Cyprinion kais, Heckel, 1843

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 165-166

Cyprinion kais

Common name. Smallmouth lotak.

Diagnosis. Distinguished from other species of Cyprinion in Persian Gulf and Iranian endorheic basins by: ● mouth semi-circular with two large lateral lobes on lower lip / ○ pelvic origin below or in front of dorsal origin / ● finger-like lower jaw with a papillious central pad / ○ 10–15 gill rakers on lower branch of first arch / ○ pelvic origin below dorsal origin / ○ no black spots or speckles on gill cover.Size up to 210 mm SL.

Distribution. Qweiq,Euphrates,Tigris,and Karun drainages.

Habitat. Usually rheophilic in fast-flowing waters in rapids and riffles. Less common in slow-flowing rivers and reservoirs.Rare in small streams and absent from cold headwaters.

Biology. No data.

Conservation status. LC; extirpated from Qweiq.

Remarks. Usually syntopic with C. macrostomum . Juveniles of both species are quite similar. Mitochondrial data suggest that C. kais is completely introgressed by C. macrostomum , having lost its own mitochondrial bodies. It has even been interpreted as a trophic, neotenic morphotype of C. macrostomum . However, the position of fins, the nuptial tubercles, and the colour pattern are so different that there is no doubt that they are two separate species.

Further reading. Kafuku 1969 (morphology); Bănărescu & Herzig-Straschil 1995 (morphology, distribution); Coad 2010a (overlap with C. macrostomum ); Daştan et al. 2012 (genetic diversity); Kaya et al. 2016 (distribution); Keivany et al. 2016 (distribution); Nasri et al. 2018 (morphology); Coad 2021a (biology, morphology).

Cyprinion macrostomum ; Tigris drainage, Türkiye; ~ 100 mm SL. Cyprinion macrostomum ; Lesser Zab drainage, Iraq; 150 mm SL.