A Morphological and Molecular Reassessment of Robergea albicedrae (Ascomycota)

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.