Structure and identification
The stem is spherical or slightly flattened, with large tubercles and a densely woolly apex. The monograph describes a short taproot with fibrous branches and stolon production. The three central spines are strong, dark in new growth and curved towards the stem. None dominates as a straight spine projecting forwards. The lower one is longer than the two lateral ones. Flowers are large and cream-yellow. [Dicht and Lüthy 2005, p. 72, 145]
Habitat and variation
The described type locality is in Zacatecas. The monograph associates the plant with clay substrate on plains and gentle slopes, beneath small shrubs and other xerophytes. The 2016 morphological analysis also recognised the arrangement of three inward-curving central spines as a characteristic diagnostic feature. [Dicht and Lüthy 2005, p. 72, 145; p. 39] [Vázquez-Benítez et al. 2016, p. 72, 145; p. 39]
Related articles
Materials from the author's archive
The species also appears in Konrad Szychowski's private material archive. [Neciu b.d., file p. 1]