Towards a natural classification and backbone tree for Graphostromataceae, Hypoxylaceae, Lopadostomataceae and Xylariaceae

Species and generic recognition in the order Xylariales has been uncertain due to lack of molecular data from authentic cultures, as well as overlapping morphological characteristics. In this study, we revise the families Graphostromataceae, Hypoxylaceae, Lopadostomataceae and Xylariaceae in Xylariales. Our study is based on DNA sequence data derived from living cultures of fresh isolates, data from GenBank and morphological observation of type and worldwide herbarium specimens. We also collected new specimens from Germany, Italy and Thailand. Combined analyses of ITS, LSU, RPB2 and beta-tubulin sequence data were used to reconstruct the molecular phylogeny of the above families. Generic and familiar boundaries between these families are revised and presented in an updated combined phylogenetic tree. We accept six genera in Graphostromataceae, 19 genera in Hypoxylaceae, four in Lopadostomataceae and 37 genera in Xylariaceae. Five genera previously treated in Xylariaceae are placed in Amphisphaeriales genera incertae sedis and seven genera are placed in Xylariales genera incertae sedis. Two genera are placed in Sordariomycetes genera incertae sedis, while four genera are placed as Xylariomycetidae genera incertae sedis. Three genera are considered as doubtful. Barrmaelia and Cannonia, presently included in Xylariaceae are transferred to Diatrypaceae and Coniochaetales respectively, based on their morphology and phylogeny. Areolospora and Myconeesia are excluded from Xylariaceae and synonymized with Phaeosporis and Anthostomella respectively. Updated descriptions and illustrations are provided for all taxa with notes provided on each genus. Excluded and doubtful genera are listed with notes on their taxonomy and phylogeny. Taxonomic keys are provided for all revised families with morphological details for genera within the families.