Luciobarbus, Heckel, 1843

Luciobarbus View in CoL View Figure

Luciobarbus are medium to large fishes that often co-occur with superficially similar Barbus and Capoeta species. Luciobarbus are less rheophilic and prefer more stagnant habitats than sympatric Barbus . In West Asia, all but one Luciobarbus species can be readily distinguished from Barbus species by their uniform yellowish, brown, or grey colouration, sometimes with an indistinct lateral stripe (vs. body and fins covered with distinctive, irregularly shaped spots and blotches), and by the presence of large nuptial tubercles on the snout (vs. very small nuptial tubercles throughout the head). Juveniles of both genera show a pattern of dark-brown blotches on the body and are difficult to distinguish at first sight. Luciobarbus can also be immediately distinguished from Capoeta by the absence of a keratinised lower jaw (vs. present in most species), a long, pointed head (vs. short and roundish), and the presence of two pairs of barbels (vs. usually one pair). Luciobarbus and Capoeta often hybridise. Some Luciobarbus , such as L.pectoralis and L. schejch , show a polymorphic lower lip, with a pendulous central lobe and fleshy lips in some individuals, and an interrupted lower lip with a hard and exposed lower jaw in other individuals, including all intermediate lip shapes. This polymorphism has been misinterpreted as species diagnostic, and individuals with a fleshy lobe on the lower lip have often been identified as L. barbulus (= L. schejch ) throughout West Asia. In contrast, individuals without such a lobe have been identified as L. pectoralis . Both species are strictly allopatric, and both lip forms are found in both species. The lip shape is not variable in other Luciobarbus , such as L. esocinus and L. subquincunciatus . Furthermore, Luciobarbus species exhibit significant allometric growth in body shape and the length and strength of the last unbranched dorsal ray. This has led to some taxonomic confusion, particularly in the Persian Gulf basin.

The identification of Luciobarbus species in the large rivers of the Euphrates and Tigris drainages has only recently been resolved. Luciobarbus esocinus and L. subquincunciatus are two well-differentiated species, L. schejch often hybridises with L. esocinus . Individuals cannot be identified by their COI DNA sequence alone, as they may have their own or the mtDNA of L. esocinus . Fish commonly identified as L. barbulus or L. xanthopterus all belong to L. schejch . The syntypes of L. xanthopterus have been identified as hybrids of L. esocinus and L. schejch , and this name is not available for any of the species.

Further reading. Freyhof et al. 2025 (revision).

Keys to species of Luciobarbus in West Asia

Caspian basin and Hari drainage

Differences between L. capito (Caspian basin) and L. conocephalus (Hari & Aral basin) need to be better understood, and future research will require more effort. Molecular data support both as distinct species.

1a - Predorsal length shorter than postdorsal length; 7½ branched dorsal rays; 16–25 gill rakers. ……………… L. brachycephalus

1b - Predorsal length equal to or longer than postdorsal length; 8½ branched dorsal rays; 10–19 gill rakers. ………………2

2a - Lips very thick, lower lip with a median lobe or pad; 83–103 total lateral-line scales; back not or slightly compressed in front of dorsal origin; colouration of back and belly not sharply contrasted. ……………… L. mursa

2b - Lower lip very thin, interrupted in middle, without fleshy middle lobe; 52–72 total lateral-line scales; back between head and dorsal origin laterally compressed, forming a keel; sharp contrast between dark-brown or yellowish back and whitish or yellow belly in large individuals. ……………… L. capito / L. conocephalus

Mediterranean basin

1a - 43–48 total lateral-line scales. ……………… L. graecus

1b - 48–63 total lateral-line scales. ………………2

2a - 48–58 total lateral-line scales. ……………… L. pectoralis

2b - 55–63 total lateral-line scales. ……………… L. longiceps

Persian Gulf basin

1a - Numerous large, roundish, dark-brown, or black blotches on head, body, and fins arranged in an almost quin- cunx pattern; 75–88 total lateral-line scales. ……………… L. subquincunciatus

1b - Body plain yellow, grey; or silvery or back and upper part of body brown and lower body yellow or silvery; irreg- ularly shaped, small pale-brown spots and blotches present in juveniles 45–73 (78) total lateral-line scales. ………………2

2a - Head pike-like, strongly pointed, depressed; mouth almost terminal or terminal; snout length 2.0–2.9 times in postorbital length in individuals larger than 150 mm SL; 8–11 total gill rakes; 60–73(–78) total lateral-line scales; juveniles often with many, small dark-brown spots on upper flank. ……………… L. esocinus View Figure

2b - Head barbel-like, not strongly pointed or depressed; mouth inferior in small individuals, inferior or subterminal in large individuals; snout length 1.1–1.9 times in postorbital length; 11–24 total gill rakes; 50–62 total lateral-line scales; juveniles without small dark-brown spots on upper flank. ……………… L. schejch