A Morphological and Molecular Reassessment of Robergea albicedrae (Ascomycota)
Date
2019-12
Authors
Bernardin, Jessica Rae
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Abstract
Historically, ascomycete fungi have been classified based on key morphological
characteristics such as spore size and shape, ascus morphology, and biochemical
indicators. This approach has resulted in groups of organisms that are microscopically
and macroscopically similar, however, in some situations these groupings are not
supported by the results of modern phylogenetic studies. Robergea albicedrae is a
fungus that grows on the bark and twigs of a single species of tree, the Ashe juniper
(Juniperus ashei). First described in 1910, the fungus has been reassigned at the generic
and family levels several times over the past century and is now classified in Stictidaceae.
The goal of this study was to provide new morphological and molecular data to better
understand the life cycle and relationships of the species. Procedures were designed to
culture the fungus both in situ and in vitro. Plastic coverslips were placed on the bark of
Ashe juniper for 17 months in an attempt to document the stages of the life cycle of the
fungus. Samples of Robergea albicedrae were also cultured using a variety of media and
plating techniques. Robergea albicedrae, along with a diversity of other fungi, was
successfully grown on coverslips and in pure culture. Robergea albicedrae was also
sequenced and analyzed at the 18S SSU rDNA and ITS 1 and 2 regions. Analyses of
these sequences using Bayesian phylogenetics provided strong support for the placement
of Robergea albicedrae in the order Ostropales and the family Stictidaceae of the class
Lecanoromycetes.
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Keywords
Fungi, Robergea, Juniperus, Ostropales, Stictidaceae
Citation
Bernardin, J. R. (2019). <i>A morphological and molecular reassessment of Robergea albicedrae (Ascomycota)</i> (Unpublished thesis). Texas State University, San Marcos, Texas.