it has been argued that the said hybrid plant is some form of unknown monstrose mammillaria, or a mammillaria hybrid, or another intergeneric hybrid involving a mammillaria and another cactus, based on the notion that the two supposed parents are too distant for a cross to be possible and the flowers are borne in a ring around the plant (like mammillaria).
granted, it does have the thick fleshy roots of the E.knippelianus (which are incredibly pink!), flat spines like Toumeya (a very uncommon feature for mammillaria), as well as white radial spines and large white areoles like toumeya.
yep well in any case it is worth a shot.