Nienna chukotka sp. nov. (Protura, Acerentomidae, Nipponentominae) from the Arctic region, with a key to species of the genus

A new species of Nienna was collected in the most northern part of the Palearctic, inside the Arctic Circle. In possessing seta Pc on tergite VII and sternites VI–VII and a very long foretarsal sensillum a, Nienna chukotka sp. nov. is more similar to Alaskaentomon species than to the other Nienna species distributed in southern Siberia and northern China. The new species differs from nearly all other members of Nipponentominae in possessing five anterior setae on tergite VII and in the presence of posterolateral pores on tergite I, as in members of Hesperentomon (Hesperentomidae). An identification key to Nienna species is provided.