A new family of heterostigmatic mites, Athyreacaridae, is described on the basis of a group of 9 species whose adult females are phoretic on adult geotrupine scarab beetles of the genus Neoathyreus Howden and Martinez from Mexico, Central America, and South America. Athyreacarus new genus is described as the type genus of the family, based on material representing the type species, A. pleiotretus new species, and 3 undescribed species; it is differentiated from a group of 5 other undescribed species which are thought to represent another, undescribed, genus. These mites evidently live symbiotically in the burrows of their beetle host; however, their feeding habits and life cycle are unknown.