A multi-gene study of the phylogenetic relationships of the Parmeliaceae

Three hypotheses of the phylogeny of the lichenized Parmeliaceae are constr ucted, using sequences of the nuclear ribosomal gene cluster (SSU, ITS, 5.8 S rDNA) from Bryonia capillaris, Cetraria islandica, Evernia prunastri, Hyp ogymnia physodes, Parmelia saxatilis, Platismatia glauca, Pleurosticta acet abulum, Usnea florida, Vulpicida juniperina, V. pinastri and Xanthoparmelia conspersa. The first analysis, based on SSU sequences, shows the represent atives of the Parmeliaceae to form a monophyletic group within the order Le canorales. Usnea florida and Bryoria capillaris, sometimes classified in th e families Usneaceae and Alectoriaceae, respectively, are also members of t he Parmeliacceae. Cetraria and Vulpicida form a well-supported monophyletic group together with Usnea, but there is little support for any other group ings within Parmeliaceae. The second analysis is based on ITS an 5.8S seque nce data of the representatives of the Parmeliaceae included in the first a nalysis, and supports the close relation of Cetraria and Vulpicida. Other g roupings are not supported, and the topology also varies greatly with minor alignment changes. This is attributed to the included taxa being too dista ntly related to each other, causing alignment difficulties of the variable ITS region when a relatively small number taxa are included. It is predicte d that a larger sample of phylogenetically intermediate taxa will overcome this problem. When combining the two datasets, the results are similar to t he ITS results. The present study is one of the first phylogenetic studies utilizing the information in more than one gene alone in lichenized ascomyc etes.