Thelocactus conothele var. aurantiacus Glass & Foster, Cact. Succ. J. (US) 44: 48 (1972).
Thelocactus conothele var. aurantiacus Glass & Foster var. nov.
A var. typica colore floris et colore spinarum differt.
Spinae centrales 4, porrectae vel vix recurvatae vel lateraliter curvatae, paullo complanatae, ca. 0.5 mm. latae, basi incrassatae et fusciores, juventute aurantiacae, demum griseo-brunneae, rigidae, paullo annulatae, inferiores 20-55 mm. longae, superiores 17-35 mm. longae, radii 17-23 rigidi, vitrei-albi, basi flavescentes, ca. 10-20 mm. longi.
BODY: solitary, ca. 11 cm. in diameter, ca. 10 cm. high, in habitat occasionally becoming somewhat columnar, pale green. Ribs completely divided into prominent tubercles.
TUBERCLES: arranged in 8 and 13 spirals, basally keeled, ca. 12 mm. across at base and 10 mm high.
AREOLES: woolly when young, ca. 3.5 mm. wide.
SPINES: central spines 4, porrect to slightly recurved to curving sideways, somewhat flattened, ca. .5 [sic] mm. wide, thickened and darker at base, orangish when young becoming grayish brown, stiff, slightly annulate; lowest 20 to 55 mm. long; upper 17 to 35 mm. long. Radial spines 17-23, stiff, glassy white, yellowish at base, ca. 10 to 20 mm. long.
FLOWERS: ca. 38 mm. long, scales on tube 3 mm. wide with finely fimbriate margin, pale yellowish with pale brownish green mid-stripe; outer perianth segments scalelike but elongated, with finely fimbriate margins; inner perianth segments ca. 5 mm. wide, rich brilliant yellow to orangey yellow in color, margins entire. Style 23 mm. long, style and 8 stigma lobes yellowish orange; anthers bright yellow.
SEED: very dark reddish purple to black, with finely tuberculate testa; ca. 1.5 mm. in diameter, with large hilum; somewhat irregular in shape with a constriction around the middle.
TYPE LOCALITY: rocky cliffs and hilltops just northwest of the town of Aramberri, Nuevo Leon, about 9 miles east of La Escondida.
HOLOTYPE: Glass & Foster #1383, collected February 12th, 1971, deposited at the Zürich Succulent Collection (Stadt Sukkulentensammlung) and isotypes were deposited at the Pomona College Herbarium and at the Herbarium of the Universidad Nacional Autonoma de Mexico.
Aside from its striking flower color, this variety differs from the type through its greater radial count, the color and shape of the central spines, and the isolated range in the valley of Aramberri.
We are naming this new variety for the remarkable color of the flowers, most unusual among the Mexican Cactaceae and more the color of Parodia aureispina than any Thelocactus! A certain variability in flower coloration is to be expected, particularly among the thelocacti, and we have seen Thelocactus conothele with purple, pink and pure white flowers, but true yellow is most unexpected and unusual. At the time the plants were collected, they were in flower.