Lecanora demissa (Körb.) Zahlbr. is a crustose, lobate lichen that produces soredia and conidiomata but no apothecia. Its placement in Lecanora has long been questioned but nothing better has been proposed. We have studied the nuclear rDNA of the ITS regions and the SSU of L. demissa. In an alignment of the ITS regions of several representatives of Lecanora s. lat. it could clearly be shown by a PAUP analysis, using Aspicilia caesiocinerea as outgroup, that L. demissa does not belong to Lecanora. In a PAUP analysis of sequences of the SSU from representatives of the order Lecanorales, using members of Saccharomycetales as outgroup, L. demissa clustered on a well-supported branch with Caloplaca chlorina. In a further analysis of the ITS sequences of L. demissa together with representatives of Caloplaca and Xanthoria using Protoparmelia as outgroup two most parsimonious trees were found. In these trees the L. demissa branch was well within a strongly supported clade with C. cerina, the type species of the genus Caloplaca. The sister taxon to L. demissa in this analysis was C. variabilis. Chemical data and characters of the conidiomata support the affinity with Caloplaca and the new combination C. demissa (Körb.) Arup & Grube is therefore proposed. A lectotype for Imbricaria demissa has been designated. The phylogenetic analysis of several representatives of the genera Caloplaca and Xanthoria suggests that these genera are not monophyletic as presently circumscribed. Two large, monophyletic groups of species could be recognized, one with Xanthoria species mixed with lobate and crustose members of Caloplaca, and one with mainly crustose Caloplaca, including both species with orange or black apothecia.