Autor: Pfeiffer
• ETYMOLOGY
“Naked calyx” making reference to the hairless and spineless floral tube of the genus.
• DESCRIPTION
A genus of usually solitary low-growing plants, sometimes clustering, globose to shortly cylindrical, with the apex depressed. Ribs rounded, sometimes spiralled, often tuberculate, sometimes chinned. Areoles rather large, spines variable, never hooked.
Flowers diurnal, subapical, funnel-shaped to bell-shaped, white, creamy-white, yellow, pink, red, tube with large scales and hyaline margins, areoles naked, pollinated by bees: Andrenidae (Acamptopoeum prinii, Anthrenoides micans, Arhysosage cactorum, Callynochium petuniae, Psaenythia annulata, P. superba), Anthophoridae (Ancyloscelis fiebrigii, Lanthanomelissa completa, Ceratina asunciana, C. hyemalis, C. rupestris, C. volitans, Ptilothrix fructifera),
Apidae (Plebeia emerina, P. wittmannii), Colletidae (Cephalocolletes rugata), Halictidae (Augochlora semiramis, Augochloropsis euterpe, Dialictus sp.) Megachilidae (Lithurgus rufiventris) (Schlindwein & Wittmann 1995, 1997). Fruits globose to elongated, dry or fleshy, dehiscent laterally, bursting or deliquescent, floral remains persistent. Extremely variable seeds (a basis for the classification of the genus). Dispersion of seeds, and according to their structure, provided by ants (myrmecochory), also by rainwater (hydrochory).
• HABITAT
The genus Gymnocalycium has a very wide geographical range and habitats are very diverse. It grows in mountains, on rocky hillsides preferably in the shade among grasses, under shrubs, often at ground level, cryptic, on gritty, rocky, clayey or sandy soils, among granitic rocks, in areas of erosion, in cracks or on fallen rocks, on rocky outcrops among mosses and lichens, in pockets of humus mixed with quartz gravels, with plant debris, more rarely in full sun, in grasslands, near salt lakes or fossil dunes (Gymnocalycium marsoneri subsp. megatae), on salty soils (G. ragonesei)
or even swampy (6. schroederianum). It is found in the mountains of southern Bolivia and northern Argentina, in the warm and wet plains of southern Brazil, dry savannas of Paraguay (Chaco), and southern Argentina in rather mountainous and cold regions (where frosts prevail), from 50 m (G. schroederianum) up to 3000 m in altitude (6. spegazzinii).
• DISTRIBUTION
Argentina (Buenos-Aires, Catamarca, Chubut, Cordoba, Corrientes, Entre Rios, Jujuy, La Pampa, La Rioja, Mendoza, Misiones, Neuquen, Rio Negro, Salta, San Juan, San Luis, Santa Fe, Santiago del Estero, Tucuman), Bolivia (Chuquisaca, Cochabamba, Potosi, Santa Cruz, Tarija), Brazil (Mato Grosso do Sul, Rio Grande do Sul), Paraguay (Alto Paraguay, Boqueron, Concepcion, Cordillera, Paraguari, Presidente Hayes), Uruguay (Durazno, Rio Negro).
Currently 60 recognised species + 18 subspecies :
– Gymnocalycium albiareolatum Rausch 1985
– Gymnocalycium amerhauseri* H.Till 1994
– Gymnocalycium andreae* (Boed.) Backeb. 1935
– Gymnocalycium angelae Meregalli 1998
– Gymnocalycium anisitsii* (K.Schum.) Britton & Rose 1922
– Gymnocalycium anisitsii subsp. damsii* (K.Schumann) G.Charles 2005
– Gymnocalycium baldianum* (Speg.) Speg. 1925
– Gymnocalycium bayrianum* H.Till 1987
– Gymnocalycium berchtii G.J.A.Neuhuber 1997
– Gymnocalycium bodenbenderianum* (Hosseus ex A.Berger) A.W.Hill 1933
– Gymnocalycium bruchii* (Speg.) Hosseus 1926
– Gymnocalycium buenekeri Swales 1978
– Gymnocalycium calochlorum* (Boed.) Y.ito 1952
– Gymnocalycium capillaense* (Schick) Hosseus 1926
– Gymnocalycium cardenasianum F.Ritter 1964
– Gymnocalycium carolinense (Neuhuber) Neuhuber 1994
