The enigmatic Mixia osmundae revisited: a systematic review including new distributional data and recent advances in its phylogeny and phylogenomics

ABSTRACT

The enigmatic basidiomycete genus Mixia includes intracellular parasites of Osmunda and Osmundastrum ferns. Here, the authors review the systematic and phylogenetic history of M. osmundae, originally known as Taphrina osmundae, and provide new data from investigations of specimens of Osmunda japonica collected in Yunnan Province, China, which we determine to be conspecific with M. osmundae. In addition, Taphrina higginsii, a parasite on fronds of Osmundastrum cinnamomeum described from Georgia, USA, was confirmed to be phenotypically identical with M. osmundae. The name T. higginsii is lectotypified with a Mix specimen. Collections examined to date document four localities for M. osmundae: Japan (Honshu and Kyushu), Taiwan (Taichung), USA (Georgia), and China (Yunnan), and host-parasite relationships with the old extant ferns Osmunda japonica and its relatives and with Osmundastrum cinnamomeum. The phylogenetic placement of M. osmundae on the fungal tree of life, its evolutionary implications, and recent advances in the phylogenomics of this fungus are briefly reviewed and discussed.

KEYWORDS:

• Evolution
• Mixiomycetes
• molecular phylogenetics
• Osmunda
• Osmundastrum
• phylogenomics
• Saitoella
• Taphrina

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Corrigendum

ACKNOWLEDGMENTS

This paper is a contribution to a special issue of Mycologia honoring Professor Meredith Blackwell and her career. J.S. is grateful for her friendly eyes and continuous friendship since they met in Newport, Oregon, at the Holomorph Conference organized by Dr. Don Reynolds and Dr. John W. Taylor held at the Shilo Inn August 4–6, 1991. The loan of Taphrina higginsii specimens was kindly arranged by the Curator and Ms. Lucy Klebieko, William and Lynda Steere Herbarium, New York Botanical Garden Herbarium (NY), with the assistance of Dr. Scott Redhead (DAOM) in Ottawa, Canada. We thank Dr. Pedro Crous, director of Westerdijk Fungal Biodiversity Institute (copyright holder) for his courtesy and Dr. F.-Y. Bai and Dr. Teun Boekhout (co-corresponding authors) for the reproduction of their Figure 1 with some modifications. Finally, we are grateful to Dr. Joey Spatafora for his kind invitation to this special issue, and we also thank Guest Editor Dr. Cathie Aime, Executive Editor Dr. Keith Seifert, and two anonymous reviewers for their insightful comments and help, which considerably improved the manuscript.