A review of the Ponto-Caspian genus Caspiohydrobia (Mollusca: Gastropoda: Hydrobiidae)

The paper reviews all available information on the species content, distribution and ecology of brackishwater hydrobiid snails belonging to the genus Caspiohydrobia Starobogatov, 1970. The annotated list of nominal species with remarks on their taxonomy, nomenclature and distribution is provided as well as photographic images of some type specimens and/or topotypes. In total, the genus includes 31 nominal species distributed almost exclusively within the former Paratethys basin. The lectotype for the species C. cylindrica Logvinenko et Starobogatov, 1969 is designated. A short overview of the known habitat preferences of various Caspiohydrobia species is provided. We consider Caspiohydrobia a genus of Ponto-Caspian origin, whose range extends southwards to Iraq, Iran and Tajikistan and northwards to West Siberia. The actual species content of the genus as well as its generic independence require a further integrative revision, since most of the nominal species of Caspiohydrobia are still known from dried shells only and may actually be synonyms of a few (or even a single) species.