Skeletomuscular Modifications Associated with the Formation of an Additional Petiole on the Anterior Abdominal Segments in Aculeate Hymenoptera

The skeletomusculature of the anterior abdominal segments in Aculeata was examined to discuss the relationships among Formicidae, Vespidae (s.l.) and Scoliidae, and phylogeny among Formicidae. On the basis of ground plan for Aculeata hypothesized, the present study indicated 3 types of apomorphic states associated with the formation of an additional petiole. The abdominal characters showed that Vespidae is more closely related to Formicidae than to Scoliidae. The tiphiid-like abdominal appearance of Amblyoponini may be secondary modification for increasing the length of tergal muscles. A close relationship between the ponerine tribe Ectatommini and Myrmicinae was proposed in the present study, because among the aculeates these formicid groups alone had a lobe for attachment of tergal muscles developed on the pretergum of the third segment.