Structure and identification
The stem is flattened, hemispherical or spherical, tapering towards the base and supported by fibrous roots. Tubercles have a broad base and flattened upper side. Lateral spines are strong, some curving towards the surface, while upper ones are thinner and clustered. A single central spine may be present in only some areoles. Flowers are yellow, and elongated green fruits contain light brown seeds. [Dicht and Lüthy 2005, p. 68–69]
Habitat and variation
The monograph documents the species on grassy lava substrates in Puebla and Oaxaca. It also describes local plants with more golden-yellow spines, formerly called C. melleospina. Variation in armature colour includes a transition from yellowish new growth to the white and grey of older spines. [Dicht and Lüthy 2005, p. 68–69]
Related articles
Synonyms and names in the literature
Cactus retusus · Coryphantha melleospina · Coryphantha retusa var. melleospina · Coryphantha retusa var. pallidispina · Mammillaria retusa · Melocactus cephalophora · Melocactus mammillariiformis [2-WWW]