Mammillaria hahniana Werderm.

Solitary or clustering, body globular or eventually elongate, to 10 cm wide, with milky sap. Tubercles obscure, conical. Axils with white wool and 20-30 bristles to 4 cm. Central spines 1-5, 4-8 mm long, white, tips reddish, eventually falling. Radial spines 20-30, 5-15 mm long, white, hairlike. Flowers carmine pink, 1.5-2 cm long and wide. Fruit reddish-purple.

C Mexico

Source: Thompson, A, ; Forbes, S.; Spencer, R. (1997). Cactaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.

kingdom Plantae
phylum   Tracheophyta
class    Magnoliopsida
superorder     Caryophyllanae
order      Caryophyllales
family       Cactaceae
genus        Mammillaria Haw.