In flower today, a few different forms of moelleriana / cowperi.
Mammillaria moelleriana 'cowperi' WK138 from San Juan de Los Hornillos, ZAC-54, km 29.0, Zacatecas
Mammillaria moelleriana 'cowperi' Rog 077 from the same location as the previous
Mammillaria moelleriana with no location data.
Mammillaria moelleriana Lau 694
It is interesting how the flower colour varies, even with pale spined plants, from yellow to pale pink, and then darker pink with the Lay collection.