Meredithblackwellia eburnea gen. et sp. nov., Kriegeriaceae fam. nov. and Kriegeriales ord. nov.—toward resolving higher-level classification in Microbotryomycetes

Abstract

A field survey of ballistosporic yeasts in a Neotropical forest yielded a new species isolated from a fern leaf. The isolate is a cream-colored butyrous yeast that reproduces by budding. Budding occurs at both the apical and basal cell poles; occasionally multiple budding events co-occur, giving rise to rosette-like clusters of cells at both poles of the yeast mother cell. DNA sequences of large and small subunit and the internal transcribed spacer regions of the nuclear ribosomal DNA cistron indicated an affinity to Microbotryomycetes, Pucciniomycotina. A new genus, Meredithblackwellia, is proposed to accommodate the new species, M. eburnea (type strain MCA4105). Based on phylogenetic analyses, Meredithblackwellia is related to Kriegeria eriophori, a sedge parasite, to an aquatic fungus Camptobasidium hydrophilum and to several recently described anamorphic yeasts that have been isolated from plant material or psychrophilic environments. Morphological and ultrastructural studies confirm the relatedness of M. eburnea to these taxa and prompted the re-evaluation of higher-level classification within Microbotryomycetes. We propose here a new order, Kriegeriales, and place two families, Kriegeriaceae fam. nov. and Camptobasidiaceae R.T. Moore, within it. Our study re-emphasizes the need for systematic revision of species described in Rhodotorula.

• basidiomycete yeasts
• fungal taxonomy
• phylloplane
• simple septate basidiomycetes

Acknowledgments

This study was supported by Assembling the Fungal Tree of Life (AFTOL) project NSF DEB-0732968.

We thank Terry Henkel for facilitating long term research in Guyana, Claire Whittaker for general laboratory assistance and Tomas Rush, Sebastian Albu, Gregory Heller and Jorge Diaz for assistance with the assimilation experiments. We are grateful for the help of David Lowry and Ricardo Reyes from the School of Life Sciences Electron Microscope Facility at Arizona State University with TEM and DAPI staining sample preparation and David McLaughlin for his expertise in TEM image interpretation. Anonymous reviewers made useful suggestions on earlier versions of this manuscript, and Else Vellinga provided advice on Latin. This is number 196 in the Smithsonian’s Biological Diversity of the Guiana Shield Program publication series.