This lovely flowering Mammillaria is not the cultivar 'Un Pico' (one long white spine per areole) but the usual form of the species, which has a lot more spines, often in colors other than white. I will be moving this image to the other entry in the database.

Mammillaria (Mammillaria spinosissima 'Un Pico')
Red-Headed Irishman (Mammillaria spinosissima)

Any questions, comments, or disagreement, just say the word.