Date: 1996 November 4
Location: in cultivation, San Luis Potosí
I am presuming that this plant is Mammillaria luethyi, published by G.S. Hinton in Phytologia, January 1996. This publication must not have emerged until much later than this date, as the article refers to finding the plant in Northern Coahuila on May 19 1996.
This species is the one referred to by Backeberg in his Cactus Lexicon. Only having seen photographs of the plant, he thought it might be referable to Neogomesia.
Thanks are due to W. Fitzmaurice for allowing the plant to be photographed.
The plant soon 'escaped' into cultivation outside Mexico, but for a long time I refused to buy one, knowing that none had been legally exported. In 2002, Jonas Luethy, for whom the plant is named, told me that he had finally been given one, and thought that he must be among the last Mammillaria enthusiasts to acquire one. So I finally acquired a couple of plants which flowered in April 2003.