Lichens consist of a fungal component that associates with either a green alga or cynobacterium, resulting in diverse morphologies. Resynthesis experiments of isolated myco- and photobionts, as well as internal transcribed spacer (ITS) rDNA phylogenies, suggest that the notoriously dissimilar photomorphs of Lobaria fendleri (Tuck. ex Mont.) Lindau and Lobaria amplissima (Scop.) Forss. both have a single mycobiont, which can simultaneously lichenize two unrelated photobionts, a eukaryote and a prokaryote. In the phylogenetic analyses, the genera Sticta and Durietzia appear monophyletic; whereas Lobaria and Pseudocyphellaria are both nonmonophyletic. Furthermore, the phylogenetic relationships of Durietzia, Lobarina, and Sticta relative to Lobaria and Pseudocyphellaria are in need of re-evaluation.Key words: internal transcribed spacer (ITS), photosymbiodeme, phylogeny, lichen-forming fungi, Lobaria amplissima, Lobaria fendleri, Pseudocyphellaria, Sticta.