Acanthocereus fosterianus Holotype: Mexico, Tierra Colorada, along the Mexico City-Acapulco Highway or approx. 50 miles north of Acapulco, alt. 1500 ft, 1935, Foster, M. B. (MO: 054010) Lectotype: [illustration] fig. 27. “Flor de Peniocereus fosterianus var. nizandensis” in Sánchez-Mejorada in Cact. Suc. Mex. 19(2): 51. 1974 Lectotype: [illustration] fig. 28. “Flor de Peniocereus fosterianus var. multitepalum” in Sánchez-Mejorada in Cact. Suc. Mex. 19(2): 53. 1974