Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy



Major Professor

Ronald H. Petersen

Committee Members

Edward Schilling, Roy E. Halling, David K. Smith, Ernest C. Bernard


The genus Marasmius (Tricholomataceae, Agaricales, Basidiomycotina) constitutes one of the larger genera of litter-decomposing and litter-binding mushrooms, represented worldwide by approximately 500 species. Thirty-eight taxa representing eight sections of the genus are recognized as occurring in the southern Appalachian Mountains. Seven of these taxa are new to science, while an additional 14 are reported for the first time from the study area. In addition, one new section is proposed.

Descriptions of southern Appalachian species of Marasmius have been compiled from data on macro- and micromorphological features of basidiomata, supplemented with data on geographical and ecological distribution. Details on nomenclature and comparisons with phonetically similar taxa are provided, as are illustrations of diagnostic micromorphological characters. Dichotomous keys to the sections and species of southern Appalachian Marasmius are presented, and a preliminary key to Marasmius from North America is offered.

The taxonomic potential of cultural morphology and spot tests for phenoloxidase activity have been analyzed. Descriptions of culture mat morphology of 29 taxa grown on Malt Extract Agar (MEA) and Potato Dextrose Agar (PDA) are presented, and s synoptic key to aid in their diagnosis is provided. These studies indicated that culture mat morphology as developed on MEA was similar for most taxa, and consequently of limited taxonomic value. Conversely, culture mat morphology developed on PDA was distinctive and taxonomically useful for each taxon examined. Results of spot tests for phenoloxidase activity indicate that cultures of all taxa examined showed laccase activity, while basidiomata of the same taxa showed no laccase activity. In comparison, cultures and corresponding basidiomata of some species showed tyrosinase activity, while other taxa showed no tyrosinase activity. Spot tests for tyrosinase activity proved taxonomically useful.

To clarify the taxonomy and nomenclature of southern Appalachian Marasmius extant type specimens, authentic material of representative material of 217 species have been examined in their correct taxonomic disposition determined. Neotype or lectotype specimens are designated and new combinations are proposed where appropriate.

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