Title page for ETD etd-050699-154650


Type of Document Master's Thesis
Author Aime, Mary Catherine
Author's Email Address maime@vt.edu
URN etd-050699-154650
Title Generic concepts in the Crepidotaceae as inferred from nuclear large subunit ribosomal DNA sequences, morphology, and basidiospore dormancy patterns
Degree Master of Science
Department Biology
Advisory Committee
Advisor Name Title
Miller, Orson K. Jr. Committee Chair
Hilu, Khidir W. Committee Member
Scheckler, Stephen E. Committee Member
Keywords
  • Simocybe
  • basidiospore germination
  • Melanomphalia
  • Crepidotus
  • 28S rDNA
Date of Defense 1998-11-19
Availability unrestricted
Abstract
The Crepidotaceae (Imai) Singer (Basidiomycetes: Agaricales) represents a proposed family of saprophytic fungi containing five agaricoid (Crepidotus, Tubaria, Melanomphalia, Simocybe, Pleurotellus) and four cyphelloid (Episphaeria, Phaeosolenia, Pellidiscus, Chromocyphella) genera. Several contemporary classification systems exist that delegate some or all of these genera to other agaric families. Phylogenetic relationships for the most prevalent genera in the Crepidotaceae were investigated using nuclear large subunit ribosomal DNA (LSU rDNA) sequences. Parsimony analysis of the molecular data supports the Singer classification of Crepidotus, Melanomphalia, and Simocybe as a single monophyletic unit within the Agaricales. The affinities of the genus Tubaria remain uncertain.

Crepidotus (Fr.) Staude is the largest and most phenotypically variable genus in the Crepidotaceae. Sequencing of the LSU rDNA region for a cross-section of morphologically diverse species suggests that Crepidotus is not a monophyletic genus. Analysis of morphological characters for 23 Crepidotus taxa shows that characters traditionally applied for infrageneric classification of Crepidotus are homoplasic in origin, but that less commonly emphasized characters such as spore shape and ultrastructure of spore wall ornamentation may be indicative of monophyletic clades for this complex.

A unique pattern of basidiospore dormancy and germination, unknown in any other species of agaric, is reported for 11 species of Crepidotus. Similar patterns were also encountered in species of Simocybe and Melanomphalia. In these species an endogenous period of spore dormancy of four to six months is followed by an activation period where the factors necessary for subsequent germination appear to involve a minimal nutritional component, water, and exposure to light.

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