The Russula globispora lineage is a morphologically and phylogenetically well-defined group of ectomycorrhizal fungi occurring in various climatic areas. In this study we performed a multi-locus phylogenetic study based on collections from boreal, alpine and arctic habitats of Europe and Western North America, subalpine collections from the southeast Himalayas and collections from subtropical coniferous forests of Pakistan. European and North American collections are nearly identical and probably represent a single species named R. dryadicola distributed from the Alps to the Rocky Mountains. Collections from the southeast Himalayas belong to two distinct species: R. abbottabadensis sp. nov. from subtropical monodominant forests of Pinus roxburghii and R. tengii sp. nov. from subalpine mixed forests of Abies and Betula. The results suggest that speciation in this group is driven by a climate disjunction and adaptation rather than a host switch and geographical distance.

Dermoloma is traditionally known as a small genus of agarics classified in the family Tricholomataceae. This study implemented a multilocus phylogeny of six DNA regions to recognize phylogenetic species within the genus. The species concept is reinforced by observations of well-defined morphological characters enhanced by long term sampling effort in Europe and North America. Thirty European Dermoloma species are described, including 16 new species from Europe and three from North American. These species are classified into two subgenera morphologically distinguished by spores with positive or negative amyloid reaction. A new genus Neodermoloma is introduced for the Dermoloma-like species N. campestre. Localized or continental-scale species endemicity was confirmed based on studied material, but more inclusive phylogenetic clustering supported a mixture of North American species among the European clades. Of the 22 names validly published from Europe prior to this study, 11 could be assigned to well-defined Dermoloma species recognized here. Of the remaining 11 names, two were considered representing Dermoloma species not recorded since their description, and nine were established as later synonyms of other species. Morphological studies of Dermoloma are challenging due to the relatively low number of characters suitable for identification of species. The majority of morphological characters showed continuous variation with high overlap throughout the genus. For this reason, species identification requires an awareness of morphological variability within species, and multiple distinguishing characters need to be combined, and furthermore, often a barcode sequence is needed for a certain identification. Stable isotope analysis in Dermoloma of δ¹³C and δ¹⁵N revealed an ecological signature similar to known CHEGD fungi, i.e. Clavariaceae and Hygrocybe s.l. This indicates that Dermoloma species are biotrophic but neither ectomycorrhizal nor saprotrophic and may form mutualistic root endophytic associations with vascular plants.

In this paper, the authors present modern microscopical studies for 28 type specimens of Russula species described by C.H. Peck, thereby completing the revision of all 44 Russula taxa described by this author and for which type specimens were available. Our results suggest that with eventual exception of R. granulata var. lepiotoides (a likely synonym of the type variety) and R. magnifica (a likely synonym of R. polyphylla), all other Russulas described by Peck correspond to well-defined North American taxa. Having been described more than one century ago, Peck's names represent the majority of the earliest described North American Russula species and our type revisions are therefore important both for nomenclatural aspects, as well as typification and identification purposes. All studied taxa are illustrated in detail and accompanied by notes including a short recapitulation of previous type revisions, as well as our own re-evalutation of their systematic position as a result of this study.

The current generally accepted concept of Russula maculata defines the species by yellow-brownish spots on the basidiomata, an acrid taste, a yellow spore print and a red pileus. This concept was tested using collections originating from various geographical areas mainly in Europe. Analyses of the ITS region suggested that there were three species within this broad concept. One of them, R. maculata, was identified based on the sequence from the epitype. Two other species, R. nympharum and R. sp., are described here as newly identified species. The European species R. maculata and R. nympharum grow in deciduous forests, are similar in their field aspect and are distinctly different in micro-morphological characteristics of spores, pleurocystidia and pileipellis. An Asian species, R. sp., is associated with pine and has smaller basidiomata and spores. These three species form the R. maculata complex and represent the sister clade to the R. globispora complex. This clade consists of species also characterized by a yellow-brownish context discolouration but with a different type of spore ornamentation. All of the other tested species had an acrid taste and yellow spore print but did not have a conspicuous yellow-brownish context discolouration and were placed in various unrelated clades.