Evidence from study of the structure and extrinsic musculature of the midcoxae in Hymenoptera supports the following hypothesized relationships: Orussidae and Apocrita are sister-groups; no evidence was found supporting a sister-group relationship between Cephidae and Apocrita; the Ichneumonoidea (Stephanidae excluded), Chalcidoidea (including Mymaridae and Mymarommatidae), Proctotrupoidea (Ceraphronoidea excluded), and Cynipoidea form a monophyletic group, the Ichneumonomorpha; the Evanioidea, Ceraphronoidea, Megalyridae, and Trigonalidae form a monophyletic group, the Evaniomorpha.