Phylogenetic study of Fulgensia and allied Caloplaca and Xanthoria species (Teloschistaceae, lichen-forming ascomycota)

Fulgensia MassaL. & De Not. is a widespread genus with considerable morphological and ecological heterogeneity across species. For this reason, the taxonomic delimitation of this genus has been controversial. Relationships among species of Fulgensia, Caloplaca Th. Fr., and Xanthoria (Fr.) Th. Fr. (Lecanorales) were investigated based on a comprehensive phylogenetic analysis of 62 DNA sequences from the nuclear ribosomal internal transcribed spacer (ITS) region using maximum parsimony (MP) and likelihood (ML). Ambiguously aligned (INAASE coded characters) and unambiguous regions were analyzed separately and combined when using MP as the optimization criterion. All our analyses confirm the polyphyly of this genus as three distinct lineages: Fulgensia sensu stricto, F. australis, and F. schistidii. We report here that Caloplaca, Fulgensia, and Xanthoria together form two main sister lineages. One lineage includes Fulgensia schistidii (part of the C. saxicola group), Xanthoria, and most of the lobed Caloplaca species belonging to the Gasparrinia group. A second main lineage comprises the remaining Caloplaca species, Fulgensia sensu stricto, and F. australis. Therefore, the traditional generic level classification schemes for the family Teloschistaceae appear to be highly artificial. All three genera were found to be nonmonophyletic. We demonstrate here that the ITS is appropriate to resolve relationships across the Teloschistaceae. However, a combination of an MP analysis, in which ambiguously aligned regions are accommodated using INAASE, with an ML analysis, in which phylogenetic confidence is estimated using a Bayesian approach, is needed.