In Norway’s first flora the author, Ernst Gunnerus (1718-1773), records no less than 77 lichen species, eight of which are described as new. Only one of them, Lichen (=Cornicularia) normoericus, is based on specimens in his herbarium. The others are based on information from professor Oeder in København, five with illustrations in ‘Flora danica’ which need interpretation. Two of these, Lichen groenlandicus and Lichen heclae, have remained untypified, which is rectified here. Lichen heclae is a later synonym of Placopsis gelida (L.) Linds. Lichen groenlandicus proved to be an overlooked name in the Peltigera canina complex, here lectotypified by the illustration in ‘Flora danica’. According to exsiccate material from the region where the original collection was made, it represents the recently described Peltigera islandica Goward & Manoharan-Basil, an isotype of which confirms this interpretation and is designated as epitype of the cited illustration. The necessary combination into Peltigera is made. The new taxonomy of Rhizocarpon requires a new combination: Rehmia oederi (Gunnerus) P.M. Jørg. (= Rehmia petraeum (Wulfen) E.J. Möller et al.). Two further species which were named as new by Gunnerus, but without any known specimens, are discussed.