Guiggi A., Mexico: Nomenclatural Revision in Cactaceae IV, Cactology, 2022, 5(Supplementum XIII):2-3
The nomenclatural revision publishes the combinations Oehmea sphacelata, O. sphacelata subsp. viperina and O. tonalensis, identifies basionyms and type material, and discusses morphological similarity among the taxa combined. The rationale refers to Buxbaum's Oehmea diagnosis and earlier treatments of the Mammillaria group.