I am interested in the variability of this species and would like to see as many photos of plants which have clear habitat data.
I am aware of the following field collection numbers and assciated locations for Mammillaria marksiana:

H.O.397 Rancho de Padre.
L.621 Bucuberito, Sin, 400m - 600m.
L.635 Topia, Dur, 2000m.
MZ.782 Guadalupe, Sin
PN.135 Rio Zahuatenipa, Zaphuatenipa, Dur.
Rep.2173 Cerro de Fuso, Sin, 1400m.
Rep.2176 Parida, Sin, 1400m.
Rog.515 Topia, Dur
WK.386 Chiox to La reforma, Sin.
WK.419 North of La Soledad, Dur
WK.441 10km from Piede la Cusesta, Rio Sianori, Tamazula to Topia, Dur
WK.442 Tanizula, Rio Tamazula, Dur
WM.2470 Barranca de Topia, Dur

I have several of these collections, but would like to see more photos as corroboration that the plants are right.

If possible, I'd like to see any close-ups of the areoles an spines as well, obviously, as the plant itself.

And any information on the fruit would also be very helpful. Either post here, or pm me.

Thanks