Kolymopecten gen. nov. – a New Representative of Pectinoid Bivalves from the Lower–Middle Permian of the Boreal Superrealm

From the Lower-Middle Permian deposits of the Boreal Superrealm (Northeast Russia), a new genus of Permian pectinoid bivalves of the family Heteropectinidae – Kolymopecten gen. nov. with the type species K. kolymaensis (Maslennikow) is described. The genus also includes K. mutabilis (Licharew) and K. praekolymaensis sp. nov. All representatives of the new genus are quite simply constructed: their right weakly convex valve is ornamented with simple radial bifurcating ribs of two orders, and the left, much more convex valve is ornamented with intercalating ribs of up to five orders. The historical development of kolymopectens is briefly reviewed. Kolymopecten is one of the few “ancient” genera of Permian bivalves that survived the Late Kungurian regional faunal extinction, which affected all major benthic groups. Representatives of the genus are among the most widespread pectinoid bivalves in the Northeast of Russia, often forming mass accumulations, especially in the Artinskian-Kungurian deposits.