Male polymorphism in some Old World species of Cryptocheilus Panzer (Hymenoptera: Pompilidae)

The hypothesis that males of certain species of the pompilid genus Cryptocheilus Panzer are polymorphic, first proposed by H. Wolf, is examined critically in the light of modern knowledge of the mating systems of Hymenoptera and the known biology of Cryptocheilus species. Speculations are made as to the likely selection pressures operating to produce this phenomenon; nine Old World species of Cryptocheilus are identified as probable examples. The taxonomic implications of the hypothesis are considered; one new generic and nine new specific synonymies are listed, and lectotypes are designated for three nominal species. Two names are retrieved from synonymy for species here recognized as valid. A key is provided for the extreme forms of the males of these species; more detailed treatment must await full revision of Cryptocheilus.