Wow, don't know what to make of this plant, looks like it's part Ariocarpus, part Mammillaria, part Pelecyphora. Crazy stuff. Amazing that we are still finding new plants today....not so amazing that plants or seed have already been illegally taken from habitat...
Further info in Xerophila 11 http://xerophilia.ro/
And Cactus Explorer 12 http://www.cactusexplorers.org.uk/journal1.htm