First reports on the genetic diversity and phylogenetic relationships of bathynellids (Malacostraca: Bathynellidae) from Lake Baikal

Abstract

Within the fauna of Lake Baikal, two species of bathynellids are known: Bathynella baicalensis Bazikalova, 1954 and Baicalobathynella magna (Bazikalova, 1954), both originally described from the southern basin of the lake. The authors’ findings indicate that bathynellids are prevalent across all three basins of the lake, occuring on habitats such as methane seeps, mud volcanoes and hydrothermal vents. A comprehensive analysis of the COI (mtDNA) and 18S rRNA (nuclear DNA) gene fragments from bathynellids collected at tectonic fault sites in the northern basin of the lake revealed the absence of any representatives of the genus Bathynella Vejdovsky, 1882 among them. Instead, individuals identified as Baicalobathynella cf. magna comprise two genetic lineages at the species level, which diverged from a common ancestor approximately 7 Ma. The genus Altainella Camacho, 2020, whose representatives inhabit the interstitial hyporheic zone of the Onon river in Mongolia and Aktru mountain river of Altai, is designated as the closest relative of the Baikal bathynellids studied.