Squalius pursakensis (Hanko, 1925)

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 416-417

Squalius pursakensis

Common name. Sakarya chub.

Diagnosis. Distinguished from other species of Squalius in Western and Central Anatolia by: ○ dorsal origin behind vertical of last pelvic ray / ○ posteriormost point of anal at tip of 7 th or 8 th branched ray / ○ 14–15 circumpeduncular scales / ○ 8½, very rarely 9½ anal rays / ○ anal rays hyaline in live and preserved individuals / ○ anal membranes black, rarely orange in live, blackish in preserved individuals / ○ upper lip usually projecting beyond lower lip, lips at same level or lower lip projection in some individuals / ○ upper and ventral head profile straight in individuals larger than 100 mm SL / ○ snout conical and pointed / ○ scale pockets on flank with a dark-grey, crescent-shaped mark / ○ belly between anus and posterior extremity of pelvic base slightly or not compressed / ○ eye diameter 1.7–2.1 times in interorbital distance, 18–23 % HL /○ head length 25–29 % SL / ○ head depth at nape 63–67 % HL / ○ 40–46 total lateral-line scales. Size up to 380 mm SL.

Distribution. Türkiye: Sakarya drainage, likely restricted to upper and middle parts, including Porsuk and Kirmir. Also, in Lakes Eber, Akşehir, and Ilgın basins.

Habitat. A wide range of streams and rivers, mostly in hilly areas. In reservoirs, from where they migrate to tributaries to spawn on gravel substrate.

Biology. Lives up to 10 years. Spawns April–June.

Conservation status. LC.

Squalius pursakensis ; Lake Eber basin, Türkiye; ~ 190 mm SL.

Remarks. Squalius recurvirostris from Eber, Akşehir, and Ilgın lakes is a synonym as it is indistinguishable from S. pursakensis by COI DNA sequences, and morphological characters proposed to distinguish both species could also not be confirmed. Squalius pursakensis and mtDNA haplotypes of S. cappadocicus are found in the Sakarya. It has not yet been investigated where exactly both species occur in Sakarya, possibly in different subsystems, or where exactly hybrids between S. pursakensis and S. cappadocicus occur. In addition, the morphological characters distinguishing S. pursakensis and S. cappadocicus are poorly understood and require further research.

Further reading. Özuluğ & Freyhof 2011 (re-description).

Squalius turcicus ; Aras drainage, Türkiye; ~ 190 mm SL. © M. Özuluğ. Squalius turcicus ; Cheshme Kile, Caspian basin, Iran; ~ 260 mm SL.