We present the description of two new subspecies of the Rhyacophila fasciata Group: Rhyacophila fasciata delici Kučinić Valladolid (ssp. nov.), broadly distributed in Croatia and present also in Bosnia and Herzegovina, and R. fasciata viteceki Valladolid Kučinić (ssp. nov.), found in Bosnia and Herzegovina. Our study of the morphology of adults, as well as our analysis of the barcode region of the mitochondrial cytochrome oxidase I (mtCOI) gene and geographical distribution confirm the differences of the two new subspecies with the nominal species R. f. fasciata, also found in both countries.
Keywords: Trichoptera, Taxonomic revision, new subspecies, identification, mitochondrial COI, distribution.