Morphological and Genetic Identification of Harpacticella inopinata (Harpacticoida, Copepoda) from Lake Baikal and the Yenisei River (Russia)

The results of studies of the morphology and genetics of the Baikal subendemic ( Harpacticella inopinata Sars, 1908 harpacticoid) are presented. The collections of 1969 and 2017–2022 from the southern part of Lake Baikal and the Yenisei River within the city of Krasnoyarsk are used as material. It is demonstrated that morphological variability within the species is most pronounced in the structure of the antenna exopodite and the number of pores and sensilla on the integument of thoracic somites. The genetic variability of the studied H. inopinata sample is described by three clades with an average distance between them of 0.24; genetic distances between individuals within the detected genetic groups do not exceed 0.005. It is found that H. inopinata from geographically distant habitats (Lake Baikal and the Yenisei River) form a single morphological and genetic group. The analysis of genetic diversity of H. inopinata confirms the relatively recent Baikal origin of the species in the Yenisei River, probably associated with an anthropogenic invasion.