Morphology of sternal glands in male polistine wasps (Hymenoptera: Vespidæ)

Abstract

The sternal glands of 28 species of male wasps belonging to 12 polistine genera are described. Glands and associated cuticular modifications of these males and of males described in past studies are compared to those of conspecific females. Males in species of four swarm-founding genera have glandular areas similar in morphology and location to those of females. The glands are comprised of ducted cells associated with either a bed of erect cuticular scales along the anterior edge of the fifth sternite (Metapolybia, Chartergus, andPolybia) or a band of hairs along the anterior margin of both the fifth and sixth sternites(Apoica). Ropalidia montana males have ducted gland cells on sternites five and six, rather than just on six as in congeneric females;Brachygastra augusti males have them on sternites five through seven, rather than just on five as in their conspecific females. Also unlike those of conspecific females, these glands are not associated with any cuticular modification. Species in the remaining three swarm-founding genera lack male sternal glands. Males of independent-founding genera (Mischocyttarus, Polistes, Belonogaster, andParapolybia) have glandular cells covering the posterior 2/3 or 1/2 of the sternite, rather than the anterior portion as in their congeneric females.