Lophophora diffusa is attributed to the authority (Croizat) Bravo, reflecting Croizat's earlier work and Bravo's recombination. [Structure, Development, and Taxonomy in the Genus Lophophora]
In L. diffusa the podaria and ribs are poorly developed or lacking, and the pollen structure differs from that of L. williamsii. [Structure, Development, and Taxonomy in the Genus Lophophora]
The accepted name with authority is Lophophora diffusa (Croizat) Bravo; the article recognizes the variety Lophophora diffusa var. koehresii under it. [Hansen 2000 — Lophophora fricii & williamsii var. decipiens]
L. diffusa is treated as a distinct, non-hallucinogenic Lophophora species separate from L. williamsii. [Trout's Notes on the Cultivation & Propagation of Cacti]
Lophophora diffusa has the authority '(Croizat) Bravo', first published in Cactaceas y Suculentas Mexicanas 12: 13 (1967); its basionym is Lophophora echinata var. diffusa Croizat. [https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:143598-2]
Phylogenetics — the DNA story
L. diffusa, the southern population, is interpreted by the authors as representing the ancestral type within the genus, with L. williamsii being the more specialized/derived type. [Structure, Development, and Taxonomy in the Genus Lophophora]
The southern population's pollen is predominantly the simpler tricolpate type, which the authors regard as the ancestral condition, whereas the northern population shows more elaborate, specialized many-colpate grains. [Structure, Development, and Taxonomy in the Genus Lophophora]
Native range
L. diffusa (the southern population) is restricted to the Mexican state of Queretaro. [Structure, Development, and Taxonomy in the Genus Lophophora]
Lophophora diffusa is endemic to central Mexico, with a restricted range in the state of Queretaro (extending toward Hidalgo), occupying the southern end of the genus's overall distribution. [https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:143598-2; https://en.wikipedia.org/wiki/Lophophora]
