Oxynoemacheilus frenatus

Oxynoemacheilus frenatus (Heckel, 1843)

(Figs. 10–11, Table 6)

Cobitis frenata Heckel, 1843

ZM-CBSU H2316, 15, 48–66 mm SL.; Iran: West Azerbaijan Prov.: Little Zab River a place between Piranshahr and Sardasht, 31°11’12” N 51°16’16” E.

The type locality of Cobitis frenata is “Tigris”, presumably at Mosul (Heckel 1843). Five syntypes are in the Naturhistorisches Museum Wien (NMW 48552) (Fig. 10).

Freyhof et al. (2011) as well as Freyhof & Özuluð (2017) treated O. afrenatus as a synonym of O. frenatus, and then identified fishes from the upper Tigris in Turkey as O. frenatus. Oxynoemacheilus afrenatus was described from small tributaries to the Tigris around the Turkish city of Diyarbakýr about 400 km upstream from Mosul.

Here, we found an oxynoemacheilid population from the Lesser Zab River drainage in Iran with an incomplete lateral line, reaching to a vertical between the pectoral-fin tip and the anal-fin origin and a mottled flank pattern without bars or large, vertically elongated blotches on the caudal peduncle and the prominent dark-brown stripe between the snout and the eye. These characters are also common in the syntypes of O. frenatus (Fig. 10).

Until 2014, oxynoemacheilid fishes from the Greater and Lesser Zab River drainages were identified as O. argyrogramma and O. frenatus. Kamangar et al. (2014) then described three species, O. chomanicus, O. kurdistanicus , and O. zagrosensis from the Choman River, a headwater stream of the Lesser Zab in the Iranian part of Kurdistan. Freyhof & Geiger (2017) following Kamangar et al. (2014), identified O. argyrogramma collected in the Iraqi part of the Lesser Zab as O. kurdistanicus. Freyhof & Geiger (2017) also considered the identified O. frenatus as O. chomanicus.

The newly discovered population of O. frenatus from the Lesser Zab River drainages in Iran is distinguished from O. chomanicus and O. zagrosensis by having an incomplete lateral line (vs. complete). They also formed separate clades in the phylogenetic tree based on the COI barcoding region (Fig. 1).

Oxynoemacheilus frenatus is distinguished from O. zarzianus from the Lesser Zab River drainage in Iraqi Kurdistan by having an incomplete lateral line (vs. complete) (see Freyhof & Geiger 2017). It is distinguished from O. gyndes from the upper Sirwan (Kurdish) drainage in Iraqi Kurdistan, by having a central pore in the supratemporal canal (vs. absent) and having an incomplete lateral line, reaching under the dorsal-fin base or above the anal-fin base (vs. very short lateral line reaching slightly behind the pectoral-fin base, not reaching the vertical through the dorsal-fin origin) (see Freyhof & Abdullah 2017).

Oxynoemacheilus frenatus is also distinguished from O. hanae from the upper Sirwan (Kurdish) drainage in Iraqi Kurdistan, by lake a suborbital groove in males (vs. present) (see Freyhof & Abdullah 2017).

Oxynoemacheilus frenatus is distinguished from O. kentritensis from Turkey, by having incomplete lateral line (vs. complete) and mottled or marbled pattern on the flank behind the dorsal-fin origin (vs. distinct bars or vertically elongated blotches) (see Freyhof et al. 2017).

Oxynoemacheilus frenatus is distinguished from O. hazarensis from Turkey by having scales on the back and flank in front of the anus (vs. scales absent) (see Freyhof & Özuluð 2017). Oxynoemacheilus frenatus and O. hazarensis also formed separate clades in the phylogenetic tree based on the COI barcoding region (Fig. 1), with 8% K2P COI sequence divergence.

We also included two available sequences that belong to Oxynoemacheilus from Turkey identified as O. frenatus in the phylogenetic tree (Fig. 1), which formed a separate clade from the Iranian part of the Lesser Zab population with 8% K2P COI sequence divergence.

It seems that the fishes from the upper Tigris River drainage in Turkey, which are identified as O. frenatus by Freyhof et al. (2017), belong to O. afrenatus and the new population from the Lesser Zab River drainages in Iran belongs to O. frenatus. In addition to molecular differentiation, these two populations are distinguished based on the colour pattern on the anterior part of the flank, which is interrupted by an unpigmented zone along the lateral line in fishes from Turkey (vs. not interrupted in from the Lesser Zab River drainages in Iran) (Fig. 11). Freyhof et al. (2017) also indicated this only difference between the fishes from the upper Tigris and the syntypes.