Psychrodromus gen.n. (Crustacea, Ostracoda), with Redescription of the Cypridid Genera Prionocypris and llyodromus

The diagnoses of the genera Prionocypris and llyodromus are revised and two representative species, P. serrata and I. varrovillius , redescribed. Psychrodromus gen.n. is created for some species hitherto assigned either to Prionocypris or llyodromus. Detailed redescriptions of Ps. olivaceus (type species), Ps. robertsoni as well as information on Ps. fontinalis, Ps. turcicus and “Ilyodromus” estonicus are presented in order to establish the morphologic particularities of the new genus, which is Palearctic in its present distribution. Numerous morphologic structures, mostly hitherto ignored, proved to be useful in our systematic studies. The existence of several independent phylogenetic lines, in taxa once grouped loosely together, is established.