No abstract

The Ascomycota are a group of filamentous fungi that occur as saprobes, pathogens, and symbionts. They are of immense industrial, medical, ecological, and economical importance. The search for new markers appropriate for molecular phylogenetic analysis of Ascomycota remains a challenging problem. In this study, we explore the phylogenetic utility of a single copy protein-coding gene, MCM7; newly recognized as useful for inferring phylogenetic relationships among the major classes of the Ascomycota. Our specific goals were to: 1) test the phylogenetic utility of MCM7 for estimating phylogenies at various taxonomic ranks (class and below) with an emphasis on non-lichenized ascomycetes; and, 2) compare the congruence, robustness and resolving power of MCM7-based phylogenies with that of nuclear large subunit rDNA (LSU)-based phylogenies for the same taxon set. A dataset of sequence data for MCM7 as well as LSU was assembled for 80 species belonging to 63 genera of lichenized and non-lichenized ascomycetes in the classes Dothideomycetes, Eurotiomycetes, Geoglossomycetes, Lecanoromycetes, Leotiomycetes, and Sordariomycetes. We obtained 93 new sequences of which 65 are MCM7 and 28 are LSU. MaximumLikelihood and Bayesian analyses were performed using single as well as combined gene datasets and partitions. We also assessed substitution saturation for the MCM7 gene. Results indicate that MCM7 can be used successfully for determining phylogenetic relationships of ascomycetes and provided good resolution and support at half the cost compared to LSU. Phylogenetic informativeness profiles showed that MCM7 was more phylogenetically informative than LSU. The MCM7 gene is also a valuable phylogenetic marker for both lower as well as higher level phylogenetic analyses within the Ascomycota, especially when used in MycoKeysLaunched to accelerate biodiversity research Huzefa A. Raja et al. / MycoKeys 1: 63-94 (2011) 64 combination with the LSU gene. We found that although the third codon position of MCM7 is saturated, it was better to analyze the dataset with all codon positions included. Phylogenetic performance of MCM7 with and without the third codon position is discussed.

The class Geoglossomycetes is a recently created class of Ascomycota, currently comprised of one family (Geoglossaceae) and five genera (Geoglossum, Nothomitra, Sarcoleotia, Thuemenidium and Trichoglossum). These fungi, commonly known as earth tongues, have long been a subject of mycological research. However, the taxonomy within the group has historically been hindered by the lack of reliable morphological characters, uncertain ecological associations, and the inability to grow these fungi in culture. The phylogenetic relationships of Geoglossomycetes were investigated by conducting maximum likelihood and Bayesian analyses using a 4-gene dataset (ITS, LSU, MCM7, RPB1). Five well-supported monophyletic clades were found that did not correspond exactly with the currently recognised genera, necessitating a taxonomic revision of the group. Two new genera are proposed: Glutinoglossum to accommodate G. glutinosum and the newly described species G. heptaseptatum, and Sabuloglossum to accommodate S. arenarium. The type species of Thuemenidium, traditionally included within the Geoglossaceae, is confirmed as belonging to a separate lineage that is only distantly related to Geoglossomycetes.

No abstract

Glutinoglossum is a recently described genus in Geoglossomycetes, characterized by viscid black fruiting bodies. Glutinoglossum was described based on molecular evidence showing that the fungus formerly known as Geoglossum glutinosum formed a well-supported clade separate from Geoglossum. This study provides a comprehensive examination of Glutinoglossum based on maximum-likelihood and Bayesian analyses of a dataset that includes nuc rDNA internal transcribed spacer and partial 28S regions and the nuc genes for RNA polymerase II largest subunit (RPB1) and minichromosome maintenance complex component 7 (MCM7). Four new species are described, an emended description of Glutinoglossum glutinosum and a key to the genus Glutinoglossum is provided.