Oxynoemacheilus brandtii

Common name. Caucasian loach.

Diagnosis. Distinguished from other species of Oxynoemacheilus in Caspian basin by:● caudal forked, usually with 1–3, wide and very bold bands / ○ an upper and a lower bold, black or dark-brown blotch on caudal base, usually fused into a bar, its colour distinctly darker than bars on caudal peduncle / ○ flank with wide, irregularly shaped bars, much wider than interspaces / ○ bars on caudal peduncle not interrupted in size and shape at or above lateral midline, rarely with a mottled pattern / ○ suborbital groove present in male / ○ caudal– peduncle depth 2.5–3.2 times in its length. Size up to 70 mm SL.

Distribution. Kura and Aras drainages.

Habitat. Fast to very fast-flowing streams and rivers with gravel or rock substrate. Usually found in riffles and rapids in middle of river.

Biology. No data.

Conservation status. LC.

Remarks. Populations studied from the Aras drainage share their mtDNA sequence with O. elsae but are identified as O. brandtii by morphological characters. Nemacheilus brandtii gibbusnazus from the upper Alazani in Georgian Kura drainage has been treated as a synonym, but the identity of this population may require further investigation.

Further reading. Kessler 1877 (description); Berg 1949b (description); Kaya et al. 2020a (distribution); Freyhof et al. 2021b (diagnosis, distribution).