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.

Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.

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Nivicolous myxomycetes constitute an ecologically well defined group of organisms occurring at the edge of melting winter snow cover. They often are considered and described as alpine species, occurring exclusively or most frequently in the alpine belt. We reviewed and synthesized available published data on the altitudinal occurrences of nivicolous myxomycetes in 22 massifs worldwide and attributed the records to main altitudinal belts (montane/subalpine/alpine) defined for particular areas. Based on this comparative analysis we attempted to analyze and discuss general views on the altitudinal/biogeographical properties of nivicolous myxomycetes. Our study indicates that the altitudinal distribution of nivicolous mycomycetes extends over montane, subalpine and alpine belts. The most abundant records were found in the forest (montane) belt, while the alpine belt had the lowest number of occurrences. Although this picture might be biased to some extent by better average exploration of lower areas, it shows clearly that this ecological group-even though connected with mountainous habitats-does not form an alpine element. Therefore they should not be considered alpine species. Based on the available data it also could be hypothesized that nivicolous myxomycetes form a widely distributed biogeographical mountain element instead of an alpine or arctic-alpine element. Based on our conclusions we also emphasize the need for precise and cautious use of the notion of "alpines", which appears to be confusingly overused in the myxomycete studies.