A new loach of the genus Oxynoemacheilus from the Tigris River drainage and its phylogenetic relationships among the nemacheilid fishes (Teleostei: Nemacheilidae) in the Middle East based on mtDNA COI sequences

Abstract

Oxynoemacheilus parvinae , new species, from the tributaries of the Iranian Sirvan River drainage, belongs to a group of Oxynoemacheilus having a suborbital groove in males and elongated body. It is distinguished from the other species of this group in the Tigris River drainage by a combination of the following characters: 8½-9½ branched dorsal-fin rays, large to medium dark-brown spots especially on the post-dorsal part, emarginated caudal fin, angular shape of bony capsule of swim bladder with developed posterior process, longer head and shallower body. It is also diagnosed from its nearest species ( O. bergianus and O. longipinnis ) by two fixed, diagnostic nucleotide substitutions in the mtDNA COI barcode region, and a K2P nearest-neighbour distance of 1.4% to O. longipinnis . Maximum Likelihood and Bayesian phylogeny reconstructed based on COI barcode region place the sequenced nemacheilid fish into a monophyletic clade which show between 1.4 % ( O. parvinae vs. O. longipinnis ) and 16.3 % ( O. longipinnis vs. O. merga ) K2P sequence divergence.