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

A new genus of Permian pectinoid bivalves of the family Heteropectinidae, Kolymopecten gen. nov. with the type species K. kolymaensis (Maslennikow) is described from the Lower–Middle Permian deposits of the Boreal Superrealm (Northeast Russia). The genus also includes K. mutabilis (Licharew) and K. praekolymaensis sp. nov. All members of the new genus have quite simple morphology: their weakly convex right valve is ornamented with simple radial bifurcating ribs of two orders, while the left valve is much more convex and ornamented with intercalating ribs of up to five orders. The geological history of Kolymopecten is briefly reviewed. Kolymopecten is one of the few “ancient” genera of Permian bivalves that survived the Late Kungurian regional 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 beds.