<jats:p>The depside dissectic acid [methyl 3-(3′-formyl-2′,4′-dihydroxy-6′-methylbenzoyloxy)-4,6-dihydroxy-2,5-dimethylbenzoate] (2) has been isolated from the lichen Heterodermia dissecta together with atranorin (1). The structure of the compound (2) followed from a combination of spectroscopic data and was confirmed by synthesis.