Review and redescription of species in the group of Smicridea (Rhyacophylax) (Trichoptera, Hydropsychidae, Smicrideinae): exploration of the utility of geometric morphometrics as a method for delimitation and characterization of species in the genus.

The species group includes five species distributed in northeastern Argentina and Brazil: Smicridea (Rhyacophylax) brasiliana (Ulmer), S. (R.) weidneri Flint, S. (R.) vermiculata Flint, S. (R.) arobasis Flint, and S. (R.) nanda Flint. The original descriptions of these species and their placement in the species group were mainly based on the morphology of the male genitalia. However, the fine structure of the internal sclerites of the phallus, which proved to be useful for species delimitation, was not analyzed at the time. In this contribution, we provide a detailed description of the male genitalia and the morphology of the head, and analyze the shape of the wings using geometric morphometrics. The analyzed species can be easily differentiated by the shape of the phallus, especially by the structure of the internal sclerites, the shape of the head in dorsal view, and the shape of the cephalic setose warts. Furthermore, the geometric morphometric approach allowed their separation through the wing shape. The preliminary analysis of these features suggests that the species group is not natural but its monophyly should be further tested within the framework of a phylogenetic analysis of all the species of the subgenus Rhyacophylax.