Determining Sexual Dimorphism of Living Aquatic Beetles, Stygoparnus comalensis (Coleoptera: Dryopidae) and Heterelmis comalensis (Coleoptera: Elmidae), Using Internal Abdominal Structures

The Comal Springs dryopid beetle, Stygoparnus comalensis Barr and Spangler, and the Comal Springs riffle beetle, Heterelmis comalensis Bosse, Tuff, and Brown, are protected by the United States Fish and Wildlife Service (USFWS), and the development of a captive self-propagating refuge is of importance to stakeholders within the Edwards Aquifer. Being able to reliably distinguish the sex of living subjects is desirable for establishing a...