Please can anyone ID this plant from El Pantano, San Luis Potosi?

Please are there any ideas of an ID for this plant, from El Pantano (San Luis Potosi)? It has a collection number PJ274 from Pavol Jesensky, Slovakia, but maybe it is already recognised with another name.

Seller's Picture:



My side view Picture:



My overhead view Picture:

Is it certain to be a Mammillaria? Could it be a Thelocactus or Coryphantha? Could it be a previously undescribed species?

Coryphantha vogtherriana is local to the same state and there are some similarities-picture from cactiguide:

It might be related or identical to M. vallensis (see the recent M. magnimamma topic of Maurillo where a nice photo of M. vallensis is shown). Your El Pantano (the only one I found on Google Earth) is not far from Ciudad Valles, which is near Abra Valles, the location of M. vallensis.

Wolter.

Thank you. Will check out M vallensis.