Cyprinion tenuiradius, Heckel, 1847

Cyprinion tenuiradius View in CoL View Figure

Common name. Persian lotak.

Diagnosis. Distinguished from other species of Cyprinion in Persian Gulf and Iranian endorheic basins by: ○ mouth wide, variably arched to straight / ○ no lateral lobes or pad on lower lip or small lateral lobes present / ○ 10−21 gill rakers / ○ 32−39, usually 34−38, total lateral-line scales / ○ last unbranched dorsal ray thin, flexible along at least upper third, usually serrated from half to two-thirds of length / ○ posterior dorsal margin about straight or slightly concave / ○ with or without orange spots along lateral line / ○ 11−15½, usually 12−14½, branched dorsal rays / ○ back in front of dorsal with naked median strip of variable length and about one scale wide / ○ scales on belly and upper anterior flank variably imbricated and often small and embedded in skin or absent. Size up to 130 mm SL.

Distribution View Figure . Iran: Persian Gulf basin from Helleh to Kol drainages, and Kor endorheic basin.

Habitat. A wide range of streams and rivers.

Biology. No data.

Conservation status. LC.

Remarks. Cyprinion tenuiradius occurs between the range of C. macrostomum in the north and C. microphthalmum in the south. It is also morphologically intermediate between these two species, with populations more or less resembling C. macrostomum or C. microphthalmum , often making identification difficult. Furthermore, C. tenuiradius shares its mtDNA with C. macrostomum or C. microphthalmum , and no species-specific mtDNA characters have been found so far. It is expected that C. tenuiradius has its evolutionary origin in hybridisation of C. macrostomum and C. microphthalmum , and the species’ distribution area is a wide hybrid zone between two parental species. We accept it as a species of hybrid origin, a problematic position that needs to be studied in more detail.

Further reading. Bănărescu & Herzig-Straschil 1995 (description); Teimori et al. 2010 (distribution); Nasri et al. 2018 (morphology).