The Neotropical genus Melanocryptus Cameron is revised, with a new defense for the genus based on an entirely new redescription. The genus is characterized mainly by the following characters: apical half of female flagellum with a ventral stripe formed by dense, short pilosity; clypeus with a central pointy tooth; areolet large, pentagonal, about as long as wide, sides converging anteriorly; and ovipositor blade shaped, about 2.0–3.0× higher than wide. Eleven valid species are recognized: M. cyaneus (Schmiedeknecht), M. niger (Szépligeti), M. violaceipennis Cameron, M. whartoni Kasparyan et Ruíz, and seven new taxa, M. aurantius, sp. nov., M. delos Aguiar, sp. nov., M. dnopheros, sp. nov., M. hadroglyptus Aguiar, sp. nov., M. rufigladius, sp. nov., M. tesselatus Aguiar, sp. nov., and M. tupan, sp. nov. The complex morphological variation of male specimens, particularly for M. hadroglyptus, was cladistically investigated in order to objectively delimit and demonstrate the range of morphological variation of the involved species. The first host record is reported for the genus, an unidentified pyralid moth (Lepidoptera), attacked by M. whartoni. The males of M. cyaneus and M. niger are reported for the first time. Photographic illustrations and distribution maps are provided for all valid species, with several new distribution records for previously known taxa. Keys for the species are presented separately for females and males.