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This species is distinguished from O. arsaniasus by not having a central pore in the supratemporal canal (vs. present); with mottled colour pattern on the caudal-fin base (vs. a bold bar, usually fused with a roundish or vertically elongate, dark-brown blotch at the vertical midline); fine, brown, mottled colour pattern on the flank, usually organised in narrow, pale-brown bars on the flank behind the dorsal-fin base (vs. flank marmorate, often with a midlateral series of large, bold, dark-brown, very irregularly shaped blotches or short bars); bars on caudal peduncle not separated from the adjacent saddles on the back (vs. separated); narrow, pale-brown, indistinct bands on the caudal fin (vs. usually bands wide, bold and dark-brown).
It differs from O. ercisianus by the longer and more slender caudal peduncle, the caudal peduncle length 1.3-1.6 times its depth (vs. 1.0-1.3) in individuals larger than 5.0 cm SL; narrower body, its body width at dorsal-fin origin 11-13% SL (vs. 13-17); a shallow dorsal adipose crest on the caudal peduncle reaching to the vertical through the base of the last anal-fin ray in individuals larger than 5.0 cm SL (vs. higher crest, not reaching to the vertical through the base of the last anal-fin ray base in individuals larger than 5.0 cm SL).
It differs from O. hazarensis with suborbital groove in the male absent (vs. present); no scales on the caudal peduncle (vs. with scales); shorter outer rostral barbel, 20-34% HL (vs. 34-41); shorter maxillary barbel, 25-33% HL (vs. 32-40).
It differs from O. kaynaki with lateral line incomplete (vs. complete); pelvic axillary lobe absent (vs. present); no scales (vs. present); bold, black bar at the caudal fin origin absent (vs. present).
It differs from O. tigris by having a mottled flank pattern without bold bars (vs. 10-16 bold bars, very prominent on the caudal peduncle); bold, black spots at the upper and lower caudal-fin base absent (vs. with 2 bold, black spots in most individuals); no scales (vs. present).
It further differs from the other species inhabiting the Euphrates drainage not belonging to the O. tigris species group by the following: distinguished from O. araxensis with suborbital groove in the male absent (vs. present); lacking scales (vs. present); differs from O. argyrogramma, O. bergianus, O. euphraticus, O. samanticus by having a slightly emarginate caudal-fin (vs. deeply emarginate or slightly forked); suborbital groove in the male absent (vs. present); no scales (vs. present), and no black spots at the caudal-fin base (vs. two bold black jet spots in O. argyrogramma, O. euphraticus); differs from O. paucilepis with lateral line incomplete (vs. complete), no scales (vs. flank covered by often isolated scales) (Ref. 120397). |