Diversibranchius nicolaji gen. et sp. n. is described from the Bay of Peter the Great (Sea of Japan). The species is characterized by simple capillary setae in both rami of parapodia and by 4 pairs of branchia of two types, leaflike and cirrifprm, both with folds of complex structure. Further, each of leaflike gills has two hillocks on the upper surface. Such branchial structure is described for the first time. The species is close to Diplocirrus Haase and D. cf. capensis in particular (Spies, 1975). The latter apparently belongs to a new genus
