ИСТИНА

The genus Plumhoffia is recorded in the Middle Jurassic of Western Europe from the Early Bajocian. P. praequadricostae sp. nov. is recorded in southern Germany from the Sauzei Zone. In the Humphriesianum Zone the genus diverged, and P. praequadricostae, P. curvicosta Ohmert & Franz, P.? foveata sp. nov. and P. curticosta sp. nov. are distinguished. In this instance, evolution occured through phylogenesis, by the Late Bajocian and Bathonian speciation occurred by anagenesis. Based on this lineage: P. praequadricostae (Sauzei–Niortense zones) → P. brandi sp. nov. (Garantiana–Subcontractum zones) → P. quadricostae Brand (Morrisi–Hodsoni zones) new lineage zones are proposed for Western Europe. Representatives of P. brandi formed two geographical subspecies P. b. germanica ssp. nov. and P. b. polonica ssp. nov. These ostracods migrated to the Russian platform and populated new seas that established during the Bajocian transgression. In the Garantiana Zone, P. tricostata (Khabarova) colonized the Dnieper-Donetsk Depression, and in the Michalskii Zone entered the seas of European Russia and western Kazakhstan. The Russian platform Plumhoffia also diverged as P. tricostata ukrainica ssp. nov. and P. t. rossica ssp. nov., according to their first appearance the new eponymous migration units are proposed for Ukraine (Garantiana–Zigzag zones) and Russia (Michalskii–Besnosovi zones).