A Revision of the Genus Cincticostella (Insecta : Ephemeroptera : Ephemerellidae) from Japan

The Japanese mayfly genus Cincticostella is taxonomically revised. The four currently recognized species are Cincticostella (Cincticostella) elongatula (McLachlan, 1875) (=okumai Gose, 1980, syn. nov.), C. (C.) levanidovae (Tshernova, 1952), C. (C.) nigra (Ueno, 1928), and C. (C.) orientalis (Tshernova, 1952) (=tshernovae (Bajkova, 1962). The lectotype and paralectotypes of Ephemerella nigra are designated from the syntypes of Ueno. Specimens treated as C. (C.) nigra by many authors are identified with C. (C.) elongatula. All species are redescribed based on examined types and newly collected specimens. Keys are given to all stages : imagoes, subimagoes, nymphs, and eggs. Illustrations, complete synonymies, and distributional records are included for all the species, and the life histories of two species, C. (C.) elongatula and C. (C.) nigra, are presented.