ISSN (print) 0093-4666 © 2011. Mycotaxon, Ltd. ISSN (online) 2154-8889 MYCOTAXON http://dx.doi.org/10.5248/117.405 Volume 117, pp. 405–422 July–September 2011 The genus Cladonia (lichenized Ascomycota, Cladoniaceae) in South Korea Xin Yu Wang 1 , Yogesh Joshi 1,2 & Jae-Seoun Hur 1 * 1 Korean Lichen Research Institute, Sunchon National University, Sunchon 540-742, Korea 2 Department of Botany. S.S.J. Campus, Almora 263601, Uttarakhand, India * Correspondence to: jshur1@sunchon.ac.kr Abstract — During a comprehensive study of Cladonia from South Korea, 41 taxa were recognized, including C. dehiscens, C. floerkeana, C. macroptera, and C. rappii var. exilior, new to South Korea. Brief information and discussion are provided for each taxon, together with a key to the taxa recorded from South Korea. Key words — lichen-forming fungus, taxonomy, new records Introduction Cladonia is one of most common lichen genera, widely distributed on all continents and including more than 400 species worldwide (Ahti 2000). Park (1990) was the first to conduct an expert study of lichens in South Korea. Her ‘Macrolichen flora of South Korea,’ however, included only 22 Cladonia species, and the omission of many species we have since collected has made identification difficult. hus, we began comprehensive research on the genus in South Korea with extensive field surveys from 2003 to 2010 and found several Cladonia species previously not known in this country. Here we provide information for 41 Cladonia taxa and a key to the South Korean species. Here we follow the taxonomic system set forth by Ahti (2000), separating South Korean Cladonia into five sections based on the secondary metabolites as identified by High Performance Liquid Chromatography (HPLC): Cladonia, Cocciferae, Helopodium, Perviae, and Unciales. Cladina is treated as a subgenus of Cladonia. Material and methods We examined 496 Cladonia specimens collected during 2003–2010 in South Korea, and deposited in the Korean Lichen Research Institute (KoLRI), Sunchon National University. External morphological descriptions were based on air-dried material, and