In this study we report two new stygomorphic amphipods, Palearcticarellus hyperboreus sp. nov. and Pseudocrangonyx elgygytgynicus sp. nov., from Lake El’gygytgyn in north-eastern Siberia. Molecular phylogenetic analyses confirm their affinity to Crangonyctidae and Pseudocrangonyctidae, respectively, and reveal that speciation preceded Pleistocene glaciations. Although adapted to subterranean life, these species are found exclusively in surface waters, highlighting Lake El’gygytgyn as a high latitude refugium for ancient pre-glacial fauna and expanding the known distribution of stygomorphic amphipods. (Image credit: Denis Copilaş-Ciocianu and Dmitry Sidorov.)