Molecular phylogeny of the genus Physconia (Ascomycota, Lecanorales) inferred from a Bayesian analysis of nuclear ITS rDNA sequences

A Bayesian analysis of nuclear ribosomal DNA internal transcribed spacer (ITS) sequences was used to infer phylogenetic relationships of 14 Physconia species. The analysis supports the monophyly of the genus. Three well supported clades can be distinguished within Physconia: the series griseae, venustae and pulverulentae. The relationships of these clades, however, is not resolved with confidence. Cortical characters are re-evaluated on the basis of the phylogenetic hypothesis. Anatomical features of the upper cortex are only diagnostic above the species level for two special forms of two-layered cortices, while morphological characters, such as lower surface and rhizine-type are characteristic for distinct clades. P. venusta and P. perisidiosa are not separated in this analysis, but populations of P. muscigena, and European and North American samples of P. americana are clearly distinct and the monophyly of both P. americana and P. muscigena s. lat. is rejected on the basis of a Bayesian hypothesis testing.