Resolving a 182-year-old taxonomic puzzle: Luciobarbus in the Persian Gulf basin (Teleostei: Cyprinidae)

The species diversity of the genus Luciobarbus in the Persian Gulf basin is revisited by integrating morphological, mitochondrial, and nuclear genomic data. Three species are recognised: Luciobarbus esocinus, L. schejch, and L. subquincunciatus. Barbus rajanorum is a hybrid between L. schejch and Capoeta damascina. Luciobarbus mystaceus described from the Caspian basin, and identified by Heckel (1843) as L. mystaceus from the Tigris and Qweiq are identified as L. schejch. Luciobarbus barbulus is a junior synonym of L. schejch. Luciobarbus kersin and L. schejch are likely conspecific, and as First Revisers, we give priority to L. schejch over L. kersin. The syntypes of L. xanthopterus are identified as hybrids between L. esocinus and L. schejch, the species name xanthopterus is unavailable, and L. xanthopterus was already treated as a synonym of L. schejch. Fishes identified as L. barbulus, L. pectoralis, and L. xanthopterus in the Euphrates and Tigris drainages are all L. schejch. Luciobarbus pectoralis is endemic to the Mediterranean basin. Luciobarbus esocinus and L. schejch cannot be identified by their mtDNA as they have widely hybridised. Luciobarbus schejch hosts two types of mtDNA; few are species-specific, but most individuals have the mtDNA of L. esocinus. The genome-wide SNP data produced for L. esocinus and L. schejch confirms the existence of two genomic clusters (L. esocinus and L. schejch), demonstrating a variable extent of hybridisation between both, and agreeing with their variable morphology.