Distribution and current circumscription
The native range of Acanthocereus extends from southern Florida and the Caribbean, and from southern Texas to Venezuela. Most narrowly distributed species occur in Mexico and Central America. They mainly inhabit tropical forests with seasonal leaf fall. The widespread A. tetragonus occupies much of the geographic range of the genus. [2-WWW] [Vega et al. 2023, POWO 295870-2, 12.10.2026, Vega 2023 pp. 2]
A 2026 study recognized two additional species, A. crypticus and A. veronicae. The authors combined stem and reproductive characters with three chloroplast DNA regions. The sequence dataset included 14 samples of the genus. Both new entities occupied distinct positions in the analysis, consistent with their morphological characters. Their accounts on this website retain the basis provided by the original descriptions. [González-Zamora et al. 2026, pp. 1–4, 6, 10–11]
Stems change during development
In many species, juvenile stems have more ribs and more closely spaced areoles. Adult stems may retain conspicuous ribs or become almost cylindrical. In A. crypticus, the juvenile stem has three or four ribs, whereas the adult stem is cylindrical. In A. veronicae, three ribs occur in both stages. In A. lempirensis, rib number decreases from 6–10 in juvenile stems to 3–5 in developed stems. [González-Zamora et al. 2026, pp. 6, 11, Vega 2023 pp. 4] [Vega et al. 2023, pp. 6, 11, Vega 2023 pp. 4]
A plant description benefits from comparing juvenile growth with the mature stem, spine arrangement and floral structure. The new diagnoses used this combination of characters. Tuberous roots and a shrubby, upright or arching growth form are among the features documented in these species descriptions. Phenology and organ dimensions remain properties of individual species and populations. [González-Zamora et al. 2026, pp. 1, 6, 11, Vega 2023 pp. 2–4] [Vega et al. 2023, pp. 1, 6, 11, Vega 2023 pp. 2–4]