Mammillaria densispina ML312

Still quite a young plant, 3 years in my collection, acquired from John Pilbeam.

Densispina with somewhat different spination colour, this could be because it is still a young plant.

Yes, I have another densispina that has much yellower spination, and of course darker as well in buxbaumeriana. This is somewhere in between, and is very similar to the photo in Pilbeam of a plant he found in Jalisco. But ML312 comes from La Cienega - Terrero del Refigio, Aguascalientes.
I soppose the fact that there is such variability of spine colour is why buxbaumeriana was lumped into densipsina, although the flower is a much clearer yellow with no hint of reddish stripe on the outer petals.