Pelecyphora aselliformis

Accepted name and distribution

POWO accepts Pelecyphora aselliformis C.Ehrenb., published in 1843. Its synonymy includes Ariocarpus aselliformis, Mammillaria aselliformis and var. concolor. The 2022 systematic paper also records Anhalonium aselliforme. The current POWO record gives a natural range in northeastern Mexico, extending towards Jalisco. [2-WWW] [Sánchez et al. 2022, POWO, as of 11 October 2026. Sánchez et al., p. 131]

The introduction to the 2002 micropropagation experiment describes plants from several sites in San Luis Potosí, growing at soil level with a flattened habit. The authors reported solitary or clumping stems 1–3 cm high and 2–5 cm in diameter. This is the characterisation used in the paper's introduction. The broader modern range given by POWO reflects the current species circumscription. [Pérez-Molphe-Balch and Dávila-Figueroa 2002, Pérez-Molphe-Balch and Dávila-Figueroa, p. 73] [2-WWW]

Tubercles resembling small woodlice

Elongated areoles with densely arranged spines give the stem surface its distinctive appearance. The comparison with woodlice refers to the outline of this spiny covering. In an adult plant it helps distinguish the species from P. strobiliformis, whose triangular tubercles form a cone-like body. Both structural forms were described in Kew's botanical account of the classical two-species circumscription of the genus. [Sajeva et al. 2012, p. 27]

A short, vestigial groove occurs on the dorsal surface of the tubercle. The 2022 paper presents it as a structure homologous to the longer grooves of plants from the former Escobaria. The reduction of this character visible on the stem occurs alongside membership in the same evolutionary lineage. In this study, P. aselliformis was placed in a group with P. strobiliformis, P. chihuahuensis and P. tuberculosa. [Sánchez et al. 2022, p. 119, 123–125, ryc. 1–3]

Perianth and seed surface

The outer tepals may have entire or finely fringed margins. In P. strobiliformis, the margin was described as consistently fringed. Margin variation in P. aselliformis is one of the exceptions considered when characterising the broad genus. Comparing flowers with tubercles and seeds provides a fuller set of characters than a single surface detail. [Sánchez et al. 2022, p. 124]

The pitted relief of the seed coat results from the thin outer cell wall collapsing across its entire surface. In classical Pelecyphora, the development of this wall differs from that of many former Escobaria, where mainly the central part was thin. The way the relief forms explains why closely related plants may have pitted seed coats with different cell shapes and depression sizes. [Sánchez et al. 2022, p. 124]

Shoots developing from areoles

In the 2002 experiment, seedling fragments produced shoots from existing areoles. On MS medium with 30 g/L sucrose and 8.8 µM benzyladenine, apical fragments produced a mean of 13.70 ± 1.37 shoots after 60 days. After three cycles totalling 180 days, 128.07 ± 9.16 shoots were obtained per initial explant. These values are means with standard errors for this experimental treatment. [Pérez-Molphe-Balch and Dávila-Figueroa 2002, p. 74, tab. 1]

Cultures were maintained at 25 ± 2°C, with 16 hours of light per day and a photosynthetic photon flux of 54 µmol m⁻² s⁻¹. Shoots were elongated before rooting. In a separate stage assessed after six weeks, 89% of shoots of the species developed roots reaching at least 15 mm. The rooting result was reported collectively for the auxin treatments used. [Pérez-Molphe-Balch and Dávila-Figueroa 2002, p. 74–77]

Micrografting onto prickly pear

Badalamenti and colleagues took 5 mm apical scions and 3 mm subapical segments containing at least one areole from seedlings. These were grafted onto freshly cut fragments of Opuntia ficus-indica. The rootstocks were 10 mm long and initially rootless. Micrografting was carried out on MS medium without added growth regulators, at 25 ± 1°C and with a 16-hour day. [Badalamenti et al. 2016, pp. 2–3]

In the sample of 30 apical scions, graft success was 97 ± 0.7%, compared with 81 ± 1.2% for 270 subapical segments. The subapical segments produced a mean of 2.7 ± 0.3 new shoots, compared with 1.0 from the apices. After transfer out of culture, 85 ± 0.8% of plants survived at two months. This last result was presented collectively for the micrografts obtained. [Badalamenti et al. 2016, pp. 3–4, Table 1]

Controlled environment for young plants

The in vitro experiments concern young plants growing in a sterile, controlled environment. Sucrose in the medium, a long photoperiod and humidity during acclimatisation are parts of the laboratory procedure. Their roles can be traced in the micropropagation article. Shoots with their own roots and plants left on a rootstock are two different types of material obtained in the studies described. [Pérez-Molphe-Balch and Dávila-Figueroa 2002, culture and acclimatisation conditions described in both papers] [Badalamenti et al. 2016, culture and acclimatisation conditions described in both papers]

Related articles

Materials from the author's archive

The species also appears in Konrad Szychowski's private material archive. [Hils 1989, file p. 5] [Biuletyn PTMK, Oddział we Wrocławiu 1989, file p. 10] [Rodríguez Ortega and Franco 2001, file p. 6]