Newly recognised lineages of perithecial ascomycetes: the new orders and .

Phylogenetic analyses of DNA sequences from nuclear ribosomal and protein-coding loci support the placement of several perithecial ascomycetes and dematiaceous hyphomycetes from freshwater and terrestrial environments in two monophyletic clades closely related to the . One clade formed by five species of and a second clade containing several genera of uncertain taxonomic status centred on , represent two distinct taxonomic groups at the ordinal systematic rank. They are proposed as new orders, the and . Several taxonomic novelties are introduced in the , i.e. two new genera ( and ), three novel species (, , ) and a new combination (). A new combination is proposed for in s.str. based on molecular data and culture characters. A strongly supported lineage containing a new genus , species of and , was identified as a sister to the // clade in our multilocus phylogeny. Together, they are nested in a monophyly in the , significantly supported by Bayesian inference and Maximum Likelihood analyses. Members of this clade share a few morphological characters, such as the absence of stromatic tissue or clypeus, similar anatomies of the 2-layered ascomatal walls, thin-walled unitunicate asci with a distinct, non-amyloid apical annulus, symmetrical, transversely septate ascospores and holoblastic conidiogenesis. They represent the only fungi in the with apically free, filiform to cylindrical, persistent or partially disintegrating paraphyses. The systematic placement of two other dematiaceous hyphomycetes was resolved based on DNA sequences; is a member of the and is within the .