The relationship between the genera Colasia Koch, 1965 and Belousovia Medvedev, 2007 within the tribe Blaptini is discussed, and a new synonymy is proposed: Belousovia Medvedev, 2007, syn. nov. of Colasia Koch, 1965. As a result, three new combinations are established: Colasia helenae (Medvedev, 2007), comb. nov., C. kabaki intermedia (Medvedev, 2007), comb. nov., and C. kabaki kabaki (Medvedev, 2007), comb. nov.Colasia akisoides Koch, 1965 is redescribed, and a lectotype is designated. Three new species of the genus Colasia are described and illustrated from China: C. bijicasp. nov. (Guizhou), C. medvedevisp. nov. (Yunnan), and C. pilosasp. nov. (Yunnan). A distribution map and a key to species of the revised genus Colasia are presented.