The genus Nosa introduced by Navás (1911) was redefined by Insom & Carfi (1989). Fifteen taxa were eventually assigned to the genus, although as a result of synonymies, the catalogue by Stange (2004) recognizes only two species: Nosa tigris (Dalman) and Nosa tristis (Hagen). A review of the type material, and a review of male genitalia, indicates that the taxon tristis Hagen and its two subspecies, tristis niansanus Kolbe and tristis brevifasciatus Stitz, do not belong to Nosa and should return to the group of species within African Palpares that have not yet been assigned to new genera. On the other hand, it is proposed to consider that the genus Nosa Navás consists of four valid species: Nosa leonina Navás, Nosa tigris (Dalman), Nosa hamata (Kolbe), and Nosa adspersa Navás. Synonymies are discussed. The geographical distribution of each species is given.