First description of male genital sclerites and associated musculature for two members of Coniopterygidae (Insecta: Neuropterida: Neuroptera) based on X-ray microCT imaging

Abstract

Coniopterygidae are the dwarfs among the Neuroptera. Despite their miniaturisation, the males are equipped with genital sclerites that are excessively heterogeneous. They function in copulation and sperm transfer and have been widely utilized for species identification, as well being considered of high phylogenetic relevance. The present study is the first to describe the musculature associated with the genital sclerites of two species of Coniopterygidae, Helicoconis lutea (Wallengren, 1871) (Aleuropteryginae), and Coniopteryx pygmaea (Enderlein, 1906) (Coniopteryginae) based on X-ray microCT imaging. We found six pairs of muscles associated with the genital sclerites in H. lutea and seven in C. pygmaea. The images depict other internal organs of the posterior abdominal segments, such as gonads and alimentary canal. In both investigated species, the internal sclerites support the ductus ejaculatorius, which – surprisingly – turned out to be a landmark for the identification of closely adjacent internal sclerites and associated musculature. The interpretation of these sclerites as gonocoxites and gonapophyses of the tenth segment (traditionally denoted as parameres and penis) could be corroborated. Thus it is no longer tenable to assert that possession of a “penis” is exclusive to Coniopterygidae, since this sclerite is part of the ground pattern in Neuroptera. Interactions of genital sclerites and corresponding musculature during copulation are discussed.