Molecular inference, multivariate morphometrics and ecological assessment are applied in concert to delimit species in the Russula clavipes complex

Abstract

Species of Russula subsect. Xerampelinae are notoriously difficult to identify and name and have not been subject to molecular study. A group of species, referred to here as the R. clavipes complex, growing in association with Salix, Betula and Populus as well as coniferous tree species from temperate to arctic and alpine habitats, were examined. Analyses of the nuc rDNA internal transcribed spacer (ITS) region and a numerical analysis of morphological characters were used. The R. clavipes complex is a monophyletic group within Russula subsect. Xerampelinae, according to molecular results. The complex includes three species: R. nuoljae is a phylogenetically and morphologically well-supported species while the other two, R. clavipes and R. pascua, are similar based on ITS data and morphology but separate based on their ecology. Russula pseudoolivascens is conspecific with R. clavipes. Several combinations of characters traditionally used in the taxonomy of R. subsect. Xerampelinae are inappropriate for species delimitation in this group and the adequacy of the ITS for species identification in this group is discussed. Detailed microscopic observations on the type collection of R. nuoljae are presented and illustrated, along with a key to the European members of R. subsect. Xerampelinae.

• DNA barcode
• ectomycorrhizal fungi
• Europe
• haplotype analysis
• Russula nuoljae
• R. pascua

Acknowledgments

The authors thank herbaria C, FR, G, IB, L and KR for the loan of collections for study and sequencing and the staff of KRAM, SAV, STU, TU, TUB and UPS for handling submissions. U. Eberhardt thanks the Alpine Research Center Finse, the Abisko Research Station and E. and V. Emmett for their hospitality. Furthermore, we very much appreciated the help of E. Eberhardt, E. Emmett, A.F.S. Taylor, J. Vesterholt, B. Wasstorp and other collectors we may have forgotten by accident for supplying us with interesting and exciting collections. The studies of S. Adamčík and M. Slovák were supported by the Slovak national project VEGA 02/0075/14. The work of U. Eberhardt at SLU Uppsala was supported by a grant from the Swedish Species Project. The field work in the alpine belt of the Carpathians and part of the laboratory work was supported by the statutory fund of the W. Szafer Institute of Botany of the Polish Academy of Sciences, the Polish Ministry of Science and Higher Education and Polish National Science Center (projects 2 P04C 086 30 and N N303 308237) and by the exchange program between Polish and Slovak Academies of Sciences.