Cryptic refugee on the northern slope of the Greater Caucasian Ridge: Discovery of niphargus (Crustacea: Amphipoda: Niphargidae) in the North Ossetia–Alania, North Caucasus, separated from its relatives in the late Miocene

An endemic subterranean species of the genus Niphargus Schiödte, 1849 (Crustacea: Amphipoda: Niphargidae) belonging to the cave-dwelling “ carpathicus ” species group is discovered inside an abandoned mine in the Republic of North Ossetia–Alania, Russian Federation. This is the first record of the genus Niphargus from the central mountainous part of on the northern slope of the Greater Caucasian Ridge. Integrative taxonomy revealed that new species is closely related to European Niphargus ambulator than any of the Caucasian species, and has survived in cryptic refugia since the Miocene for more than 5.5Mya. It can also be assumed that the genus Niphargus was also previously distributed in the territory beyond the Caucasian Ridge to the North Caucasus and probably throughout the pre-Caucasian plain (Ciscaucasia). It is likely that most of the species from the Ciscaucasia became extinct presumably during the Pleistocene (Quaternary) glacial episodes or earlier, although we still expect the new relict species in cryptic refugia. Our study also suggests that subterranean species are narrowly localized and require strict protection and attention to their habitats, since the destruction of population leads to the loss of a unique genetic lineage and it is unlike to recover.