Freshwater molluscs of the Olenek River basin (Eastern Siberia): morphological, molecular and taxonomic assessment with redescriptions of two species

This study presents the first assessment of the species composition and genetic diversity of freshwater molluscs of the Olenek River basin located in the northwest of Republic of Sakha (Yakutia) (Northeastern Siberia). Based on new field sampling, 20 species of freshwater molluscs, belonging to 12 genera and four families, were recorded.

We provide re-descriptions of <i>Pisidium dilatatum</i> Westerlund, <a target="_blank" href="#CIT0076">1897</a>, and <i>Valvata confusa</i> Westerlund, <a target="_blank" href="#CIT0076">1897</a>, based on samples collected from their type localities. On the basis of integrative evidence, the species status of <i>Sibirenauta sibirica</i> (Westerlund, 1877) is confirmed. The genetic similarity of snails of several species (<i>Valvata confusa</i>, <i>Sibirenauta sibirica</i>, <i>Radix auricularia</i>, <i>Ampullaceana lagotis, Lymnaea sorensis</i>, and <i>Kamtschaticana kamtschatica</i>) from the Olenek River basin with their conspecifics in other regions of Northeastern Asia is demonstrated, and the probable route of their dispersal to the Olenek River basin is discussed.