Oropogon loxensis produces atranorin, protocetraric acid, salazinic acid, and three new depsides: 2'-O-methylatranorin, methyl 3-a-hydroxy-4-O-demethylbarbatate, and methyl 4-O-demethylbarbatate. The joint occurrence of these compounds and an analysis of structural patterns among the 41 known β-orcinol derivatives support a biogenetic hypothesis involving C-methylation and/or C-formylation at the polyketide stage and a metabolic grid of redox reactions of aromatic precursors leading to the para-depsides, depsidones, benzyl esters, and meta-depsides typical of lichens. INDEX DESCRIPTORS: Lichens; Oropogon loxensis; chemosyndromic variation; β-orcinol derivatives; atranorin; 2'-O-methylatranorin; methyl 3-α-hydroxy-4-O-demethylbarbatate; methyl 4-O-demethylbarbatate; protocetraric acid; salazinic acid.