Asterodiscus and Stigmatodiscus, two new apothecial dothideomycete genera and the new order Stigmatodiscales

During a survey on corticolous Dothideomycetes, several collections with ascospores matching the genera Asteromassaria and Stigmatomassaria (Pleomassariaceae, Pleosporales) were revealed from dead corticated twigs of Acer, Carpinus and Tamarix. Closer morphological examination showed that their ascomata were apothecial, with a hamathecium consisting of septate, branched paraphyses, which are apically swollen at maturity. Several collections were cultured and sequenced, and a Blast search of their nuc 28S rDNA sequences revealed dothideomycetous affiliation, but without a close match to a specific family or order. Phylogenetic analyses of a multigene matrix containing a representative selection of Dothideomycetes from four genes (nuc 18S rDNA, nuc 28S rDNA, rpb2 and tef1) revealed placement within Dothideomycetes but without a supported familial or ordinal affiliation. Based on the phylogenetic analyses and morphological investigations, the new genera Asterodiscus and Stigmatodiscus, with the two new species A. tamaricis and S. enigmaticus, are described and illustrated, and placed in the new family Stigmatodiscaceae and new order Stigmatodiscales.