Notocactus arechavaletae var. horstii F.Ritter, Kakteen Südamerika 1: 166. 1979
Notocactus arechavaletae var. horstii, Kakteen Südamerika 1: 166. 1979
is basionym for Parodia ottonis subsp. horstii in Cactaceae Consensus Init. 6: 12. 1998
is basionym for Notocactus spegazzinii var. horstii in Kaktusy (Brno) 46: 102. 2010
is basionym for Notocactus ottonis subsp. horstii in Sukkulenty 3: 55. 2000
is basionym for Peronocactus ottonis subsp. horstii in Sukkulenty 2(2): 21. 1999