Commemorating the Ortega family of San José Lichiguiri, Oaxaca, Mexico who assisted in the discovery of the plant.
Body grey-green, spherical to shortly cylindrical, mostly less than 4 cm wide and forming clusters. Tubercles large, mostly over 1 cm wide and covered with minute dots. Areoles white woolly with upper and lower regions as in Mammillaria. Spines mostly black-tipped; radials 7-8 to 1 cm long, central spine 1, 4-5 mm long. Flower diurnal, to 3 cm long, hairy, yellow. Pericarpel naked; flower tube short and surrounded by wool. Fruit dry, dark red.
Known through the sole species O. macdougalii Alex. Sometimes grown as grafts.
Intermediate in characters between Mammillaria and Escobaria and sometimes placed in Neobesseya. The large tubercles are reminiscent of Coryphantha but without the upper groove.
1 species from SE Mexico (Oaxaca).
Source: (1997). Cactaceae. In: . Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.
