Psoroglaena humidosilvae Lee is described as a new lichen species from a wetland forest in South Korea. The new species is distinct from P. stigonemoides (Orange) Henssen by little projections locally present on the thallus; smaller, paler, and globose perithecia; smaller asci; and smaller ascospores generally 3-septate. Molecular analyses employing internal transcribed spacer (ITS), mitochondrial small subunit (mtSSU), and nuclear large subunit ribosomal RNA (LSU) sequences strongly support P. humidosilvae as a nonidentical species in the genus Psoroglaena. A surrogate key is provided to assist in the identification of all 22 species of Psoroglaena. Keywords: biodiversity; corticolous; phylogeny; taxonomy; Verrucariaceae.