A new subgenus, Zosteridionis, is proposed for five species, including the type species Hexidionis deserti, n. sp., type locality, 3 mi. SE Needles, San Bernardino Co., California, off Dipodomys m. merriami. The subgenus Hexidionis consists of five species including, Hexidionis macropus, n. sp., from La Burrera. Baja California Sur, Mexico, off Peromyscus eremicus.