A phylogenetic assessment of Pholiota and the new genus Pyrrhulomyces

ABSTRACT

Multigene data sets were assembled to evaluate the phylogeny of species attributed to the genus Pholiota sensu A.H. Sm. & Hesler. This effort included generation of just more than 200 new sequences from 19 type collections of Pholiota and recent samples from East Asia. Phylogenetic analyses reinforced the autonomous phylogenetic positions of pholiotoid taxa in the genera Flammula (Hymenogastraceae) and Kuehneromyces (Strophariaceae). Samples of Pholiota astragalina from diverse geographic regions split into two species-level lineages but occupied an isolated phylogenetic position apart from Pholiota sensu stricto. The new genus Pyrrhulomyces is described to accommodate P. astragalina and a new cryptic species from the Southern Appalachians, Pyrrhulomyces amariceps. Pyrrhulomyces is distinguished from other genera of Strophariaceae by the blackening basidiomata with a bitter taste, smooth basidiospores without a germ pore under light microscopy, presence of pleurochrysocystidia, an ixocutis, rugulose spore ornamentation under scanning electron microscope (SEM), and association with late stages of conifer wood decay. Pholiota subochracea was found to be sister to a clade containing samples of Hypholoma and Bogbodia, but this portion of the Strophariaceae will require further taxon and gene sampling to resolve relationships between these three taxa. Pholiota sensu stricto comprised at least two major groups, but several residual poorly placed lineages were also noted depending on the data set analyzed. New combinations are made in the genera Flammula, Kuehneromyces, and Stropharia for three species of Pholiota—P. abieticola, P. obscura, and P. scabella, respectively, based on molecular annotation of type collections. Overall, 20 new synonymies are proposed, mostly in Pholiota. Illustrations of Pyrrhulomyces are provided along with a key to genera of Strophariaceae and Hymenogastraceae.

KEYWORDS:

• Agaricales
• morphology
• phylogeny
• Strophariaceae
• systematics
• taxonomy
• 6 new taxa

ACKNOWLEDGMENTS

We thank Aaron Wolfenbarger, Jean Lodge, Rachel Swenie, and Jacob Kalichman for their participation and assistance. Matt Gordon kindly shared the ITS sequence of the holotype of Pholiota scabella. We thank Mike Wood and Rachel Swenie for sharing photographs. Viki Ramírez-Cruz provided helpful discussion about the key. Else Vellinga is acknowledged for her suggestion of the generic name Pyrrhulomyces. The authors also thank two anonymous reviewers and executive editor Priscila Chavarri for their constructive comments.

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Funding

This research was supported by the National Key Research and Development program of China (2019YFC1604703) and China Scholarship Council and funds for a Visiting Scholar Fellowship from the Hesler Endowment Fund administered by the University of Tennessee Herbarium and Department of Ecology and Evolutionary Biology.