Cornigerius lacustris of Lake Hazar, Turkey, a synonym of Cornigerius maeoticus (Pengo) of the Ponto-Caspian (Cladocera: Onychopoda)

摘要

Cornigerius species are endemic to the Ponto-Caspian, with the exception of Cornigerius lacustris, which is endemic to freshwater Lake Hazar in the Euphrates basin. However, the barcoding fragment of the cytochrome c subunit I (COI) of animals from the type locality shows less than 1 divergence with Black Sea and less than 2 with Caspian Lake C. maeoticus, the oldest and most widespread species of the genus. Black Sea and Caspian Lake animals show 1.5 divergence. We therefore place the origin of the Hazar population in the Black Sea. Combined with a variable morphology, we also conclude that C. lacustris is a synonym of C. maeoticus, as already suspected by its describer. Dating the 'lacustris' population is difficult, but it has been there for at least a century.