The family-level classification and phylogeny of superfamily Zygaenoidea has been controversial for a long time. Currently it comprises 13 families: Heterogynidae, Zygaenidae, Lacturidae, Phaudidae, Anomoeotidae, Himantopteridae, Somabrachyidae, Epipyropidae, Cyclotornidae, Megalopygidae, Dalceridae, Aididae, and Limacodidae. The monophyly of this superfamily has never been tested using molecular phylogenetic methods. Although two morphological characters, e.g. the retractile head of the larva (at least in the later instars) and the second abdominal spiracle of the pupa, which is covered by the wings, are considered to support the monophyly, but their phylogenetic implications are still doubtful. In this presentation, the homology of male copulatory structures among the zygaenoid family groups is discussed in respect to morphology of the sclerites involved and musculature. We especially focus on the structures termed uncus, socius, gnathos, transtilla, and juxta. A peculiar functional and morphological replacement of male claspering apparatus by pregenital sternite and tergite possibly is likely one of the key innovations leading to higher diversity of several clades of Zygaenidae.