A New Species of Metacypris (Crustacea: Ostracoda: Cytheroidea: Limnocytheridae) from Hokkaido, Japan

Abstract

A new species of the freshwater ostracod genus Metacypris is reported from Kushiro Marsh, Hokkaido, Japan. Two large posterior brood chambers in the females give this species a perfect heart shape in dorsal view. The male is characterized by a digit-shaped plate on each hemipenis. This is the second living species of Metacypris to be described; the other species, M. cordata Brady and Robertson, 1870, is restricted to Europe. Furthermore, this new species of Metacypris is only the second endemic freshwater cytheroidean species so far reported from Japan and the first record of the family Limnocytheridae in Japan.