The following new xanthones are shown to co-occur in various combinations with other known naturally occurring xanthones: 2-chloronorlichexane (in Lecanora populicola Lecanora sp.), 7-chloronorlichexanthone (in Lecanora populicola, Lecanora sp.), 5-chloro-6-O- methylnorlichexanthone (in Lecanora contractula), 5-chlorolichexanthone (in Lecanora contractula), 7-chloro-6- 0- methylnorlichexanthone (in Lecanora populicola, L. salina, L. sp.), 2,4-dichloronorlichexanthone (in Lecidella vorax), 2,7-dichloro-3-O-methylnorlichexanthone (in Lecanora behringii, L. salina, L. sp.), 2,7-dichloro-6-O-methylnorlichexanthone (in Lecanora behringii, L. populicola, L. salina, L. sp.), 2,5, 7-trichlorolichexanthone (in Lecanora broccha), 4,5, 7-trichloro-6-O-methylnorlichexanthone (in Pertusaria pycnothelia var. A), 3-O-methylthiophanic acid (in Lecidella meiococca), and 6-O-methylthiophanic acid (in Micarea isabellina). Griseoxanthone C (3-0-methylnorlichexanthone) is reported for the first time from a lichen (Lecanora vinetorum). The joint occurrence of these chloroxanthones has been rationalized in biosynthetic terms and represented in a series of pathway diagrams. All were found to constitute coherent arrays of major xanthones and biosequentially related satellite derivatives. In so doing we have established the methodologyfor predicting expected co-occurrences and completing similar data sets for other xanthone-containing species. The many secondary metabolites found in the lichen-forming fungi continue to play a dominant role in the systematics of these organisms because of the extensive parallels with morphology and their clear ecological significance.