Conquest of the deep, old and cold: an exceptional limpet radiation in Lake Baikal.

Lake Baikal is the deepest, oldest and most speciose ancient lake in the world. The lake is characterized by high levels of molluscan species richness and endemicity, including the limpet family Acroloxidae with 25 endemic species. Members of this group generally inhabit the littoral zone, but have been recently found in the abyssal zone at hydrothermal vents and oil-seeps. Here, we use mitochondrial and nuclear data to provide a first molecular phylogeny of the Lake Baikal limpet radiation, and to date the beginning of intra-lacustrine diversification. Divergence time estimates suggest a considerably younger age for the species flock compared with lake age estimates, and the beginning of extensive diversification is possibly related to rapid deepening and cooling during rifting. Phylogenetic relationships and divergence time estimates do not clearly indicate when exactly the abyssal was colonized but suggest a timeframe coincident with the formation of the abyssal in the northern basin (Middle to Late Pleistocene).

Terrestrial predatory leeches of the genus Orobdella (Hirudinea: Erpobdelliformes: Orobdellidae) endemic to the Southern Russian Far East: a new species of the genus from Primorsky Krai, Russia.

A quadrannulate species, Orobdella ganini sp. nov., is described from the Lazovsky Nature Reserve in Primorsky Krai, the Southern Russian Far East, Russia. Morphological features of O. ghilarovi Nakano & Prozorova, 2019 from the reserve are also provided leading to an amendment of the species diagnosis. Maximum likelihood and Bayesian inference phylogenetic analyses, which were performed using nuclear 18S rRNA, 28S rRNA, and histone H3, and mitochondrial cytochrome c oxidase subunit I, tRNACys, tRNAMet, 12S rRNA, tRNAVal, 16S rRNA, tRNALeu and NADH dehydrogenase subunit 1 markers, show that O. ganini sp. nov., O. ghilarovi and two species endemic to Hokkaido, Japan form a clade, with the new species sister to a lineage composed of the two Japanese species. A partial cytochrome c oxidase subunit I sequence obtained from a cocoon found in the Lazovsky Nature Reserve reveals that Orobdella leeches deposit cocoons somewhat similar to those deposited by terrestrial blood-sucking leeches of Haemadipsidae.