Squalius turcicus, De Filippi, 1865

Squalius turcicus View in CoL View Figure

Common name. South Caspian chub.

Diagnosis. Distinguished from other species of Squalius in Persian Gulf, Caspian, Lake Namak and Lake Urmia basins by: ● anal membranes and rays hyaline, greyish-white or yellow in life / ○ mouth terminal or subterminal in adults / ○ snout pointed / ○ knob on lower jaw symphysis narrow, thin or absent / ○ head length 26–28 % SL / ○ interorbital distance 35–41 % HL / ○ head width at nape 61–70 % HL / ○ anterior width 4.2–7.1 times in its lateral length / ○ (7½) 8½ (9½) branched anal rays / ○ 7–11 gill rakers / ○ anal height 18–24 % SL / ○ posterior tip of flank scales without bold blotch / ○ posteriormost point of anal at tip of 5 th or 6 th anal branched ray / ○ a wide band of densely-set, dark-brown or blackish melanophores along posterior margin of each flank scale. Size up to 264 mm SL.

Distribution View Figure . Caspian basin from Aras east to Atrak. Also, in Lake Urmia basin ( Iran), Cheshme Ali in Western Kavir basin ( Iran), Sulak drainage (Dagestan), and uppermost Choman (Tigris drainage), directly at watershed to Saqez (Urmia).

Habitat. Wide range of streams and rivers, mostly in hilly areas. In lakes, from where it migrates to tributaries to spawn. Locally spawns on wave-washed lake shores on gravel substrate.

Biology. Lives up to 8 years, possibly longer. First spawns at 2–3 years (males) and 3–4 years (females). Spawns late May–July at water temperatures of 12–18°C.

Conservation status. LC.

Remarks. Molecular data suggest that this species is closely related to S. orientalis from the eastern Black Sea basin, and both may be conspecific. However, S. turcicus usually has dark-grey fins, whereas S. orientalis has orange fins, and the prominent vertical black bar behind the opercle in S. orientalis is absent in S. turcicus . Further research is needed to determine whether this is one or two species. Molecular characters differentiate the Kura and Aras chubs well. The species from the Kura is identified as S. agdamicus , and the one from the Aras is S. turcicus , but their morphological characters still need to be better studied. More research is required to distinguish the two species and understand their range.

Further reading. Bayçelebi 2019 (description, distribution).