As a result of a lichenological expedition to New Guinea in 1992, 298 new or otherwise interesting taxa, mainly of microlichens and lichenicolous funghi, are presented. These include 269 species recorded for the first time from the island. Of these, 115 were known before from adjacent tropical Asia or Australasia. Another 66 were only known from the areas further away, usually the neotropics or the northern temperate zone, and are new records for tropical Asia and Australasia. The remainder appear to be completely unknown; for these, 6 new genera and 89 new species are described, including one more species from East Africa. New combinations are proposed for 10 species, and 2 genus names and 5 species names are reduced to synonymy. For many species details of morphology and chemistry are given. The total known lichen flora of New Guinea is now ca. 1000 species. The geographical affinities of the lichen flora vary with altitude. While the endemic element seems rather constant at all elevations except above 4000 m, the widespread temperate element increases with elevation, in the same way as the pantropical and the palaeotropical elements decrease. The palaeotropical element includes few taxa which extend into Africa. There is new evidence to show a floristical affinity with New Zealand and temperate Australia.