Can be distinguished from other species of Cottus in Europe by possessing a shallow transverse groove in the snout between the anterior and posterior nares and the combination of the following characters: genital papilla lobular in males; depth of caudal peduncle 20-24% HL; length of caudal peduncle 41-64% HL; prickling on body extending backwards to caudal peduncle (reduced or sometimes absent in some populations); absence of distinct transverse bands on pelvic fin; predorsal length 32-37% SL; distance from tip of snout to origin of second dorsal fin 50-52% SL; dorsal head length 21-25% SL; unique molecular markers (Ref. 55856).