C. rarissima Ritt. (Kakt. Sudamer. 1980)

Habitat - Chañaral to north of Taltal.

Note: Taylor (1981) suggests this may be a form of C. hypogaea.

C. rubriflora Ritt. (Taxon 1963) Plant no.21, map 4. FR 211, KK 89, KK 658.

Body - 15 - 30 cm high, 6 - 12 cm across with ribs slightly notched; Areoles­4 - 8 mm across; Spines - brown, radials strongly curved, 2 - 4 cm long. 1 central (sometimes 2 - 3) 2.5 to 5 cm long; Flower - 3.5 - 5.5 cm long with petals 13 - 25 mm long, carmine with pale rose or pale saffron edges. Style pale saffron or pale carmine, stigma with 12 - 14 yellow or gold lobes. Tube 10 - 18 mm long. Nectar chamber 3 - 4 mm long, gland closed; Fruit - carmine with seed 1.4 mm long, 1 mm wide with brownish hilum; Roots - strong, long, thick with narrow neck; Habitat - south of Taltal on the coast in barren soil.

Note: Ritter considers this species to be similar to C. rupestris.

C. rupestris Ritt. (Taxon 1963)
Plant no.23, map 4. KK 195, KK 612, FR 528.

Body - firm, green to 40 cm high, 11 cm across, making loose clumps. 13 - 15 ribs, 10 - 12 mm high, somewhat flattened with raised tubercles; Areoles - round, pale brown 7 - 10 mm across; Spines - subulate, mostly slightly recurved, dark brown becoming grey. 6 - 8 radials, 1 - 2 cm long. 1 - 3 centrals, 2 - 4 cm long; Flower - 2.5 cm long with short acuminate petals, ca. 13 mm long, 5 - 7 mm wide, pale saffron. Stamens :t 15 mm long, pale saffron. Style 17 - 19 mm long, stigma with about 8 lobes; Fruit - green to red - green, 15 mm long, 7 mm wide with 6 - 12 reddish scales. Seed I mm long, 0.7 mm wide with white, oval hilum;
Habitat - rocky coastline near Cifuncho.

Note: Taylor (1981) suggests C. rubriflora could be a variety of C. rupestis. To be considered here would be C. hornilloensis and C. desertorum.