Echinocactus simpsonii Engelm. in Trans. Acad. Sci. St. Louis 2: 197. 1863
Echinocactus simpsonii in Trans. Acad. Sci. St. Louis 2: 197. 1863
is basionym for Pediocactus simpsonii, Ill. Fl. N. U.S., ed. 2, 2: 570. 1913
is basionym for Pediocactus simpsonii var. simpsonii
is basionym for Mammillaria simpsonii in Zoë 3(4): 302. 1893
Echinocactus simpsonii in Trans. Acad. Sci. St. Louis 2: 197. 1863