The type species of the genus Mesokalliapseudes Lang 1956, M. crassus (Menzies 1953), which was originally incompletely described and illustrated, is redescribed and a key to the species of the genus is provided. A study of type and non-type material indicates that M. crassus is a protandric hermaphrodite. All of the adult specimens of M. crassus examined, including presumptive males and preincubatory and incubatory females, had a male genital cone. In all other aspects, except for the development of oostegites in the female phase, this species expresses no marked sexual dimorphism.