Ultrastructural characteristics of the spermatozoa of Scelionidae (Hymenoptera, Platygastroidea) with phylogenetic considerations

Abstract

The Scelionidae sperm are distinguished from those of all hymenopterans already studied at least by the presence of a single mitochondrial derivative and the absence of a centriolar adjunct. The absence of an acrosome, in Telenomus podisi, is also unique. The helical nucleus and mitochondrial derivative spiralling around a twisted axoneme can be considered as synapomorphies shared with the Chalcidoidea, and the mitochondrial derivative running together with the nucleus for a long distance can be considered as a synapomorphy shared with the Diapriidae. Therefore, from a consideration of these features, it is possible to suppose that the Scelionidae, Chalcidoidea and Diapriidae are more closely related between themselves than are any of them to the Cynipoidea, since the latter does not share any of the above‐mentioned features. This supposition agrees with phylogenetic analyses that supported the inclusion of Platygastroidea (Scelionidae and Platygastridae) and Chalcidoidea within the Proctotrupomorpha lineage, as well as the close relationship of these to the Diapriidae, and the exclusion of the Cynipoidea from this lineage.