Meganeltumius Romero and Johnson and M. juani Romero and Johnson are described. This new genus and species are quite distinct due to the combination of the large gibbosities on the prothorax, the gibbosities on the elytra, the elongate genitalia, and especially the unique pattern of serrations on the metafemur. The hind femur is armed on its inner edge with about eight small serrations beginning about 0.5 from the base and ending at the apex in a subapical spine. This pattern of serrations and spines on the metafemur is unique to this genus of bruchids. All of these characters separate this species from any other and the pattern of serrations and spine on the metafemur separate this genus from any genus known to us. It resembles a large species of Neltumius Bridwell, consequently the name.