The lichen genus Caloplaca (Ascomycota, Lecanoromycetes) on Svalbard. Notes and additions

23 species of the lichen genus Caloplaca from Svalbard are described and/or discussed. The descriptions are natural language descriptions based on characters for each species coded into LIAS (Global Information System for Lichenized and Non-Lichenized Ascomycetes). A total of 37 Caloplaca species are listed for Svalbard, of which two species: C. elvebakkiana and C. scabrosa are described as new to science. C. alaskensis is recorded for the first time from Svalbard. A key to the Caloplaca species known from Svalbard is provided.