Name and species boundaries
POWO accepts Aztekium valdezii as a separate species. Some older works, including the CITES list from 2016, treated it within A. ritteri. The database places its natural range in central Nuevo León. [2-WWW]
Characters described in the protologue
Plants are solitary or branch at the base. The globular, grey-green stem reaches up to 6 cm in height and diameter. In the type description, it has up to five main ribs with rounded edges. It lacks the secondary ribs characteristic of A. ritteri. Young areoles usually bear three papery, curved spines. Flowers are 1,5–2,5 cm in diameter, with whitish tepal bases and pink to purple distal portions. [Velazco Macías et al. 2013]
The diagnosis also gives importance to a seed with a well-developed strophiole, an appendage near the hilum and micropyle. The authors compared living specimens, herbarium material and seed surfaces under an electron microscope. They also found the small rib number in flowering plants. [Velazco Macías et al. 2013]
Siedlisko opisanej populacji
The protologue presents plants from steep canyons in the Sierra Madre Oriental, at 600–700 m elevation. Flowering was observed in late spring and early summer. The species was named in honour of its discoverer, Mario Alberto Valdéz Marroquín. [Velazco Macías et al. 2013]