Notocactus ottonis var. multiflorus Frič ex Buining in Succulenta (Netherlands) 1957: 105. 1957
Notocactus ottonis var. multiflorus in Succulenta (Netherlands) 1957: 105. 1957
is basionym for Notocactus linkii f. multiflorus, Kakteen Südamerika 1: 172. 1979
is basionym for Notocactus megapotamicus f. multiflorus in Repert. Pl. Succ. 44: 13. 1993