Colour and Identification

[gehcole]

IMG_0672 (Small).JPG (100.96 KiB) Viewed 586 times

This beautiful Mammillaria (I think) started a redish colour on its points. I would very much appreciate 1. if someone could tell me what is happening and 2. positively identify the species.

[iann]

Mites. Or maybe mealies, but I can't see any.

Probably M. elongata, although they tend to form clumps quite quickly.