The homology and terminology of the sclerotized structures, specifically the uncus and gnathos, formed by the fused segments caudal to the ninth abdominal segment in males of Lepidoptera, specifically in the Pyraloidea, have been confused in the literature. Based on comparative morphology of sclerotized structures and musculature, the uncus, scaphium, gnathos, and subscaphium are defined and described for stabilization in future systematic studies. Muscles IX-X (ex) and IX-X (int) are associated with these sclerotized structures and attached to the tegumen anteriorly. They are present in most of the species examined and are consistently topologically constrained in their origins and insertions; no differences were observed at the familial level. Muscle IX-X (int) is lacking in Pyralinae (Pyralidae) and this condition is hypothesized to be derived independently and an autapomorphy for this subfamily. The unique subteguminal processes of the Schoenobiinae are structures independent of the gnathos contrary to previous thought, and are instead associated with the valvae.
Published by Elsevier Ltd.