Mesogobius batrachocephalus

Common name. Knout goby.

Diagnosis. Distinguished from species of similar genera Neogobius and Ponticola in freshwaters in Black Sea basin by: ● 8–10 vertical rows of papillae in suborbital area (Fig. 60) / ● 72–85 total scales in midlateral series / ○ nape naked / ○ anterior naris not projecting forward beyond lip / ○ male without bluish-iridescent, small blotches on membrane of first dorsal. Size up to 345 mm SL.

Distribution . Black, Marmara and Azov Sea basins. Freshwaters in Georgia and European range. More records expected from coastal lagoons in Türkiye.

Habitat. Inshore habitats, estuaries, brackish and freshwater lagoons on sandy or rocky bottoms. Often very deep in summer (up to 100 m). Rarely in pure freshwater.

Biology. Lives up to 8 years. First spawns at 3 years in February–May, once a year. Eggs large, laid under or between rocks. Feeds mainly on fish.

Conservation status. LC.

Remarks. Mesogobius nonultimus (nape scaled) from the Caspian basin is usually listed as a subspecies of M. batrachocephalus . It is a distinct species that does not enter freshwater.

Further reading. Porumb 1961 (biology); Bănărescu 1964 (biology, distribution); Pinchuk et al. 2004b (biology).