Oxynoemacheilus simavicus (Balik & Banarescu, 1978)

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 533-535

Oxynoemacheilus simavicus

Common name. Mysian loach.

Diagnosis. Distinguished from other species of Oxynoemacheilus in Marmara and Black Sea basin by: ○ caudal– peduncle depth 6–10 % SL, usually 2.0–3.0 times in its length, very rarely 1.7–3.3, without high adipose crest or ridge / ○ caudal emarginate, middle caudal ray 70–96 % of length of longest ray in upper caudal lobe / ○ lateral line complete / ○ flank covered by scales / ○ suborbital groove present in male / ○ one central or no black, grey or brown blotch or short bar on caudal base, its colour identical to blotches on caudal peduncle / ○ no yellowish triangles at posteriormost portion of caudal peduncle / ○ pelvic very long, reaching or almost reaching to anus / ○ pectoral in male very long, reaching or

almost reaching to pelvic origin /○ flank mottled or with large irregularly shaped, squarish or vertically elongate blotches, usually as wide or narrower than interspaces / ○ lateral blotches on caudal peduncle usually interrupted in size and/ or shape at or above lateral midline. Size up to 74 mm SL.

Distribution. Türkiye: Susurluk, Sakarya and Büyük Melen drainages.

Habitat. Moderately fast-flowing water in streams and rivers with gravel substrate. Usually found in riffles and other fast-flowing habitats.

Biology. No data.

Conservation status. LC.

Remarks. No external characters are known to distinguish this species from O. banarescui , O. bergianus , and O. fatsaensis , all of which are diagnosed by molecular characters. Morphological characters and differences in colour pattern to distinguish this species from the others are based on too small sample sizes or are false. As these four species are allopatric, the range should help in identification. Oxynoemacheilus sakaryaensis and O. melenicus are synonyms of this species as they are closely related, and none of the characters proposed as diagnostic in their description could be confirmed. The diagnostic characters distinguishing O. simavicus , O. sakaryaensis , and O. melenicus have been deliberately falsified to allow populations that differ slightly in molecular characters to be described as separate species.

Further reading. Balık & Bănărescu 1978, in Bănărescu, Nalbant & Balık 1978 (description); Erk’akan et al. 2014 (size); Freyhof 2022 (revision of O. bergianus group); Turan et al. 2023 (description of O. sakaryaensis and O. melenicus ).

Streams in lower Seyhan drainage are habitats of Oxynoemacheilus seyhanicola .

Oxynoemacheilus theophilii ; Bakırçay, Türkiye; 65 mm SL.