Lecanora baekdudaeganensis Lee & Hur is described as a new lichenized fungus from Baekdudaegan Mountains, South Korea. The new species is classified into the Lecanora subfusca group – allophana type and distinguishable from Lecanora imshaugii Brodo by a darker thallus, brownish disc, K–insoluble granules on the surface of the epihymenium, shorter hypothecium, and the presence of oil droplets in the apothecial section. Molecular analyses employing internal transcribed spacer (ITS) and mitochondrial small subunit (mtSSU) sequences strongly support Lecanora baekdudaeganensis as a distinct species in the genus Lecanora. A surrogate key is provided to assist in the identification of all 52 taxa in the genus Lecanora of Korea. Keywords: biodiversity, Lecanoraceae, phorophyte, phylogeny, taxonomy.