Coryphantha clavata (Scheidw.) Backeb. Coryphantha clavata (Scheidw.) Backeb. in Cactaceae (Berlin) 1941: 61. 1942 sec. Guzmán & al. 2003≡Mammillaria clavata Scheidw. in Bull. Acad. Roy. Sci. Bruxelles 5: 494. 1838 syn. sec. Guzmán & al. 2003