A revision of the lichen genus Hypotrachyna (Ascomycotina: Parmeliaceae) in Papua New Guinea has shown it to comprise 39 species. Five species are described as new to science: Hypotrachyna hnatiukii, H. lichesterinica, H. malesiana, H. monticola and H. munduai. Six species are new records for Papua New Guinea namely, Hypotrachyna adjuncta, H. andensis, H. galbinica, H. immaculata, H. kayaensis and H. peruviana. Nine of the 39 species are considered endemic to Papua New Guinea. A key and descriptions of the species are given, and the synonymy, chemistry, distribution, ecology and taxonomic affinities of each species discussed. In addition, two species of Myelochroa, one species of Parmelinella and seven species of Parmelinopsis have been identified from Papua New Guinea, and these are also described. Parmelinopsis afrorevoluta and P. protocetmrica are reported for the first time from Papua New Guinea.