Distinguishing between the East-Asiatic representatives of Paracercion Weekers & Dumont (Zygoptera: Coenagrionidae)

Eight species occurring in Japan and continental East Asia are separated by the morphology of their 6 terminalia and by the structure of the 5 pronotum and adjacent laminae mesostigmales. Paracercion barbatum is confirmed as a good species, probably restricted to China, where it co-occurs with P. impar and other spp. The continental East Asian P. v-nigrum is suggested to share a common ancestor with the Japanese P. sieboldii. On chorological grounds, the latter should not exist in Taiwan. Both sexes of all spp. are keyed.