Gymnocalycium bruchii

This cactus is a mounding cactus. It has whitish short spines; they curve backwards towards the dark green body. It blooms flowers that go from pink to white.

Recommended temperature zone: USDA: 8-11
Frost tolerance: Hardy to 10° F (-12°C) or less
Minimum avg. temperature: 50°F (10°C)
Sun exposure: Full sun to light shade
Origin: Argentina (Córdoba)
Watering needs: Summer grower, water regularly in summer, keep rather dry in winter
Propagation: Seeds, offsets

Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz