Taxonomic Importance of the Female Apicoventral Setae on Hindtarsomere V of the Pompilidae (Hymenoptera), with Special Reference to Phylogeny of the Family

The apicoventral setae on hindtarsomere V of the Pompilidae were investigated with stereomicroscopy and SEM. Character states of the setae were roughly divided into two categories : long and setiform (state 0, plesiomorphic) and broad, flattened, bladelike (state 1, apomorphic). The ultrastructure of several types of apicoventral setae was described and illustrated. In females, state 0 was found only in Irenangelus and Ceropales (Ceropalinae), with the exception of Ceropales pacifica and C. rugata. State 1 was observed in all other groups of Pompilidae examined. Based on state 1 setae, all subfamilies except Ceropalinae were associated into a monophyletic group. The Ceropalinae was treated as the functional outgroup within the Pompilidae. Most of the characteristics of Ceropalinae were regarded as plesiomorphic, except for three features which were discussed in relation to a cleptoparasitic mode of life.