Reappraisal of the Genus Exsudoporus (Boletaceae) Worldwide Based on Multi-Gene Phylogeny, Morphology and Biogeography, and Insights on Amoenoboletus.

The boletoid genera Butyriboletus and Exsudoporus have recently been suggested by some researchers to constitute a single genus, and Exsudoporus was merged into Butyriboletus as a later synonym. However, no convincing arguments have yet provided significant evidence for this congeneric placement. In this study, we analyze material from Exsudoporus species and closely related taxa to assess taxonomic and phylogenetic boundaries between these genera and to clarify species delimitation within Exsudoporus. Outcomes from a multilocus phylogenetic analysis (ITS, nrLSU, tef1-α and rpb2) clearly resolve Exsudoporus as a monophyletic, homogenous and independent genus that is sister to Butyriboletus. An accurate morphological description, comprehensive sampling, type studies, line drawings and a historical overview on the nomenclatural issues of the type species E. permagnificus are provided. Furthermore, this species is documented for the first time from Israel in association with Quercus calliprinos. The previously described North American species Exsudoporus frostii and E. floridanus are molecularly confirmed as representatives of Exsudoporus, and E. floridanus is epitypified. The eastern Asian species Leccinum rubrum is assigned here to Exsudoporus based on molecular evidence, and a new combination is proposed. Sequence data from the original material of the Japanese Boletus kermesinus were generated, and its conspecificity with L. rubrum is inferred as formerly presumed based on morphology. Four additional cryptic species from North and Central America previously misdetermined as either B. frostii or B. floridanus are phylogenetically placed but remain undescribed due to the paucity of available material. Boletus weberi (syn. B. pseudofrostii) and Xerocomus cf. mcrobbii cluster outside of Exsudoporus and are herein assigned to the recently described genus Amoenoboletus. Biogeographic distribution patterns are elucidated, and a dichotomous key to all known species of Exsudoporus worldwide is presented.

Funder

Funder name	Awards
University of Haifa, Israel
Mycological Society of Israel
National Science Foundation, United States	Grant DEB-2106130
Institute of Food and Agricultural Sciences, University of Florida, United States
Florida Agricultural Experiment Station, United States	Ordway-Swisher research grant
National Institute of Food and Agriculture, United States	Hatch 1001991 - McIntire-Stennis 1011527

Journal title

Journal of Fungi

Volume

8

Issue

2

Article number

101

Publisher

MDPI AG

Place of publication

Basel, Switzerland

eISSN

2309-608X

Date accepted

January 14, 2022

Official URL

https://doi.org/10.3390/jof8020101

Related URL

https://www.mdpi.com/2309-608X/8/2/101

Rights statement

In Copyright

Licence

https://creativecommons.org/licenses/by/4.0/

DOI

Keywords

Additional information

This article belongs to the Special Issue Biodiversity, Distribution and Conservation of Plants and Fungi; Effects of Global Warming and Environmental Stress.