Gymnocalycium schickendantzii

This is a nice looking broadly globular, somewhat flattened cactus

Origin and habitat: Córdoba, Northwest Argentina.
Flowers: The plant produces club-like purple buds on the older areoles on the side part of the stem, which develop into pinkish rose (rarely red) flowers, to 5 cm long and 7 cm in diameter. Often when full open the flowers remain almost tubular in shape and fail to open as broadly as other species do.
Fruits: Ovoid, green.

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