Oxynoemacheilus zarzianus can be diagnosed from all its congeners in Tigris drainage by a combination of non-unique characters: a member of the species group (Oxynoemacheilus chomanicus, O. frenatus, O. gyndes; O. hazarensis, O. kentritesensis, O. kiabii, O. zagrosensis) which have no suborbital groove in males (vs. present in O. bergainus, O.. euphraticus; O. hanae, O. longipinnis, O. karunensis, O. kurdistanicus and O. parvinae) and slightly emarginate or truncate caudal fin (deeply emarginate or forked in O. chomanicus, O. frenatus, O. gyndes; O. hazarensis, O. kentritesensis, O. kiabii, O. zagrosensis) which have no suborbital groove in males (vs. present in O. bergainus, O.. euphraticus; O. hanae, O. longipinnis, O. bergainus, O. euphraticus; O. hanae, O. longipinnis, O. karunensis, O. kurdistanicus and O. parvinae) (Ref. 115565).