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Title:A circumscription of the earth tongue fungi class Geoglossomycetes
Author(s):Hustad, Vincent Patrick
Director of Research:Miller, Andrew N.
Doctoral Committee Chair(s):Miller, Andrew N.
Doctoral Committee Member(s):Seigler, David; Dalling, James W.; Levin, Geoffrey A.
Department / Program:Plant Biology
Discipline:Plant Biology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Cryptic Speciation
Abstract:The earth tongue fungi are a relatively small but captivating group of fungi that have fascinated mycologists for over three hundred years. From the first mention of “Fungus ophioglossoides” in 1667 to the latest molecular genomic studies, earth tongues have often been on the cutting edge of mycological research. In the following dissertation, I present the results of six years of research into the earth tongue class Geoglossomycetes. I began my research shortly after the official breakup of the family Geoglossaceae sensu lato in 2009. At the beginning of my study, only three genera and 43 species were accepted in the class. Today, as a result of my research and others, a total of nine genera and over 70 species are considered to belong in Geoglossomycetes, and knowledge of their distribution and ecology has greatly increased. My research has served to provide a stable taxonomy and molecular framework for new and exciting studies, facilitating mycological research across a number of subjects including fungal conservation, ecology, and systematics and evolution of Ascomycota. Chapter One is a general introduction to the earth tongue fungi, cataloguing over three hundred years of mycological research on the topic. My first project (Chapter Two) is a small phylogenetic study examining the genus Nothomitra that was completed and published in 2011. Nothomitra was originally described in the family Geoglossaceae sensu lato, but following the redefinition of the family in 2009, the genus was considered incertae sedis within Helotiales. This study used a combined morphological and molecular approach using two regions of nuclear rDNA (ITS and LSU) and the protein-coding gene MCM7. Our dataset of 22 taxa, including 13 ingroup species, was the largest publicly available data set of Geoglossomycetes at that time. In this study, we presented molecular and morphological evidence supporting the placement of Nothomitra in Geoglossomycetes, clarifying the position of Nothomitra as a basal member of Geoglossomycetes, most closely aligned with the genus Sarcoleotia. Both Nothomitra and Sarcoleotia are characterized by capitate fertile hymenia clearly distinct from the sterile stipe, hyaline aseptate ascospores, and habitat in disturbed soil. This study included the first use of MCM7 in a phylogenetic study of Geoglossomycetes and the inclusion of Nothomitra in Geoglossomycetes greatly elucidated the basal relationships of the Geoglossomycetes clade. Chapter Three is a large phylogenetic study of Geoglossomycetes that was completed and published in 2013. This study used a combined morphological and molecular approach including the ITS and LSU regions of nuclear rDNA, as well as the protein-coding genes MCM7 and RPB1, to examine the largest dataset of Geoglossomycetes (24 total taxa, 15 ingroup species) publicly available at that time. In this study, we presented evidence showing that the viscid earth tongue, Geoglossum glutinosum, formed a separate and distinct lineage from the genus Geoglossum. We described the cryptic species Glutinoglossum heptaseptatum, that was separated from Glutinoglossum glutinosum by molecular and morphological data. Additionally, we described the genus Sabuloglossum to accommodate the species, Sabuloglossum arenarium, a species that is conservationally important in several European countries due to the rarity of occurrence and fragile habitat. Chapter Four is a project examining the issue of epitypification and the importance of using material of recent provenance in modern taxonomic mycological research that was completed and published in 2014. The focus of this project is the species Geoglossum simile, a species that is common in North America, but rare in Europe. The species was originally described in the late 19th century, but the original type specimen has been lost and only a few fragments of the syntype specimen remain. I examined collections of G. simile from North America and Europe and found all Northern Hemisphere collections to be conspecific based on morphological and molecular data. We also designated a recent collection from North America as the epitype of the species. Chapter Five is a monographic study of the genus Glutinoglossum that was completed and published in 2015. In this chapter, four new cryptic species of Glutinoglossum were described: G. americanum from North America, G. australasicum from Australasia, G. exiguum from Australasia, and G. methvenii from New Zealand. As a result of this study, six species of Glutinoglossum are recognized, all of which were formerly considered to belong under one name, Geoglossum glutinosum. This study exemplifies the ubiquity of cryptic species in Geoglossomycetes and suggests that the class is likely highly more diverse than previously understood. Chapter Six is a study of the genus Maasoglossum completed and published in 2015. Maasoglossum is a rare genus of earth tongues described from temperate forests in the Eastern Himalayas in 1984. The genus Maasoglossum was described to accommodate a single species, M. verrucisporum, a rare species known only from a single collection. In this project, I elucidated the position of Maasoglossum as a basal member of Geoglossomycetes, most closely related to Nothomitra and Sarcoleotia. The peculiar morphology and habitat of these three genera provide an interesting insight into the evolution of Geoglossomycetes and illustrates the likely evolution of several characters of Geoglossomycetes separating these fungi from the closely related Leotiomycetes. Chapter Seven is a comprehensive phylogenetic examination of Geoglossomycetes. Each of the nine genera of Geoglossomycetes is discussed in detail including Hemileucoglossum, which was circumscribed by Sabino Arauzo in 2014 to contain four species previously considered members of the genus Geoglossum.
Issue Date:2015-07-16
Rights Information:Copyright 2015 Vincent Hustad
Date Available in IDEALS:2015-09-29
Date Deposited:August 201

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