This species is distinguished from its congeners in the Aegean and Marmara Sea basins by the following set of characters: small size (maximum size 5.7 cm SL) (vs. at least about 7.0 cm SL,

except O. theophilii); flank with 4-8 irregularly shaped narrow black bars posteriorly and a marbled pattern anteriorly (vs. more or less irregularly shaped dark brown or pale brown blocks or bars on flank in O. angorae, O. germencicus, O. eliasi, O. simavicus, O. theophilii) in most individual, body with vermiculated pattern in O. marmaraensis); a somewhat slender body and caudal peduncle; suborbital groove in males; an axillary lobe at base of pelvic fin; adipose crest on lower and upper parts of caudal peduncle absent (Ref. 131069).