THE SCIENTIFIC HERITAGE OF V. I. ZHADIN AND MODERN MALACOLOGY: IDENTIFICATION KEY FOR FRESHWATER PEARL MUSSELS (BIVALVIA: UNIONOIDA: MARGARITIFERIDAE) OF RUSSIA

Abstract

We provide an overview of the recent revisions of freshwater pearl mussels (Margaritiferidae) of European Russia, East Siberia and Russian Far East. Four species of pearl mussels inhabit the territory of Russia. There are the European pearl mussel (Margaritifera marga-ritifera) from rivers of the western part of the country, M. dahurica from the catchments of the Amur River, the Razdol'naya River and nearby small rivers, M. middendorffi from Kamchatka, Sakhalin Island, Kuril Islands, and M. laevis from Sakhalin Island and Kuril Islands. The reduced median phylogenetic network based on COI sequences shows that genetic distances between the four pearl mussel species of Russia correspond to the interspecific divergence level. At the same time, intraspecific genetic variability within each species is extremely low. In this paper we state that the current taxonomy of pearl mussels for Russia corresponds to the system suggested by V. I. Zhadin, who was years ahead of his time, considering that intensive studies in this direction have only started in the past decade. The resultant pearl mussel identification key based on conchological features almost agrees with the key from V. I. Zhadin's classical identification guide. We argue that the new identification guide for freshwater mollusks of Russia must be prepared with a profound revision of certain taxa. V. I. Zhadin's key could be used for identification of Unionoida during the transitional period, and further disambiguation of the taxonomic status, synonyms and generic affiliations of species should be done in accordance with the updated system of palearctic Unionoida.

Keywords

• pearl mussels
• systematics
• v. i. zhadin
• species identification guide
• review