An overview of the systematics of the Sordariomycetes based on a four-gene phylogeny

Abstract

The Sordariomycetes is one of the largest classes in the Ascomycota, and the majority of its species are characterized by perithecial ascomata and inoperculate unitunicate asci. It includes more than 600 genera with over 3000 species and represents a wide range of ecologies including pathogens and endophytes of plants, animal pathogens and mycoparasites. To test and refine the classification of the Sordariomycetes sensu Eriksson (2006), the phylogenetic relationship among 106 taxa from 12 orders out of 16 in the Sordariomycetes was investigated based on four nuclear loci (nSSU and nLSU rDNA, TEF and RPB2), using three species of the Leotiomycetes as outgroups. Three subclasses (i.e. Hypocreomycetidae, Sordariomycetidae and Xylariomycetidae) currently recognized in the classification are well supported with the placement of the Lulworthiales in either a basal group of the Sordariomycetes or a sister group of the Hypocreomycetidae. Except for the Microascales, our results recognize most of the orders as monophyletic groups. Melanospora species form a clade outside of the Hypocreales and are recognized as a distinct order in the Hypocreomycetidae. Glomerellaceae is excluded from the Phyllachorales and placed in Hypocreomycetidae incertae sedis. In the Sordariomycetidae, the Sordariales is a strongly supported clade and occurs within a well supported clade containing the Boliniales and Chaetosphaeriales. Aspects of morphology, ecology and evolution are discussed.

• classification
• ecology
• evolution
• Hypocreomycetidae
• Sordariomycetidae
• Xylariomycetidae

We thank Meredith Blackwell and Joseph W. Spatafora for suggestions in the improvement of this manuscript and Walter Gams for assistance with the Latin diagnosis. We are grateful to Robert Shoemaker for photographs of Cainia, Gaeumannomyces and Hypomyces, Gary J. Samuels for photographs of Hypocrea, and David Farr for the photograph of Valsella. We also appreciate assistance and advice with computational resources by Scott Givan and Chris Sullivan at the Center for Gene Research and Biotechnology of Oregon State University. Ben O’Rourke was great assistance to us in generating sequence data. Financial support from the National Science Foundation (DEB-0090301) to Meredith Blackwell, Joseph W. Spatafora and John W. Taylor is greatly acknowledged in initiating the collaboration and publishing this manuscript. Sequence data was generated with financial support from the National Science Foundation (DEB-0228725 and DEB-0129212) to Joseph W. Spatafora.