The new helconine genus Nipponocolpus Belokobylskij et Fujie, gen. nov. of the tribe Diospilini, with type species N. maetoi Belokobylskij et Fujie, sp. nov., from Japan (Honshu) is described and illustrated. The genus Baeacis Foerster, 1878 is restored from synonym with the genus Diospilus Haliday, 1933. Morphological characters used in Helconinae classification are discussed. A key for identification of the Holarctic genera of Diospilini is given.