An Integrative Analysis of the Specific Distinctness of Valvata (Cincinna) ambigua Westerlund, 1873 and Valvata (Cincinna) piscinalis (Müller, 1774) (Gastropoda: Valvatidae)

Abstract

Valvata (Cincinna) piscinalis (Müller, 1774) is a widespread and variable Palaearctic freshwater snail species. Some authors have separated more depressed forms with a wider umbilicus as a distinct species, Valvata (Cincinna) ambigua Westerlund, 1873. The latter species was described from Scandinavia and has also been reported from Siberia and Kazakhstan and more recently from Central Europe. We conducted an integrative study of the delimitation and relationships of V. ambigua and V. piscinalis using both morphometric and molecular genetic analyses. Analyses of the morphometric data did not reveal differentiation into distinct clusters. Rather, the shell characteristics used to distinguish V. ambigua and V. piscinalis showed continuous variation. There is little variability in mitochondrial DNA sequences in the V. piscinalis complex. A median-joining network based on cytochrome oxidase sequences showed that the morphological character states supposedly characteristic of V. ambigua and V. piscinalis did not correlate with the genetic relationships of the individuals studied. We therefore consider V. ambigua to be synonymous with V. piscinalis.