The genus Sinonereis Wu & Sun, 1979 and the species Sinonereis heteropoda Wu & Sun, 1979 were described from Chinese waters, based on only epitokous specimens with modified dorsal cirri in chaetigers 5-7 and bare pharynx. In the same publication, another species based on only atokes was described, Nicon sinica Wu & Sun, 1979. We show that N. sinica is a junior synonym of S. heteropoda based on their affinities in chaetal and parapodial features. We redefine Sinonereis and formally synonymize N. sinica and S. heteropoda. Sinonereis closely resembles Nicon Kinberg, 1865 and Kainonereis Chamberlin, 1919, but Sinonereis differs from them by having napiform dorsal cirri in chaetigers 5-7, and by lacking notopodial dorsal ligules in chaetiger 3 in both atokes and epitokes.
Nereididae, modified dorsal cirri, epitoky, sexual dimorphism, polychaetes, new synonym.