Chondrostoma, Agassiz, 1835

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 331-332

Chondrostoma

A genus of middle-sized to large Leuciscids, found from France to the Volga, and Iran. Together with the Anatolian Turcichondrostoma , they are related to the west European genera Achondrostoma , Iberochondrostoma , Pseudochondrostoma , Parachondrostoma , and Protochondrostoma , which all form one monophyletic lineage. All nases are also related to the European Leuciscid genera Phoxinellus and Telestes and the West Asian genus Pseudophoxinus , although the precise phylogenetic relationships between these groups remain unclear.

In West Asia, 11 out of 12 species of Chondrostoma are characterised by a well-developed rostral cap covering most of the upper lip and a variably developed cornified cutting edge on the lower jaw. Chondrostoma are slender fishes that inhabit fast-flowing waters near or on stone bottom. They obtain their food by scraping algae growing on stones and rocks and invertebrates living among them, which we refer to as “aufwuchs” (literally, ‘growth’). Adults have an inferior mouth with a cornified sheath covering the lower lip, often with a sharp edge. In some species, the mouth is arched, as in most leuciscids. In more specialised species, the anterior edge of the lower lip (bearing the cornified sheath) is straight. In such species, the lower lip is distinctly fleshy only at the corners of the mouth, and the cornified sheath appears as a blade. The mouth morphology changes during ontogeny and all species with a straight mouth in adults have an arched mouth when they are juveniles. In West Asia, all Chondrostoma are difficult to distinguish, and many species are very closely related. The published diagnoses of several species do not provide an effective means of differentiating them. Consequently, the following keys are presented as a provisional guide only. Given their close phylogenetic relationship, future studies are anticipated to reveal some of the species to be conspecific.

Further reading. Elvira 1987 (revision); Robalo et al. 2007 (phylogeny); Geiger et al. 2014 (phylogeny); Çiftçi et al. 2020 (phylogeny).

Keys to species of Chondrostoma in West Asia

Aegean, Marmara, and Black Sea basins

1a - Usually 9, rarely 8, branched pelvic rays. ………………2

1b - Usually 8 branched pelvic rays. ………………3

2a - Usually 8½ branched dorsal rays; usually 9½ branched anal rays. ……………… C. nasus

2b - Usually 9½ branched dorsal rays; usually 10½ branched anal rays. ……………… C. colchicum

3a - Lateral line with 44–54 total lateral line scales. ……………… C. turnai

3b - Lateral line with 52–69 total scales. ………………4

4a - 52−60 total lateral line scales. ……………… C. meandrense

4b - 60−69 total lateral line scales. ……………… C. holmwoodii

Central Anatolia and Mediterranean basin east of Antalya

1a - 32−40 gill rakers. ………………2

1b - 24−35 gill rakers. ………………3

2a - A prominent keel on back in front of dorsal. ……………… C. beysehirense

2b - No keel on back in front of dorsal. ……………… C. kinzelbachi

3a - Keel between anus and posterior pelvic base absent or very poorly developed; sheath covering lower lip strongly cornified. ……………… C. toros

3b - Keel between anus and posterior pelvic base shallow but well developed; sheath covering lower lip poorly cornified. ……………… C. ceyhanense

Caspian, Persian Gulf, and Kor endorheic basin in Iran

1a - 15–17 gill rakers; no cornified sheath covering lower lip. ……………… C. esmaeilii

1b - (17) 25–34 gill rakers; a cornified sheath covering lower lip. ………………2

2a - Mouth cleft strongly arched; cornified sheath cover- ing lower lip very thin. ……………… C. cyri

2b - Mouth cleft straight or slightly arched; cornified sheath covering lower lip thick. ……………… C. regium