Chondrostoma esmaeilii, Eagderi, Jouladeh-Roudbar, Birecikligil, Cicek & Coad, 2017

Chondrostoma esmaeilii View in CoL View Figure

Common name. Ravansar nase.

Diagnosis. Distinguished from other species of Chondrostoma in Caspian, Persian Gulf, and Kor endorheic basins in Iran by: ● no cornified sheath covering lower lip / ○ mouth markedly arched both in juveniles and adults / ○ 8−9½, usually 8½, branched dorsal rays / ○ 10½ branched anal rays / ○ 51−58 total lateral-line scales / ● 15−17 gill rakers / ○ 6–6 pharyngeal teeth. Size up to 120 mm SL.

Distribution. Iran: Sarab-e Ravansar, a headwater of Seymareh, a tributary of Karkheh.

Habitat. Slow to moderate-flowing streams with muddy and sandy bottoms and dense riparian vegetation.

Biology. Feeds on periphyton scraped from hard substrate. No data.

Conservation status. CR; known only from a small population in a very small area. Desiccation of the river is a major threat, and the species may be at the edge of extinction.

Remarks. Mitochondrial DNA analysis places this species in C. regium , which is widespread in the region. The general morphology suggests that C. esmaeilii may be a hybrid between C. regium and Squalius verepi . As these two species have not been found in the range of C. esmaeilii (despite several attempts), this species is likely a stabilised species of hybrid origin that reproduces independently of its parental species. More research is needed to clarify the situation.

Further reading. Eagderi et al. 2017c (description).