Two Pisidium species inhabit freshwater lakes of Novaya Zemlya Archipelago: the first molecular evidence

The information regarding freshwater mollusks of water bodies of Novaya Zemlya Archipelago is extremely limited. In 2015, the study of the lakes of the Southern Island of Novaya Zemlya Archipelago was undertaken within the framework of the research expedition of the “Arctic Floating University”. In general, two bivalve species were found in the lakes, Pisidium cf. conventus (Clessin, 1877) and P. waldeni (Kuiper, 1975). It is a northernmost record for Pisidium in the Palearctic Region. The present study provides the first occurrence of P. waldeni on the Novaya Zemlya Archipelago. The results of molecular analyses show that P. cf. conventus from Svyatoe Lake clusters together with the clade Odhneripisidium Kuiper, 1962. Our data are in accordance with the tabula rasa hypothesis, which states that the contemporary freshwater invertebrate fauna of the Novaya Zemlya originates through recent immigration processes after the Last Glacial Maximum.