Oxynoemacheilus

Freyhof, Jörg, Kaya, Cüneyt, Turan, Davut & Geiger, Matthias, 2019, Review of the Oxynoemacheilus tigris group with the description of two new species from the Euphrates drainage (Teleostei: Nemacheilidae), Zootaxa 4612 (1), pp. 29-57 : 34

Key to species of Oxynoemacheilus in the Euphrates and Qweik River drainages and the Lake Van basin

Loaches identified as O. samanticus by their COI barcode sequence are excluded from the key as their morphological differentiation from O. bergianus is the subject of a separate study.

1a Lateral line incomplete, terminating anterior to dorsal-fin origin or above anal-fin base.............................. 2

1b Lateral line complete, reaching to caudal-fin base............................................................ 5

2a Flank with distinct bars; an upper and a lower black spot at caudal-fin base; caudal peduncle with long, high dorsal adipose crest; crest with whitish margin, reaching beyond vertical through anal-fin origin, usually below last dorsal-fin rays when folded down; flank with isolated and deeply embedded scales............................................. O. tigris

2b Flank with a mottled, marbled or marmorate pattern, often with narrow, indistinct bars on caudal peduncle or a series of darkbrown blotches; colour pattern on caudal-fin base not differentiated from flank pattern, with or without a black bar, never with two black spots; caudal peduncle without or with a short dorsal-adipose crest, crest without white margin, reaching to middle of caudal peduncle or to vertical through anal-fin base; flank without scales........................................3

3a A central pore in supratemporal canal; a bold bar on caudal fin-base, usually M-shaped, fused with a roundish or vertically elongate, dark-brown blotch at vertical midline; caudal fin usually with wide, bold, dark-brown bands........ O. arsaniasus

3b No central pore in supratemporal canal; a mottled pattern on caudal-fin base, without bold bar; caudal fin with narrow, indistinct, pale-brown bands..................................................................................4

4b Caudal-peduncle length 1.0–1.3 times its depth; body width at dorsal-fin origin 13-17% SL¸ dorsal adipose crest on caudal peduncle high, not reaching to vertical through last anal-fin ray base in individuals larger than 50 mm SL...... O. ercisianus

4a Caudal-peduncle length 1.3–1.6 times its depth; body width at dorsal-fin origin 11–13% SL; dorsal adipose crest on caudal peduncle shallow, reaching to vertical through last anal-fin ray base in individuals larger than 50 mm SL......... O. muefiti

5a Suborbital groove or flap absent in male.................................................................... 6

5b Suborbital groove or flap present in male................................................................... 7

6a Caudal peduncle without adipose crest or ridge; flank with a distinct midlateral series of large, roundish or horizontally elongated brown blotches and a row of small brown blotches between upper pelvic-fin base and lowermost caudal-fin base............................................................................................... O. paucilepis

6b Caudal peduncle with a wide, often long adipose ridge; flank with a brown mottled or marmorate pattern, with irregularly shaped brown bars, especially on flank behind dorsal-fin origin in some individuals......................... O. kaynaki

7a Caudal fin slightly emarginate.................................................................. O. araxensis

7b Caudal fin deeply emarginate or slightly forked............................................................. 8

8a A bold upper and a lower black blotch or spot on caudal-fin base, often overlaid by a dark-brown or black chevron-shaped bar................................................................................................. 9

8b One central or no bold black blotch on caudal-fin base............................................... O. bergianus

9a Flank and caudal peduncle with marbled colour pattern, without bars; caudal peduncle depth 1.4–1.8 times in caudal peduncle length................................................................................ O. argyrogramma

9b Caudal peduncle, and in some individuals also flank, with bars; caudal peduncle depth 2.0–2.8 times in caudal peduncle length................................................................................... O. euphraticus