Tephrocactus nigrispinus

Stems and flowers

In the morphological comparison, the plant had slightly thickened roots, nearly cylindrical segments and needle-like spines. Leaves persisted longer than in species that shed them quickly. Segment connections were strong, helping retain a branched habit. [Las Peñas et al. 2019, appendix 1]

Red flowers develop on segments of a plant with a different outline from the typically globose T. geometricus or T. alexanderi. Fruit is fleshy and remains closed at maturity. The seed is surrounded by a hard covering with an uneven surface. [Las Peñas et al. 2019]

Sites and former treatment

The 2019 account included material from high elevations in Bolivia and northwestern Argentina, including Jujuy. The authors analysed its relationship with T. verschaffeltii. Both species shared relatively large, more persistent leaves, reddish flowers and fleshy fruit. [Las Peñas et al. 2019]

The name Maihueniopsis nigrispina is now a synonym of Tephrocactus nigrispinus. The current treatment retains species rank, with subspecies included in the atlas's taxonomic database. Results from older experiments concern the identified material without automatically extending them to every subspecies. [2-WWW] [Las Peñas et al. 2019]

Chromosome complement

The plants studied had 2n = 44. DNA content analysis also found endopolyploidy in somatic cells. Together with chloroplast data and seed structure, this result broadened the species' characterisation beyond traits visible on the outside of the stem. [Las Peñas et al. 2019, Table 2]