Three new species in Russula subsection Xerampelinae supported by genealogical and phenotypic coherence

ABSTRACT

Xerampelinae is a subsection composed of species of ectomycorrhizal fungi belonging to the hyperdiverse and cosmopolitan genus Russula (Russulales). Species of Xerampelinae are recognized by their fishy or shrimp odor, browning context, and a green reaction to iron sulfate. However, species delimitation has traditionally relied on morphology and analysis of limited molecular data. Prior taxonomic work in Xerampelinae has led to the description of as many as 59 taxa in Europe and 19 in North America. Here we provide the first multilocus phylogeny of European and North American members based on two nrDNA loci and two protein-coding genes. The resulting phylogeny supports the recognition of 17 species-rank Xerampelinae clades; however, higher species richness (~23) is suggested by a more inclusive nuclear rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS barcode) analysis. Phylogenetic and morphological analyses support three new species with restricted geographic distributions: R. lapponica, R. neopascua, and R. olympiana. We confirm that the European species R. subrubens is present in North America and the North American species R. serissima (previously known as R. favrei) is present in Europe. Most other Xerampelinae appear restricted to either North America or Eurasia, which indicates a high degree of regional endemism; this includes R. xerampelina, a name widely applied to North American taxa, but a species restricted to Eurasia.

KEYWORDS:

• Ectomycorrhizal
• fungi
• morphology
• phylogeny
• rpb2
• taxonomy
• tef1
• 28S
• 3 new taxa

ACKNOWLEDGMENTS

Cathy L. Cripps (CLC) is acknowledged for collecting some of the R. neopascua and R. clavipes samples. Jeannette Barreca collected specimens of R. olympiana, including the holotype. Karen Golinski, Spencer Goyette, and Olivia Lee helped to initiate loans of R. olympiana.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

SUPPLEMENTARY MATERIAL

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00275514.2023.2295957

Additional information

Funding

The laboratory work of the Slovak team was funded by Slovak national projects APVV 20-0257 and APVV 20-0284 and VEGA 2/0050/22. Chance R. Noffsinger and P. Brandon Matheny were supported by awards from the U.S. National Science Foundation (DEB-2030779) and the Tennessee Herbarium Hesler Endowment Fund. Mary L. Berbee acknowledges funding from Natural Sciences and Engineering Research Council of Canada Discovery Grant RGPIN-2022-03813.