Synonyms: Notocactus arachnitis; Notocactus arachnitis f. darilhoensis; Notocactus arachnitis f. minor; Notocactus arachnitis minor; Notocactus arachnitis var. minor; Notocactus crassigibbus (homotypic); Notocactus meonacanthus; Notocactus uebelmannianus; Notocactus uebelmannianus f. flaviflorus; Notocactus uebelmannianus f. gilviflorus; Notocactus uebelmannianus f. nilsonii; Notocactus uebelmannianus pleiocephalus; Notocactus uebelmannianus var. nilsonii; Notocactus uebelmannianus var. pleiocephalus; Parodia meonacantha; Parodia werneri; Parodia werneri pleicephala; Parodia werneri pleiocephala; Parodia werneri werneri; Ritterocactus crassigibbus (homotypic); Ritterocactus meonacanthus; Ritterocactus uebelmannianus; Ritterocactus uebelmannianus pleiocephalus