This form, known only from northwestern Argentina, has stiff yellowish rather than soft and bristly whitish spines and should not be confused with spiny races of forma lumbricoides. According to Schumann (1898: 635) they can be found sympatric in Tucuman. (Upper left drawing: Eaton, M.E.; watercolor in The Cactacea Vol 4 Pl 24, Fig 8, Smithsonian Institute website).

• Plant - stems terete, 3 to 4 mm. in diameter, somewhat angled and roughened in dried specimens.
• Areoles - close together, bearing wool and 8 to 10 appressed white bristles or spines.
• Fruit - not immersed, globose, 7 to 8 mm. in diameter, dark purple to nearly black, either naked or with 3 or 4 hairy areoles.
• Type locality - Catamarca, Argentina