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Thelocactus conothelos ssp. conothelos (Regel & Klein) Backeb. & F. Knuth, Kaktus-ABC, 385 (1935).
Basionym: Echinocactus conothelos Reg. & Klein, Ind. Sem. Hort. Petrop. 48 (1860).
Neotype: 1 mile southwest of La Perdida, Tamaulipas, Mexico, 22 January 1961, Edward F. Anderson1725 (POM).
Synonyms: Gymnocactus conothelos Backeb., Die Cactaceae V: 2859 (1961). Torreycactus conothele (Regel & Klein) Doweld, Sukkulenty 1: 19 (1998). Thelocactus conothele var. albiflorus Kladiwa & Fittkau nom. nud., in Krainz, Die Kakteen, C VIII b, 1 IV (1975). Echinocactus smithii Muehlenpf. nom. rej. prop., Allg. Gartenzeitung 14: 370 (1846). Echinocactus saussieri Weber, Dict. Hort. Bois, 468 (1896). Thelocactus saussieri Berger, Kakteen, 257 (1929). Gymnocactus saussieri Backeb., Cact. Succ. J. (US) 23: 151 (1951).
Description
Stem single, globose, 6-24-(45) cm tall, 7-18 cm wide. Ribs indistinct. Tubercles conical. Areoles with glands. Central spines 4, 13-90 mm long, ochre to greyish, straight, acicular. Radial spines 7-20, 8-12 mm long, ochre to greyish, straight, acicular. Flowers 45-60 mm wide, white to magenta.
Distribution
Mexico, Nuevo León, San Luis Potosí and Tamaulipas, occurring in matorral xerofilo on limestone hills.
Comments
Thelocactus conothelos and its subspecies (argenteus, aurantiacus, flavus and garciae) are the most different from the other Thelocacti, both for flower morphology (in these species the primary filaments are inserted 4-5 mm above the base of the nectar chamber) and for seed micro-morphology (seed testa cells are conical and the surface of the cuticle is smooth). The seed-coat micro-morphology led Doweld to propose a new genus, Torreycactus, for them, placing it in a distinct phylogenetic line together with Kadenicarpus and Bravocactus, both having seeds with a smooth cuticle. My opinion is that this single trait is not sufficient to segregate conothelos from Thelocactus, especially when all the other characters are congruent with those of the other Thelocactus species.
Thelocactus conothelos is the most widespread taxon of this complex, distributed in many localities of the states of Nuevo León, San Luis Potosí and Tamaulipas. The forms with depressed stem growing around Matehuala are known by the name saussieri, while the typical form, with a more elongate stem, is found in Tamaulipas. Flowers are typically magenta, though I know about a population near Matehuala, where white and magenta flowered plants grow together.
- Saussieri is a name referable to the plants with depressed globose stem growing around Matehuala, in Nuevo León and San Luis Potosí. There are no other differences from the type.
- Smithii is a name that for many years was used to identify a spiny form of Rapicactus beguinii. The original description refers to a completely different plant which is identifiable as Thelocactus conothelos.
Thelocactus conothelos
Dr Arroyo, Nuevo León
Photo: A. Mosco
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Thelocactus conothelos
Dr Arroyo, Nuevo León
Photo: A. Mosco
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Thelocactus conothelos
Jarillas, Nuevo León
Photo: A. Mosco
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Thelocactus conothelos
Miquihuana, Tamaulipas
Photo: A. Mosco
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