A contribution to the glacial refugia hypothesis for Bythinella Moquin-Tandon, 1856: Bythinella schmidtii (Küster, 1852) and related species

Bythinella bavarica Clessin, 1877, B. austriaca (Frauenfeld, 1857) and B. schmidtii (Küster, 1852) live in springs of tributaries of the Donau. Tributaries with springs inhabited by B. austriaca flow into the Donau, roughly between the more upstream situated drainage area with B. bavarica and the more downstream situated drainage area with B. schmidtii. A Bythinella living within the distribution area of B. austriaca and as yet attributed to this species, however, is related, at least conchologically, to the two other species, i.e. B. schmidtii and B. bavarica. This finding might contribute to the glacial refugia hypothesis for Bythinella as discussed by Benke et al. (2007).