Abstract
This paper was prompted by the discovery, in the Tucson Mountains of Arizona, of a new psocid which apparently has as its closest relative a cave-inhabiting species of western Europe. The Arizona species represents a new genus which is a noteworthy addition to our Nearctic fauna, and, because of a lack of published revisionary work, a synopsis of the tribe to which the genus belongs has been prepared. One of the more interesting species of Psyllipsocini is Psyllipsocus ramburii Selys, which occurs in houses both in Europe and the United States, and which is dimorphic, both short-winged and long-winged individuals being found in the same colony. The European genus Prionoglaris Enderlein, which is closely related to the new Arizona genus, is unusual among pscoids in the lack of a lacinia in the adult, and a section devoted to mouth parts, especially those of these two genera, follows the main taxonomic part of the paper.