Molecular Phylogeny of Gymnocalycium (Cactaceae): Assessment of Alternative Infrageneric Systems, a new Subgenus, and Trends in the Evolution of the Genus.
Pablo H. Demaio, Michael H. J. Barfuss, Roberto Kiesling, Walter Till, and Jorge O. Chiapella, American Journal of Botany 98(11): 1841-1854. 2011.
Abstract: Premise of the study: The South American genus Gymnocalycium (Cactoideae-Trichocereae) demonstrates how the sole use of morphological data in Cactaceae results in conflicts in assessing phylogeny, constructing a taxonomic system, and analyzing trends in the evolution of the genus. Methods: Molecular phylogenetic analysis was performed using parsimony and Bayesian methods on a 6195-bp data matrix of plastid DNA sequences (atpI-atpH , petL-psbE , trnK-matK , trnT-trnL-trnF) of 78 samples, including 52 species and infraspecific taxa representing all the subgenera of Gymnocalycium. We assessed morphological character evolution using likelihood methods to optimize characters on a Bayesian tree and to reconstruct possible ancestral states. Key results: The results of the phylogenetic study confirm the monophyly of the genus, while supporting overall the available infrageneric classification based on seed morphology. Analysis showed the subgenera Microsemineum and Macrosemineum to be polyphyletic and paraphyletic. Analysis of morphological characters showed a tendency toward reduction of stem size, reduction in quantity and hardiness of spines, increment of seed size, development of napiform roots, and change from juicy and colorful fruits to dry and green fruits. Conclusions: Gymnocalycium saglionis is the only species of Microsemineum and a new name is required to identify the clade including the remaining species of Microsemineum; we propose the name Scabrosemineum in agreement with seed morphology. Identifying morphological trends and environmental features allows for a better understanding of the events that might have influenced the diversification of the genus.

Gymnocalycium andreae subsp. pabloi Neuhuber subpec. nov.
Neuhuber, G. (2011) Gymnocalycium andreae (Boed.) Backeb. Geografische und morphologische Radiation einer scheinbar gut bekannten Pflanze. Gymnocalycium, 24(2): p. 981-990
Abstract: Reevaluation of the distribution and morphological data of Gymnocalycium andreae lead to the conclusion that var. grandiflorum should be merged with var. andreae. Typical G. andreae is restricted to the Sierra de Córdoba while the plants from the Sierra Chica represent an undiscribed taxon for which the name subsp. pabloi is proposed.
Typus: Argentinien, Provinz Córdoba, Sierra Chica, 32 km nach Ort El Manzano in Richtung La Cumbre, 1580 m s.m., leg. G. Neuhuber GN 99-1051/3728. 21.12.1999, (CORD, holo, WU, para).

Gymnocalycium esperanzae Repka & Kulhánek spec. nov.
Repka, R.; Kulhánek, T. (2011) Gymnocalycium esperanzae Repka et Kulhánek, a new species from La Rioja, Province Argentina. Schütziana, 2(3): p. 3-21
Abstract: A new species of the genus Gymnocalycium from the central-northern part of Argentina, G. esperanzae, is described with the morphological data. The species belongs to the subgenus Microsemineum and, according to the special structure of its seeds, is likely to be closely related to G. castellanosii, but markedly differs by less peripheral erect subulate dark spines, absence of central spines, the epidermis with a conspicuous grey bloom, significantly longer pericarpel, and by the spindle shape of fruit. The flowers have a longer pericarpel and fruit than its relatives (G. castellanosii s. l.). The new species grows on gravelly hills at the southern tip of the Sierra de Ulapes y Las Minas Mountains and can be indicated as stenoendemic to the Argentinean province of La Rioja.

Gymnocalycium oenanthemum var. montanum (Slaba) Slaba
Gymnocalycium oenanthemum Backeb. opét pod drobnohledem. - Kaktusy 47(2): 42 (2011).
Basionym: Gymnocalycium carminanthum var. montanum Slaba 1999.

Gymnocalycium oenanthemum var. tillianum (Rausch) Slaba
Gymnocalycium oenanthemum Backeb. opét pod drobnohledem. - Kaktusy 47(2): 44 (2011).
Basionym: Gymnocalycium tillianum Rausch 1970.