This first version of the Red List of lichens of the Czech Republic uses IUCN criteria version 3.1 for evaluating the species (no infraspecific taxa are included). The Red List is at the same time a new version of the checklist of lichens of the Czech Republic. Differences from the previous checklist published in the Catalogue of lichens of the Czech Republic in 1999 are: 98 species are excluded (non-lichenized fungi, species not documented in the Czech Republic, misidentifications, doubtful/dubious records and other errors) and nomenclatural changes are listed in the chapter on synonyms. In total, 1497 species of lichenized fungi (without lichenicolous and lichen-allied fungi) are included. Of these, 120 (8%) suspicious records and taxonomically problematic or not well explored taxa were not evaluated against the IUCN criteria (NE category). In total, 560 species (37.4%) are threatened: 130 (8.7%) are critically endangered (CR), 184 (12.3%) are endangered (EN) and 246 (16.4%) are vulnerable (VU). In addition, 140 species (9.4%) are extinct in the Czech Republic (RE category), 174 species (11.6%) are listed in the category near threatened (NT) and 190 (12.7%) in least concern (LC). In total, 313 species (20.9%) are listed as data deficient (DD) because insufficient data are available for a categorization.
New information is provided on the distribution of 19 species of lichens belonging to the genus Caloplaca (Teloschistales) in the Czech Republic. Six species are new to this country: C. epithallina, C. erodens, C. inconnexa, C. phlogina, C. polycarpa and C. thuringiaca. The species C. albolutescens, C. cerinella, C. chlorina, C. chrysodeta, C. dichroa, C. flavocitrina, C. herbidella and C. marmorata are reported from the Czech Republic, but little is known about their distribution in this country. Caloplaca biatorina, C. obliterans, C. rubelliana, and C. xantholyta are rediscovered after more than 50 years. The presence of Caloplaca crenulatella, recently reported as new to this country, is confirmed and is actually one of the most common species of this genus. Ecological and chorological data are given for each species, and taxonomic and nomenclatural notes for C. albolutescens and C. chlorina are amended.