Ostracods of the Gryazno Formation (Upper Ordovician, Sandbian Stage and Idavere Regional Stage) in the West of Leningrad Region

A brief description of two sections of the Gryazno Formation (Upper Ordovician, Sandbian Stage and Idavere Regional Stage (CIII)) in a typical locality in the west of the Leningrad Region (Klyasino and Zhabino), including a study of the taxonomic composition of ostracods (48 species), is given. One new genus with the type species Klyasinella bella and two new species of ostracods, Deefgella? pulchra and Longiscula? destorta, are described. Analysis of the stratigraphic distribution of ostracods of the Gryazno assemblage shows the similarity of many of its species with species from coeval Late Ordovician deposits in other areas of the Baltic region. In addition, single species of this assemblage are known from the deposits of the Polomet Horizon of the Moscow Syneclise