Origin and Relationships of Humpback Whitefishes of Mongolia (Corgoninae)

Abstract

Questions of the evolution and taxonomic status of the humpback whitefish Coregonus pidschian and its relationships with the complex C. lavaretus sensu lato (s.n.) are as of yet unresolved problems in the study of Coregonus fauna. With the exception of the Amur basin, the only representatives of the genus Coregonus in native Mongolian fauna are humpback whitefishes (Kottelat, 2006; Dulmaa, 2015). The taxonomic status and origin of the previously described forms found in Mongolia require clarification. The study analyzes their relationships with other representatives of the Coregonus genus using phylogenetic reconstruction based on the mtDNA cytochrome b gene. It is discovered that there are two divergent mtDNA lines of humpback whitefishes coexisting in lakes of the Darkhad Depression. A potential history of their migration to Lake Dood Tsagaan through the upper reaches of the Yenisei River is proposed. The hypothesis of the Darkhad Depression being a refugium that gave birth to a quick-growing form of the Issatchenko whitefish (C. fluviatilis Isaczenko, 1925, Yenisei basin), separate from the C. lavaretus complex, is disproven. It is shown that a form conspecific with the Issatchenko whitefish definitely occurs on the territory of Mongolia, but only in the Selenga River basin, from where its range extends throughout the Angara–Yenisei basin to the Nizhnyaya Tunguska.