T. phymatothelos can be distinguished from other form  of the T. rinconensis complex because the stem is always strongly depressed and glaucous , the spines are shorter and slightly curved, and the flowers are more or less clear pink.

Synonyms:

• Echinocactus phymatothelos Poselger ex Ruempler, in Förster, Handb. Cact., ed. 2, 602 (1885).
  Thelocactus rinconensis (Poselg.) Britton & Rose [detailed view
• 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).

Cultivation: Easy to cultivate. Water moderately from Spring to Autumn. In Winter, keep dry. Sun Exposure: Full sun to light shade
Reproduction: Nearly always from seed, since the plant rarely produces plantlets.

Thelocactus phymatothelos is now considered a synonym of T. rinconensis, along with T. lophothele, T. nidulans, and others. It is not sufficiently distinct to deserve its own formal status.

Photo of conspecific taxa, varieties, forms and cultivars of Thelocactus rinconensis:

• T. rinconensis

• T. rinconensis ssp. freudenbergeri

• Thelocactus rinconensis var. phymatothelos