Revision of pyrophilous taxa of Pholiota described from North America reveals four species—P. brunnescens, P. castanea, P. highlandensis, and P. molesta

ABSTRACT

A systematic reevaluation of North American pyrophilous or “burn-loving” species of Pholiota is presented based on molecular and morphological examination of type and historical collections. Confusion surrounds application of the names P. brunnescens, P. carbonaria, P. castanea, P. fulvozonata, P. highlandensis, P. molesta, and P. subsaponacea, with multiple names applied to a single species and multiple species described more than once. Molecular annotations using nuc rDNA ITS1-5.8S-ITS2 (internal transcribed spacer [ITS] barcode) and RPB2 (RNA polymerase II second largest subunit) are used to aid in application of these names in a phylogenetic context. Based on ITS molecular annotations of 13 types, the following heterotypic synonymies are proposed: P. highlandensis (syn. P. carbonaria and P. fulvozonata); P. molesta (syn. P. subsaponacea); and P. brunnescens (syn. P. luteobadia). In addition, we observed that the species P. castanea, known previously only from the type collection in Tennessee, is found commonly on burned sites near the Gulf Coast and other southeast regions of the United States. Overall, the pyrophilous trait is evolutionarily derived in Pholiota. Endophytic and endolichenic stages were deduced for P. highlandensis, the most widely distributed of the pyrophilous Pholiota. As a result, we introduce the “body snatchers” hypothesis that explains the maintenance of some pyrophilous fungi in ecosystems as endophytes and/or endolichenic fungi. Photographs, taxonomic descriptions, and a dichotomous key to pyrophilous species of Pholiota that occur in North America are presented.

KEYWORDS:

• Agaricales
• fire ecology
• Strophariaceae
• systematics
• taxonomy
• type collections

ACKNOWLEDGMENTS

We thank Pat Rogers and Tim James at MICH, Joe Ammirati, David Giblin, and staff at WTU, Heino Lepp at CANB, Dale Kruse at TAES, and Lorinda Leonardi at NYS for assistance with loans, and Paul Super, Science Coordinator at the Great Smoky Mountains National Park, for collection permit GRSM-2017-SCI-1294. Alicia Hobbs and Alexis Case provided laboratory support at the University of Tennessee. David Lewis provided collection information and photographs of Pholiota castanea. We thank Steve Trudell and Mike Wood for sharing photographs of Pholiota brunnescens and P. molesta. Teresa Iturriaga, Jacob Kalichman, and Daniel Raudabaugh provided field support.

Additional information

Funding

This work was supported by a National Science Foundation awards (DEB-1733750 and DEB-1733854, Collaborative Research: “A survey of post-fire ascomycete and basidiomycete fungi in an eastern deciduous forest”) to K.W.H., R.H.P., P.B.M., and A.N.M. and an award to P.B.M. from the Hesler Endowment Fund at the University of Tennessee.