Newly recognised lineages of perithecial ascomycetes: the new orders Conioscyphales and Pleurotheciales

摘要

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 Savoryellales. One clade formed by five species of Conioscypha and a second clade containing several genera of uncertain taxonomic status centred on Pleurothecium, represent two distinct taxonomic groups at the ordinal systematic rank. They are proposed as new orders, the Conioscyphales and Pleurotheciales. Several taxonomic novelties are introduced in the Pleurotheciales, i.e. two new genera (Adelosphaeria and Melanotrigonum), three novel species (A. catenata, M. ovale, Phaeoisaria fasciculata) and a new combination (Pleurotheciella uniseptata). A new combination is proposed for Savoryella limnetica in Ascotaiwania s.str. based on molecular data and culture characters. A strongly supported lineage containing a new genus Plagiascoma, species of Bactrodesmiastrum and Ascotaiwania persoonii, was identified as a sister to the Conioscyphales/Pleurotheciales/Savoryellales clade in our multilocus phylogeny. Together, they are nested in a monophyly in the Hypocreomycetidae, 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 Hypocreomycetidae 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; Phragmocephala stemphylioides is a member of the Pleurotheciales and Triadelphia uniseptata is within the Savoryellales.