The genus can be distinguished from other genera of Parnopini by the reduced palpi, the large metascutellar projection and the larger body size. Members of the genus are parasites of ground-nesting solitary wasps of the tribe Bembicini (Crabronidae: Bembicinae). A total of 16 species are recognised, most of which occur in the Palearctic and Nearctic Regions (with 4 and 7 species, respectively) (Kimsey and Bohart 1991). A few species are known from India and Africa. Only one species, P. grandior, is found in Europe (Rosa and Soon 2012). The genus has been divided into species-groups by Kimsey and Bohart (1991).