A new species and four new records of Bacidia (Lecanorales, Ramalinaceae) from South Korea, with a key to Korean species.

A new species, Bacidiafuscopallida Lee & Heo and four new records, B.ekmaniana R. C. Harris, Ladd & Lendemer, B.friesiana (Hepp) Körb., B.heterochroa (Müll. Arg.) Zahlbr. and B.suffusa (Fr.) A. Schneid., are described from South Korea. Bacidiafuscopallida differs from B.diffracta S. Ekman, the most similar species, by warted but non-granular thallus, paler and smaller apothecia without pruina, proper exciple without crystals, over 11-septate ascospores and smaller pycnidia and pycnoconidia. Bacidiaekmaniana is recorded new to Asia, B.heterochroa is reported new to northeastern Asia and B.friesiana and B.suffusa are new to Korea. Molecular analyses employing internal transcribed spacer (ITS) sequences strongly support the classification of the five species of Bacidia . A surrogate key is provided to assist in the identification of all 19 taxa in Bacidia of Korea.