Stem segments, spines and colour
Plants are low, up to about 15 cm tall in the regional description, with fibrous roots. Stem segments may be globular or ovoid. They are green in the wet season and may become reddish-purple in the dry season. Spines are often wavy, initially dark brown with a reddish base and becoming grey. Their variation also includes individuals with very weak armature. [Pauca-Tanco and Quipuscoa 2020]
Habitat and regional range
The revision described the species as endemic to Arequipa, growing around Uchumayo at 1920–2215 m within the Batolito de la Caldera. It occupies dry, open, sandy-stony substrates with little rainfall and sparse vegetation cover. Small annual species were listed among associated plants. [Pauca-Tanco and Quipuscoa 2020]
Flowers, fruits and seasonality
Yellow flowers develop at stem-segment tips, open during the day and turn orange as they wilt. In observed populations, flowering followed the rainy season in May–June, and fruiting occurred in July–October. Flowers were visited by hymenopterans, beetles and butterflies. The fruit is flattened, with a dry chamber and relatively weak spines. [Pauca-Tanco and Quipuscoa 2020]
Why the name has a long author citation
An earlier attempt to transfer Opuntia unguispina to Cumulopuntia did not meet the requirement for full citation of the basionym's place of publication. Pauca-Tanco and Quipuscoa corrected the combination and designated a neotype. The accepted author citation is therefore (Backeb.) F.Ritter ex A.Pauca & Quip. Older accounts also included these plants in C. sphaerica or C. leucophaea. [Pauca-Tanco and Quipuscoa 2020] [2-WWW]
Synonyms and names in the literature
Opuntia sphaerica var. unguispina · Opuntia unguispina · Sphaeropuntia unguispina · Tephrocactus sphaericus var. unguispinus · Tephrocactus unguispinus [2-WWW]