Two new species of the genus Hydropsyche Pictet, 1834 (Trichoptera, Hydropsychidae) from the Middle East and Caucasus ecoregions

The knowledge about the genus Hydropsyche Pictet, 1834 in the Middle East and Caucasus ecoregions is still scarce with several species described during the past years. In this paper, we describe two new species within the Hydropsyche guttata species cluster from several localities in the Middle East and Caucasus ecoregions. Hydropsyche hindrajab sp. nov. is reported from Azerbaijan, Iran and Türkiye, while Hydropsyche fitesa sp. nov. is reported from Iran. Males of these newly-discovered species are compared with their closest congeners: Hydropsyche iranica Malicky, 1977, H. sciligra Malicky, 1977 and H. tigrata Malicky, 1974. For Hydropsyche hindrajab sp. nov., we applied an integrative taxonomic approach combining morphological examination and molecular data, while Hydropsyche fitesa sp. nov. is described, based on morphological characters only. To elucidate phylogenetic and taxonomic relationships and to corroborate the distinctiveness of Hydropsyche hindrajab sp. nov., we analysed mitochondrial cytochrome c oxidase subunit I ( COI ) sequences and applied three species delimitation methods (ASAP, ABGD, bPTP). Although the two phylogenetic approaches yielded somewhat different topologies, all species delimitation analyses supported the recognition of Hydropsyche hindrajab sp. nov. as a distinct evolutionary lineage. This study contributes to the knowledge of the Hydropsyche fauna of the Middle East and Caucasus ecoregions and demonstrates the utility of integrative taxonomy in resolving species boundaries within morphologically close species complexes.