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Thelocactus rinconensis ssp. rinconensis (Poselger) Britton & Rose, Cact. 4: 7 (1923).
Basionym: Echinocactus rinconensis Poselger, Allg. Gartenz. 23: 18 (1855).
Neotype: About 20 km northeast of Saltillo, 22 July 1972, Edward F. Anderson 3180 (US).
Synonyms: Echinocactus rinconadensis Schumann, Gesambt. Kakt. 433 (1898). ?Echinocactus lophothele Salm-Dyck, Allg. Gartenz. 18: 395 (1850). Thelocactus lophothele Br. & R., Bull. Torrey Bot. Club 49: 251 (1922). Echinocactus phymatothelos Poselger ex Ruempler, in Förster, Handb. Cact., ed. 2, 602 (1885). Thelocactus phymatothelos Br. & R. ('phymatothele'), Cact. 4: 8 (1923). Thelocactus rinconensis var. phymatothelos Glass & Foster, Cact. Succ. J. (US) 49: 246 (1977). Thelocactus rinconensis ssp. phymatothele (Poselger) Glass, Ident. Guide Threatened Cacti of Mexico 1: TH/RIN (1997). Thelocactus rinconensis ssp. phymatothelos (Poselger) Doweld nom. superfl., Sukkulenty 1: 30 (1999). Thelocactus rinconensis ssp. icamolensis Halda & Kupcak, Acta Mus. Richnov. sect. Nat. 7: 75 (2000).
Description
Stem single, depressed or globose, 6-8 cm tall, 12-20 cm wide. Ribs >20, distinct. Tubercles conical, angled. Areoles without glands. Central spines 3-4, 60-80 mm long, ochre to greyish, acicular to subulate. Radial spines absent. Flowers 40-70 mm wide, white or pink.
Distribution
Mexico, Coahuila and Nuevo León, occurring in matorral xerofilo on limestone hills.
Comments
The species is characterised by its glaucous, depressed stem, divided into about twenty ribs and the presence of central spines only. All entities share sunken or globose stems, divided into many (about twenty) narrow ribs, blue-green, rarely green. The number and strength of the spines and the colour of the flowers, instead, are variable. The type species, Thelocactus rinconensis ssp. rinconensis, has a glaucous body, depressed or globose, with areoles bearing 3-5 central spines of variable length, while radial spines are absent. The flowers are usually white, sometimes pinkish. Thelocactus phymatothelos is closely related to this taxon, and I believe it is a local form not deserving its own formal status. It can be distinguished because the stem is always depressed, the spines are shorter and slightly curved, and the flowers are pink.
- Icamolensis is a magenta flowering form occurring near Icamole, north-west of Monterrey, NL. It has been first reported by Glass and Foster who related it to ssp. nidulans. The body shape and spination, 3-4 central spines, rather relates it to ssp. rinconensis, from which it differs only for the flower colour. This difference is too weak to recognize it at a separate rank.
- Lophothele is a problem that is still to be solved. Salm-Dyck stated that it was collected by Potts in Chihuahua, but till now no plant matching the original description has been found in this state. It has usually been considered a form of rinconensis, but until it is rediscovered in the wild this epithet should not be used because of the uncertain status of this taxon.
- Phymatothelos, which occurs south of Saltillo, is not sufficiently distinct to deserve its own formal status. It can be distinguished because the stem is always strongly depressed, the spines are shorter and slightly curved, and the flowers are pink.
Thelocactus rinconensis
El Chiflon, Coahuila
Photo: J. Jauernig
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Thelocactus rinconensis
El Chiflon, Coahuila
Photo: J. Jauernig
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Thelocactus rinconensis
Rinconada, Coahuila
Photo: J. Chvastek
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Thelocactus rinconensis "phymatothelos"
Photo: A. Mosco
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home | © Alessandro Mosco 2004 | Last updated: 07-08-2005 | next
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