The Rhyacophila fasciata Species Complex (Trichoptera: Rhyacophilidae) in Central Europe with description of a new species, Rhyacophila loeffleri Valladolid & Waringer, n. sp., based on morphological, genetic and ecological evidence.

The morphology of the larva, pupa, male, and female of Rhyacophila loeffleri Valladolid & Waringer, n. sp., from Austria, Czech Republic, France, and Italy is described. Data from molecular analysis are also provided, based on mitochondrial cytochrome c oxidase subunit I (mtCOI), including sequences from German and Swiss specimens, and compared with those of samples of the nominate species R. fasciata Hagen 1859, as well as with other species and subspecies in the Rhyacophila fasciata Species Complex: R. septentrionis McLachlan 1865, R. denticulata McLachlan 1879, R. sociata Navs 1916, R. kykladica Malicky & Sipahiler 1993, R. delici Kuini & Valladolid 2020, R. fasciata viteceki Valladolid & Kuini 2020 and R. macedonica Karaouzas, Valladolid & Ibrahimi 2022. Our study revealed morphological differences between R. fasciata and R. loeffleri, as well as genetic differences among the other taxa of the R. fasciata Complex, supporting the recognition of R. loeffleri as a new species. Also, Rhyacophila fasciata viteceki is recognized as a distinct species, R. viteceki (status promotus), based on results of the molecular analysis.