– Gymnocalycium castellanosii* Backeb. 1936
– Gymnocalycium castellanosii subsp. ferocius* (H.Till & Amerhauser) G.Charles 2005
– Gymnocalycium chacoense* Amerhauser 1999
– Gymnocalycium chiquitanum Cardenas 1963
– Gymnocalycium denudatum* (Link & Otto) Pfeiff. ex Mittler 1844
– Gymnocalycium erinaceum* J.G.Lambert 1985
– Gymnocalycium eurypleurum* F.Ritter 1979
– Gymnocalycium fischeri* Halda, Kupcak, Lukasik & Sladkovsky 2002
– Gymnocalycium gibbosum* (Haw.) Pfeiff. ex Mittler 1844
– Gymnocalycium gibbosum subsp. borthii (Koop ex H.Till) G.Charles 2005
– Gymnocalycium glaucum* F.Ritter 1963
– Gymnocalycium glaucum subsp. ferrari* (Rausch) G.Charles 2005
– Gymnocalycium horridispinum* G.Frank ex H.Till 1987
– Gymnocalycium horridispinum subsp. achirasense (H.Till & Schatzl ex H.Till) G.Charles 2009
– Gymnocalycium horstii* Burning 1970
– Gymnocalycium hossei* F.Haage 1927
– Gymnocalycium hyptiacanthum* (Lemaire) Britton & Rose 1922
– Gymnocalycium hyptiacanthum subsp. netrelianum* (Monville ex Labouret) Meregalli 2008
– Gymnocalycium hyptiacanthum subsp. uruguayense* (Arechavaleta) Meregalli 2008
– Gymnocalycium intertextum Backeb. ex H.Till 1987
– Gymnocalycium kieslingii* O. Ferra ri 1985
– Gymnocalycium kroenleinii Kiesling, Rausch & Ferrari 2000
– Gymnocalycium marsoneri* Fric ex Y.lto 1957
– Gymnocalycium marsoneri subsp. matoense (Burning & Brederoo) P.J.Braun & Esteves 1995
– Gymnocalycium marsoneri subsp. megatae* (Y.lto) G.Charles 2009
– Gymnocalycium mesopotamicum* R.Kiesling 1980
– Gymnocalycium mihanovichii* (Fric ex Gurke) Britton & Rose 1922
– Gymnocalycium monvillei* (Lem.) Britton & Rose 1922
– Gymnocalycium mostii* (Gurke) Britton & Rose 1918
– Gymnocalycium mostii subsp. valnicekianum* (Jajo) Meregalli & Charles 2008
– Gymnocalycium neuhuberi H.Till & W.Till 1992
– Gymnocalycium nigriareolatum Backeb. 1934
– Gymnocalycium ochoterenae Backeb. 1936
– Gymnocalycium ochoterenae subsp. vatteri (Burning) Papsch 1993
– Gymnocalycium oenanthemum* Backeb. 1934 (= G. corminanthum, G. tillianum)
– Gymnocalycium paediophilum F.Ritter ex Schutz 1977
– Gymnocalycium paraguayense* (K.Schum.) Hosseus 1939
– Gymnocalycium pflanzii* (Vaupel) Werderm. 1935
– Gymnocalycium pflanzii subsp. argentinense* H.Till & w.Till 1988
– Gymnocalycium pflanzii subsp. zegarrae* (Cardenas) G.Charles 2005
– Gymnocalycium prochazkianum Sorma 1999
– Gymnocalycium pugionacanthum* Backeb. ex H.Till 1987
– Gymnocalycium quehlianum* (F.Haage ex Quehl) Vaupel ex Hosseus 1926
– Gymnocalycium ragonesei A.Cast. 1950
– Gymnocalycium reductum* (Link) Pfeiff. ex Mittler 1844
– Gymnocalycium reductum subsp. leeanum* (Hooker) Papsch 2000
– Gymnocalycium rhodantherum* (Boed.) Backeb. 1936 (= G. guanchinense)
– Gymnocalycium ritterianum* Rausch 1972
– Gymnocalycium robustum* Ferrari & Metzing 2002
– Gymnocalycium saglionis* (Cels) Britton & Rose 1922
– Gymnocalycium schickendantzii* (F.A.C.Weber) Britton & Rose 1922
– Gymnocalycium schickendantzii subsp. delaetii (K.Schumann) G.Charles 2005
– Gymnocalycium schroederianum Osten 1941
– Gymnocalycium schroederianum subsp. bayense Kiesling 1987
– Gymnocalycium schroederianum subsp. boessii Kiesling, Marchesi & Ferrari 2002
– Gymnocalycium schuetzianum H.Till & Schatzl 1981
– Gymnocalycium spegazzinii Britton & Rose 1922
– Gymnocalycium stenopleurum* F.Ritter 1979 (ex G. Friedrichii)
– Gymnocalycium striglianum* Jeggle ex H.Till 1987
– Gymnocalycium stuckertii (Spegazzini) Britton & Rose 1905
– Gymnocalycium taningaense Piltz 1990
– Gymnocalycium uebelmannianum* Rausch 1972
References: "TAXONOMY of the CACTACEAE" - ISBN 978-84-617-3723-9 (Vol. 1)