Molecular phylogenetic studies on tropical species of Lecanora sensu stricto (Lecanoraceae, Ascomycota)
Papong, Khwanruan; Boonpragob, Kansri; Parnmen, Sittiporn; Lumbsch, H. Thorsten
The genus Lecanora is one of the largest genera of crustose lichens and includes a number of distinct clades. Lecanora sensu stricto is characterized by oxalate crystals in the apothecial margin and the presence of atranorin and/or usnic acid. Currently, the phylogenetic relationships of tropical taxa in Lecanora s.str. are poorly understood. To address the phylogeny of tropical species and to test whether certain characters found predominantly in tropical taxa (usnic acid and dark hypothecium) have evolved several times or not we assembled a data set including two loci (ITS, mtSSU rDNA) of 35 species. Species that contain usnic acid do not form a monophyletic group, suggesting that the presence of this metabolite is of restricted taxonomic importance above the species level. Also species with a dark hypothecium do not form a monophyletic group. Monophyly of both groups was rejected using alternative topology tests. These results suggest that usnic acid and a dark hypothecium are adaptations of tropical Lecanora spp. that evolved several times independently within this clade of lichenized fungi. The placements of the aspicilioid L. subimmersa and the almost biatorine L. flavo-pallida in Lecanora s.str. are supported by our study. Three of the included species, viz. L. achroa, L. caesiorubella, and L. helva were shown to be not monophyletic.