Mammillaria formosa subsp. chionocephala (J.A. Purpus) D.R. Hunt, Mammillaria Postscripts 7: 3. 1998 sec. Hunt 2016
- =Mammillaria chionocephala J.A. Purpus in Monatsschr. Kakteenk. 16: 41. 1906 syn. sec. Hunt 2016
- =Neomammillaria chionocephala (J.A. Purpus) Britton & Rose, Cactaceae (Britton & Rose) 4: 101. 1923 syn. sec. ???
- =Mammillaria ritteriana Boed. in Monatsschr. Deutsch. Kakteen-Ges. 1: 173. 1929 syn. sec. Hunt 2016
- =Mammillaria caerulea R.T. Craig, Mammillaria Handb.: 306. 1945 syn. sec. Hunt 2016
- =Mammillaria ritteriana var. quadricentralis R.T. Craig, Mammillaria Handb.: 89. 1945 syn. sec. ???