Mystus cyrusi, a new species of bagrid catfish (Teleostei: Bagridae) from Middle East.

Mystus cyrusi, new species, is described from the Kol River drainage which flows to the Straits of Hormuz in southern Iran. It is distinguished from its closest relative, Mystus pelusius from the Tigris-Euphrates River system by a combination of characters: The maxillary barbel short, not reaching to beyond pelvic fin (vs. extends as far as anal fin in some female M. pelusius), shorter adipose fin (30.837.4% SL) and with a steeper sloping at its origin vs. longer (37.645.6% SL) and with a more gently sloping in M. pelusius), greater head depth (16.6421.9% SL vs. 12.616.59% SL in M. pelusius), greater caudal-peduncle depth (10.312.5% SL vs. 8.710.5% SL in M. pelusius) and fewer total gill rakers (1214, mode 12) vs. (1417 in M. pelusius). Mystus cyrusi is also well distinguished by molecular characters. Genetically, M. cyrusi shows the lowest genetic distance with M. pelusius (4.6%), and then with M. singaringan (11.6%), M. wolffii (13.1%), and M. bleekeri (13.4%) among the 21 studied species in their mtDNA sequences. Mystus cyrusi shows the highest genetic distance with M. montanus (26.5%).