The phylogeny of Arthoniales (Pezizomycotina) inferred from nucLSU and RPB2 sequences

A two-locus phylogenetic study of the order Arthoniales is presented here using the nuclear ribosomal large subunit (nucLSU) and the second largest subunit of RNA polymerase II (RPB2). This analysis is the first large phylogeny of this fungal group and includes 476 sequences and 240 specimens representing 132 species sampled from 31 genera (in their traditional circumscription). In addition to the previously recognized families (Arthoniaceae, Chrysothricaceae and Roccellaceae), three additional family-level groups are recovered, one being poorly supported. Therefore, the new family Roccellographaceae is described and the family Opegraphaceae is reinstated. Morphological characters such as growth form, fruit body type, exciple, hypothecium and ascospores colour, ascospores septation pattern, and chemistry are found to be of limited use in delimiting families and genera, which indicates an unusual level of plasticity in the Arthoniales. This high level of homoplasy might indicate that the Arthoniales is an old group with taxa having evolved in parallel for very long times. The genera Arthonia, Arthothelium, Chiodecton, Hubbsia, Ingaderia, Lecanactis, Lecanographa, Llimonaea, Opegrapha, Roccellina, Schismatomma and Sclerophyton were found paraphyletic. In order to make these genera monophyletic, the new genera Dimidiographa, Fulvophyton, Paraingaderia, Paralecanographa, Paraschismatomma and Sparria are newly described and the genera Alyxoria, Dictyographa and Zwackhia reinstated. The new species Lecanactis borbonica and Paraingaderia placodioidea are described.