Gymnocalycium, Taschenb. Cactuslieb. 2: 124. 1844 sec. Demaio & al. (2011)
- Type: Gymnocalycium gibbosum
Found as monophyletic at first by Ritz & al. (2007), then studied in more detail and confirmed as monophyletic by Meregalli & al. (2010). Demaio & al. (2011) conducted the most detailed phylogenetic study by sampling almost the whole genus and again confirmed the monophyly of Gymnocalycium with maximal support. Recent illustrated synopsis by Charles (2009). Published as "Gymnocalicium".