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, rpb 2 and tef 1) 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 .