Ortegocactus macdougallii

Ortegocactus macdougallii is a species of cactus, the sole species of the genus Ortegocactus and closely related to Mammillaria. The plant has a greenish-gray epidermis and black spines. It is only known from Oaxaca, Mexico where it grows on limestone rock. It is often grafted since it is tricky to grow when on its own roots. A harmless but unsightly orange discoloration is common at the base of the stems. It named in honor of the family Ortega, from San Jose Lachuguiri that helped Tom MacDougall in the discovery of this plant.

The plant above is growing in a 3" pot and purchased a couple of years ago. I like the contrast of the spines against the body of the plant.