Until 1990 it was thought that Aztekium was a monotypic genus. Then George Hinton stumbled across the find of the century, Aztekium hintonii. A lttle larger than ritteri, it can get up to 4 inches in diameter. It is similar in appearance having the same furrows across the ribs but tlacks the secondary ribs. When young it can also have wooly areoles which give the impression of a wooly fringe along the ribs. This is very attractive when it grows that way. Cultivation is the same as for ritteri, being found in the same sort of habitat, also in Nuevo Leon. The flowers are prettier, anywhere from pink to deep magenta. I worked the same PSP magic on this pic. When it offsets, I'll try growing one on it's own roots.