Mammillaria difficilis Quehl in Monatsschr. Kakteenk. 18: 107. 1911
Mammillaria difficilis in Monatsschr. Kakteenk. 18: 107. 1911
is basionym for Coryphantha difficilis in Cactography: 3. 1926
Mammillaria difficilis in Monatsschr. Kakteenk. 18: 107. 1911
Taxon for this name