Cyclocypris diebeli Absolon, 1973 (Ostracoda, Crustacea), extinct in Europe, extant in Japan.

Fossil Cyclocypris diebeli Absolon, 1973 from Europe are redescribed, utilizing material with chitinous preservation of the appendages and carapace. These are compared with living C. diebeli from Kushiro Marsh, Hokkaido, Japan, representing the first living population of this species ever found. The fossil material is associated with strongly calcareous sediments, whereas the living material is found in weakly calcareous to acidic waters. Reasons for the different ecological requirements are discussed. Detailed study of soft parts of both living and fossil material using SEM is compared with other Cyclocypris species and it is shown that C. diebeli is more closely related to the North American Cyclocypris cruciata Furtos, 1935 than to any European congeneric species. Furthermore, the comparison with other Cyclocypris species with left> right valve overlap results in the conclusion that the subgenus Laevicypris Krstić, 1995 is not a useful division of the genus. [ABSTRACT FROM AUTHOR]