Knudsen, KerryLendemer, James CElix, John2015-12-100029-5035http://hdl.handle.net/1885/61023Lecanora peninsularis from the San Jacinto Mountains of southern California in western North America is described as new to science. The species is lignicolous and apparently related to L. crassithallina, presently known only from Mexico. The main diagnostic substances present in the new species are isousnic acid, gyrophoric acid, and 7-O-methylnorascomatic acid.Keywords: Ascomycota; Lecanora; Lecanoraceae Lichenized ascomycota; Lichens; North america; Rare species; Taxonomy201110.1127/0029-5035/2011/0092-01012016-02-24