Brasergasilus bifurcatus sp Nov (Copepoda, Ergasilidae, Abergasilinae) from the gills and nasal fossae of serrasalmid fishes from the Tres Marias reservoir, upper Sao Francisco river, Minas Gerais State, Brazil

Brasergasilus bifurcatus sp. nov. (Copepoda, Ergasilidae, Abergasilinae) is described. Specimens of the new species were collected from the gills and nasal fossae of the serrasalmid fishes, known as "piranhas", Pygocentrus piraya (Cuvier, 1819) and "pirambebas", Serrasalmus brandtii (Lutken, 1875). The fishes were netted in the Tres Marias Reservoir (18 degrees 12'59 '' S, 45 degrees 17'34 '' W) of the upper Sao Francisco River, Minas Gerais State, Brazil. The new species differs from its congeners by the following characters: the specific setation on the antennule; the terminal barb of the antenna; the deeply bifurcate distal segment of the mandible; the chalice-shaped genital complex; a conspicuous external indentation of the second segment of the first endopod and a very short terminal segment of the first exopod.