Five species of psocids of the genus Amphigerontia Kolbe 1880, are recorded from the Rocky Mountains of the United States and Canada. Amphigerontia longicauda, n. sp., is described. Amphigerontia petiolata (Banks) is recorded from the Rocky Mountains for the first time. The holotype of Amphigerontia infernicola (Chapman) is re-examined and described in detail. New characters for the separation of females of Amphigerontia bijasciata (Latreille) and Amphigerontia montivaga (Chapman) resulted in many new records of the latter species, previously known in the Rocky Mountains from only a single locality. Species-level characters are reviewed and several new ones are added. A key to the species known from North America north of Mexico is included.
Originally published in Proceedings of the Entomological Society of Washington.