Phylogenetic and taxonomic studies within Arthonia Ach. (Ascomycetes, Arthoniales)

Abstract: The taxonomy and phylogeny of the genus Arthonia was analysed. As a first step, a phylogenetic analysis was performed to test the monophyly of some of the infrageneric groups suggested by earlier authors. The results strongly support that Arthonia, Arthothelium and Arthoniaceae are paraphyletic. Five monophyletic clades were revealed within Arthonia. The best supported clade , Arthonia sect. Arthonia, consisted of non-lichenized or poorly lichenized pioneer species, including the type species of Arthonia, A. radiata.A taxonomic revision of this clade in Europe, northern Africa and North America is presented. Descriptions, distribution maps and photographs are given for the 27 recognised species. The systematic history of Arthonia and Arthothelium is reviewed. The morphology, anatomy, chemistry, ecology and distribution patterns of Arthonia sect. Arthonia are described. Keys are given to the genera within Arthoniaceae, to infrageneric groups within Arthonia and to the treated species. A phylogenetic analysis of the 27 recognized species is presented, based on 57 morphological, anatomical, chemical and ecological characters. The analysis resulted in 311 most parsimonious trees. In the strict consensus tree section Arthonia is monophyletic receiving a Bremer support value of two. Arthonia reniformis and A. ruana constitute the sister group of section Arthonia. Relationships within section Arthonia are not fully resolved. A new species, Arthonia tehleri, is described. The following species of Arthothelium are transferred to Arthonia sect. Arthonia: Arthothelium beccarianum (syn. A. sardoum), A. lirellans, A. orbilliferum, A. phlyctiformis (syn. A. taediosoides), and A. subastroideum. The following names have to be changed due to priority reasons: Arthonia crozalsiana (to Arthonia albopulverea), A. epipastoides (to A. glaucella), A. sardoa (to A. beccariana), Arthothelium taediosoides (to Arthonia phlyctiformis).