The North American crab spiders are now comparatively well known taxonomically. This is particularly true of the species in the large genus Xysticus, which has been twice revised continentally by Gertsch (1939, 1953) and treated in more regional works by Buckle and Redner (1964), Schick (1965), and Turnbull, et al. (1965). It seems probable that any additional new forms that will be discovered will be from remote parts of the continent or in sibling relationship with known species. Several species have, however, been described only from one sex.The purpose of this paper is to describe a distinctive new species of Xysticus from the mountainous parts of Arizona. Its structure clearly places it in the locuples group of the apophysate division of the genus, and its range suggests it to be an inland endemic of the southwestern United States.