Ritterocereus pruinosus (Otto) Backeb. in Cact. Succ. J. (Los Angeles) 23(4): 121. 1951 Ritterocereus pruinosus (Otto) Backeb. in Cact. Succ. J. (Los Angeles) 23(4): 121. 1951is new combination for Echinocactus pruinosus Otto ex Pfeiff., Enum. Diagn. Cact.: 54. 1837Taxon for this nameRitterocereus pruinosus (Otto) Backeb.