15) together with many others gastropod molluscs (fig. 1, table 1). Available data and our observations suggest this is apparently a regionally rare species.

Remarks. European authors mostly attribute this taxon to a synonymy of Valvata piscinalis (e. g. Welter-Schultes, 2012). Recently the problem was considered on the basis of studying the type material of Valvata ambigua (Vinarski et al., 2013) — its specific status is strongly argued because of the lower shell, the wider umbilicus of the type specimens. Shell morphology of snails collected in Transcarpathia (fig. 3, 5) corresponds well to the syntype of this species illustrated by Vinarski et al. (2013: fig. 1, A–C).