Mesopotamian chub

biology_ecology

Habitat. Small- to medium-sized streams, mostly in mountains and hilly areas. Biology. No data.

Handbook of Freshwater Fishes of West Asia

diagnosis

Diagnosis. Distinguished from S. lepidus in Persian Gulf basin by: ● upper lip projecting beyond lower lip / ● posterior anal-margin convex / ● 39 – 46 + 1 – 2 lateral-line scales / ● head blunt / ● snout short / ● dorsal head profile straight or slightly convex / ● scale pockets along lateral midline densely covered by pigments forming a large grey or black crescent-shaped blotch, resulting in a very contrasted reticulate pattern / ● anal rays orange in life / ● anal with few or without black pigments in preserved individuals / ● head length 26 – 30 % SL / ● interorbital distance 37 – 45 % HL / ● head depth 65 – 71 % HL / ● posteriormost point of anal at tip of 3 rd or 5 th branched rays. Size up to 450 mm SL.

Handbook of Freshwater Fishes of West Asia

discussion

Remarks. In medium-sized rivers often in sympatry with S. lepidus, which inhabits mostly large rivers. Both species occasionally hybridise as mitochondrial DNA of S. lepidus is often found in S. berak, and there are populations with intermediate morphological character states. Individuals “ difficult to identify ” by characters given could be such hybrids. Squalius semae from the upper Euphrates is a synonym. Characters proposed to distinguish S. verepi from the upper Tigris from S. berak could also not be confirmed and both are also indistinguishable by their COI sequences. Few genomic data however indicate that S. verepi might be a valid species.

Handbook of Freshwater Fishes of West Asia

discussion

Taxonomic notes. Squalius berak hybridizes with S. lepidus (Khaefi et al. 2016) and some Squalius populations might represent hybrids in most cases, all individuals can be identified without problems.

A Critical Checklist of the Inland Fishes Native to the Euphrates and Tigris Drainages