Crymostygidae, a new family of subterranean freshwater gammaridean amphipods (Crustacea) recorded from subarctic Europe

Crymostygidae, a new family of gammaridean amphipods (Crustacea), is described from Iceland. The family is based on a new species and genus, Crymostygius thingvallensis, found in spring inlets feeding Lake Thingvallavatn, south-west Iceland. This is the first report of a stygobiont freshwater amphipod from Iceland and the northern-most report of a stygobiont species in Europe. The species apparently survived Pliocene and Pleistocene glaciations in the groundwater of a porous lava and may have persisted in Iceland for several million years.