Echinomastus unguispinus subsp. minimus (A.B. Lau) U. Guzmán Echinomastus unguispinus subsp. minimus (A.B. Lau) U. Guzmán in Cactaceae Syst. Init. 16: 17. 2003 sec. Guzmán & al. 2003≡Echinomastus unguispinus var. minimus A.B. Lau in Kakteen And. Sukk. 34: 206. 1983 syn. sec. Guzmán & al. 2003