The status of the Japanese Crocothemis servilia (Drury) as revealed by karyotypic morphology (Anisoptera: Libellulidae)

Close to JO populations pertaining to C. servilia s.I. from India, Nepal, Thailand. Singapore, continental China, the Philippines, Taiwan and Japan were examined cytologically. The type locality of the sp. is "China”, and its karyotypic morphology is uniform throughout continental Asia, the Philippines and Taiwan (2n<5 = 25, n$ = 13. m. XO). The Japanese material, which has been for a long time noticed for the "usually distinctly large size" of the individuals, is essentially distinct from all other populations, deviating from these in chromosome number (2n $ = 24, n$ = 12) and in mode of sex determination (neo-XY). Since these features are geographically limited to Japan, consistently expressed in all individuals examined, not subject to variation among individuals, do not show intrinsic genetic variability, and are not conditioned by the environment, the Japanese population is separated under the name C. servilia mariannae ssp. n. The type scries originates from Osaka, and all material examined is of Honshu provenience. This is the first case of erection of a new taxon in the Odonata on the basis of karyomorphological diagnostic characters.