Phylogenetic study of Diploschistes (lichen-forming Ascomycota: Ostropales: Graphidaceae), based on morphological, chemical, and molecular data

The genus Diploschistes includes crustose lichen-forming fungi with a carbonized proper excipulum with lateral paraphyses, and a chemistry dominated by orcinol depsides. However, the taxon D. ocellatus lacks these excipular characters and has β-orcinol depsidones, raising doubts about its inclusion within this genus. Using a two-locus dataset (mtSSU, nuLSU), our phylogenetic analyses confirm the classification of D. ocellatus within Diploschistes. Three different groups have been recognized within this genus, based on ascomatal morphology: Actinostomus (perithecioid), Scruposus (urceolate), and Ocel- latus (lecanoroid). These groups have been widely used in monographic studies and keys, but their taxonomic value has not been confirmed yet. Here we inferred phylogenetic relationships within Diploschistes, with a special emphasis on the D. scruposus complex, using a combined dataset consisting of morphological, chemical, nrITS, and mtSSU data in order to determine if these species groups and phenotypically based species delimitations were monophyletic. Based on our results, a new subgeneric treatment for Diploschistes is proposed, and the taxonomic value of fruiting body types is confirmed. The clade correspond- ing to D. ocellatus consists of two well-supported subclades, one of them grouping specimens without ascomata, having only pycnidia. It is also remarkable that the clade containing specimens of D. diacapsis subsp. neutrophilus appears distantly related to the clade containing all other accessions of D. diacapsis. Our analysis revealed that for some taxa, such as D. scruposus and D. interpediens, molecular variability did not correlate with either morphological or chemical diversity.