4 NEW LICHEN XANTHONES

The new lichen xanthones 2,5-dichloronorlichexanthone (in Buellia sp.), 2,7-dichloronorlichexanthone (in Buellia sp., Lecanora broccha), 4,7-dichloronorlichexanthone (in Lecidella asema) and 5,7-dichloronorlichexanthone (in Buellia sp., Lecanora broccha, Lecidella asema, Lecidella subalpicida) have been shown to co-occur in various combinations with the known naturally occurring xanthones 2,5-dichloronorlichexanthone, 4,5-dichloronorlichexanthone, isoarthothelin (2,5,7-trichloronorlichexanthone), arthothelin (2,4,5-trichloronorlichexanthone), 4,5,7-trichloronorlichexanthone (asemone), 5,7-dichloro-3-O-methylnorlichexanthone, 2,5,7-trichloro-3-O-methylnorlichexanthone, 4,5,7-trichloro-3-O-methylnorlichexanthone, and thiophanic acid.