Abstract
The mayflies of the genus Epeorus Eaton, 1881 subgenus Caucasiron Kluge, 1997 are distributed from the eastern Mediterranean to the mountains of south-west China. In contrast to the Caucasus, the Mediterranean and Irano-Anatolian regions, where E. (Caucasiron) represents one of the most extensively studied mayfly taxa, the species diversity in the more eastern mountains of Asia has been studied only sporadically. In this study, the species diversity of E. (Caucasiron) from the mountains of Central Asia (Pamir, Tian Shan) and the western part of the Himalayas was analysed using DNA barcoding and the morphology of larvae and adults. The distance- and phylogenetic tree-based molecular species delimitation analyses revealed five E. (Caucasiron) species occurring in the study area. Three of them did not correspond morphologically to any known species of the genus Epeorus. These species were described herein as E. (C.) himalayensis Hrivniak & Sroka, sp. nov., E. (C.) lanceolatus Hrivniak & Sroka, sp. nov. and E. (C.) lineatus Hrivniak & Sroka, sp. nov. All new species were compared with other representatives of the subgenus and other related species of the genus Epeorus, and appropriate morphological diagnostic characters were provided. Morphological revision, main diagnostic characters, and information on the distribution of E. (C.) guttatus Braasch & Soldán, 1979 and two other potentially related Epeorus species from the area, E.psi Eaton, 1885 and E.suspicatus (Braasch, 2006), are also given.