Echinocactus megapotamicus Osten in Anales Mus. Hist. Nat. Montevideo, ser. 2, 5(1): 72. 1941 Echinocactus megapotamicus Osten in Anales Mus. Hist. Nat. Montevideo, ser. 2, 5(1): 72. 1941Taxon for this nameEchinocactus megapotamicus Osten