Cryophilic Isotomidae (Collembola) of the Northwestern Rocky Mountains, U.S.A.

Descriptions of Collembola from glaciers, snowfields and cold water seeps in Alaska, British Columbia, Alberta, Washington and Oregon are presented. Myopia alaskana Christiansen and Bellinger, and Desoria uniens Christiansen and Bellinger are redescribed. The following new species are described: Desoria albicornis sp. n., Desoria triangularis sp. n., Desoria ater sp. n., Desoria garibaldii sp. n., Desoria pilifrons sp. n., Desoria cryophila sp. n., Desoria rosea sp. n., Desoria olympica sp. n., Desoria capra sp. n. and Gnathisotoma spinolabris sp. n. One new genus, Mucronia gen. n. and its type species Mucronia enigmatica sp. n. are described from Alaska. The new genus possesses some characters of both the Isotomidae and Tomoceridae having a lobed post antennal organ and a mucro with two setae.