1961. Peromyscus boylii ambiguus Alvarez, Univ. Kansas Publ. Mus. Nat. Hist., 14:118, December 29, type from Monterrey, Nuevo León.
Distribution in Tamaulipas.—Known only from the Sierra San Carlos.
Record of occurrence.—Specimens examined, 7 (UMMZ), all from La Vegonia, Sierra San Carlos.
Peromyscus boylii levipes Merriam
1898. Peromyscus levipes Merriam, Proc. Biol. Soc. Washington, 12:123, April 30, type from Mt. Malinche, 8400 ft., Tlaxcala.
1909. Peromyscus boylii levipes, Osgood, N. Amer. Fauna, 28:153, April 17.
Distribution in Tamaulipas.—Central and southern parts of state.
Weights of 19 males and 18 females from the Sierra Madre Oriental are, respectively, 25.2 (22-30) and 23.6 (20-29); weights of eight males and five females from the Sierra de Tamaulipas are 24.9 (22-32) and 29.6 (24-31).
Records of occurrence.—Specimens examined, 54: Sierra Madre Oriental, 8 mi. S, 6 mi. W Victoria, 4000 ft., 37; 5 mi. S, 3 mi. W Victoria, 1900 ft., 2; Ejido Eslabones, 10 mi. W, 2 mi. S Piedra, 1200 ft., 1; Sierra de Tamaulipas, 11 mi. W, 8 mi. S Piedra, 2000 ft., 13; 2 km. W El Carrizo, 1.
Additional records: Rancho del Cielo (Hooper, 1953:7); 3 mi. NW Acuña (ibid.); Rancho Viejo (Goodwin, 1954:12); Santa María (ibid.); Joya de Salas (ibid.).