Abstract
Cryptothecia austrocoreana is a new lichen species from South Korea. The species is characterized by the presence of a heteromerous thallus and faveolate ascigerous area (ascomata) immersed in a slightly raised thallus. The species has muriform ascospores, (4)6-8-spored 8-11 × 3-4 septate, (34)36-48(51) × (17)19-23(25) μm. Atranorin, chloroatranorin, and barbatic acid are present. In the phylogenetic tree, C. austrocoreana belongs to the arthonioid clade in Arthoniaceae.