Hypogastrura arnei (Collembola, Hypogastruridae), a remarkable new species from the Appalachians (USA)

Hypogastrura arnei sp. nov. is described from the USA. This species has a unique combination of morphological characters: an oval and slightly flattened body, a coarse tegumental granulation, a plurichaetotic dorsal chaetotaxy, antennal segment IV with 4-6 lateral sensilla and 1 dorsal cylindrical sensillum, a moderately modified furca and minute anal spines without papilla. The new species is closely related to H. iwamurai Yosii, 1960, H. reticulata Börner, 1909 and several members of the nivicola (= socialis), packardi (= sahlbergi) and crassaegranulata groups sensu Christiansen & Bellinger (1980), Babenko et al. (1994) and Skarżyński (2009).