Proterorhinus

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 675

Proterorhinus

All freshwater species of Proterorhinus have long been confused under the name P. marmoratus . Morphological and molecular data indicate that P. marmoratus does not enter pure freshwaters; it inhabits brackish waters in the Black Sea. Consequently, it is only mentioned in the key. Proterorhinus semilunaris also enters brackish waters and both may occur at similar salinities and may form hybrids. Three species occur in the Black Sea and two, potentially three, in the Caspian basin. All three Caspian species have been described from coastal habitats: P. nasalis and P. blennioides

from the Caspian Sea near Baku ( Azerbaijan) and P. semipellucidus from the mouth of the Karasu, a tributary of Gorgan Bay ( Iran). Proterorhinus nasalis from Azerbaijan and Russia and P. semipellucidus from Iran might be conspecific or two allopatric species. Much more research is needed on this genus and the situation might be quite different from what is presented here in summer 2025.

Further reading. Kessler 1877 (description of P. semipellucidus ); Neilson & Stepien 2009 (phylogeny with mixed-up names); Zarei et al. 2021 (phylogeny with mixed-up names); Vasil’eva et al. 2025 ( P. blennioides ).

Key to species of Proterorhinus in Black Sea basin

1a - Head length 24–28 % SL; 15–17. anal rays. ……………… P. marmoratus

1b - Head length 28–35 % SL; 13–14, rarely 16 anal rays. ………………2

2a - Head length 28–31 % SL; usually 14. anal rays. ……………… P. semilunaris

2b - Head length 31–35 % SL; usually 13. anal rays. ……………… P. victori

Key to species of Proterorhinus in Caspian Sea

1a - Eye diameter 16–21 % HL, as wide or smaller than interorbital space. ……………… P. blennioides

1b - Eye diameter 20–28 % HL, wider than interorbital space. ……………… 2

2a. Usually second 15–17½ branched rays in second dorsal fin; usually 13–15½ branched anal rays; 39–61 scales in midlateral series. ……………… P. nasalis

2b. Usually 14–15½ branched rays in second dorsal fin; usually 10–14½ branched anal rays; 36–45 scales in mid- lateral series. ……………… P. semipellucidus