Scope of the current treatment
Plants of the World Online accepts 13 species and the natural hybrid Thelocactus × mirandus. The genus includes T. setispinus, also known in the literature as Hamatocactus setispinus. Former subspecies of T. leucacanthus with the epithet schmollii and of T. hexaedrophorus with the epithet lloydii are included in their respective species in this treatment. [2-WWW]
Tubercles, areoles and fruits
The genus description presented by Sandoval-Ortega and colleagues includes spherical, flattened or short-cylindrical stems. Tubercles may be joined at the base into ribs. The areole at the tubercle tip may have a short groove on the side facing the stem apex. Flowers arise in its upper part, and the fruit retains perianth remnants and usually opens at the base. Some species have extrafloral nectaries. [Sandoval-Ortega et al. 2022, p. 47–48]
Climate and distinct microhabitats
Modelling of nine species showed differences in the importance of temperatures and seasonal rainfall. T. bicolor had the broadest estimated niche in the analysis, while T. buekii and T. conothelos were more clearly associated with precipitation in the driest quarter. The set comprises the species and records used by Mosco in 2019. The models describe the distribution of compatible conditions at a resolution of about one kilometre. [Mosco 2019, p. 3–6, 10–12]
Described in 2018, T. tepelmemensis grows in crevices and on ledges of steep limestone faces in northern Oaxaca. This southern site extended the genus's known range. The species was not included in the comparative analysis of nine niches. [Davis et al. 2018, Davis et al., pp. 116–121. Mosco, p. 3] [Mosco 2019, Davis et al., pp. 116–121. Mosco, p. 3]
Reproduction in the leucacanthus population studied
In a violet-flowering population of T. leucacanthus (subsp. schmollii in the paper) from La Estación in Querétaro, fruits and seeds formed after natural pollination and manual cross-pollination. Three treatments without foreign pollen produced no fruits. Brief, one-day anthesis and bee visits form the local reproductive system, described with the experiment's conditions and sample sizes. [Delgado-Ramírez et al. 2021, p. 793–800]
