Accepted species and historical names
Plants of the World Online accepts nine Stenocactus species and the natural hybrid S. × irregularis. Current synonymy links S. pentacanthus with S. obvallatus, S. tetraxiphus with S. ochoterenanus, and S. lamellosus and S. dichroacanthus with S. crispatus. Older Echinofossulocactus names remain important for identifying material in the literature. [2-WWW]
Rib number and continuity
The study of populations from Bajío showed separate ranges of complete rib number in two identified parental species and a morphologically intermediate hybrid. S. coptonogonus had 12–14 complete ribs, and S. obvallatus material (S. pentacanthus in the paper) 30–53. S. × irregularis had 15–28 complete ribs and additional short sections, often ending without areoles. The ranges concern the populations analysed. [González-Zamora et al. 2023, p. 90–99, tabela V]
Young plants and microclimate
In S. coptonogonus seedlings, light, chlorophyll fluorescence, growth and hydration were compared beneath trees and in an open area. A separate experiment with two-year-old plants showed shorter survival in chambers that passively raised temperature and lowered relative humidity. Both designs characterise the sensitivity of early stages under different field conditions. [Pérez-Sánchez et al. 2015, Pérez-Sánchez et al., pp. 3–10. Aragón-Gastélum et al., pp. 94–97] [Aragón-Gastélum et al. 2017b, Pérez-Sánchez et al., pp. 3–10. Aragón-Gastélum et al., pp. 94–97]