742 species, including 151 reported for the first time, are treated from Svalbard (exclusive of Bjørnøya). New to science are: Bryocaulon hyperborea Øvstedal (also known from Greenland), Buellia insularis Øvstedal, Lepraria svalbardensis Tønsberg, Placynthium pulvinatum Øvstedal (also recorded from mainland Norway), Rhizocarpon dahlii Øvstedal, R. tephromelae Øvstedal, and Tephromela lucifuga Øvstedal & Tønsberg. New combinations are: Aspicilia major (Lynge) Øvstedal, Aspicilia punctiformis (Lynge) Øvstedal, Cetraria racemosa (Lynge) Øvstedal, Miriquidica picea (Lynge) Øvstedal, and Stereocaulon compactum (I. M. Lamb) Øvstedal. Information on morphology, anatomy, chemistry, substrate preferences and distribution is included for all taxa. Keys to genera and species are provided. Separate keys are provided for sorediate species on rock and on soil/bryophytes. 6 % of the species are defined as cosmopolitan. More than one third has a bipolar distribution, whereas about 60 % are restricted to the Northern Hemisphere, 52 species are high-arctic and lacking from Fennoscandia, and 12 species are at present known as Svalbard endemics.
