Mammillaria matudae Bravo Mammillaria matudae Bravo in Cact. Succ. J. Gr. Brit. 18: 83. 1956 sec. Hunt 2016=Mammillaria matudae var. serpentiformis Fittkau in Cact. Suc. Mex. 16: 42. 1971 syn. sec. Guzmán & al. 2003