Mammillaria sp.?

[ToadGoGreen24]

Hi gang!

Got a cactus in a keyring back in '07. Smaller than my little fingernail, he was.

He looked very much like this (Thelocactus)

George6.jpg (59.13 KiB) Viewed 1957 times

Repotted him a couple of times, he flowered once in 2010 (one flower out the top).

Now he's a beast and flowering again. What is he?

George5.jpg (72.55 KiB) Viewed 1957 times

George1.jpg (91.29 KiB) Viewed 1957 times

George3.jpg (72.23 KiB) Viewed 1957 times

I think I'm leaning towards Mammillaria because of his flowers.
M. polyedra (is my best guess)
M. sartorii
M. tepexicensis
M. winterae

Any help is greatly appreciated.

That woolly stuff forms tight twists that then become the flowerbuds. Awesome...

[Tom in Tucson]

Based on my limited experience with growing a few milky types of this genus, my first impression was that it could be a M. magnimamma. The guess of it being a M. sartorii seems possible, though less likely.

[ToadGoGreen24]

That's a great shout.
Thanks very much!
Mammillaria magnimamma. That is TOO GOOD a name...