Since 2007, the quality of Russula descriptions has improved and the use of molecular support for species delimitation and the number of published new species has increased. However, the description style is not consistent and has regional or author-specific patterns. Most recent publications still favour descriptions of spores compared to hymenium and pileipellis elements, and usually only the spore size is provided with statistical support. This study proposes standards for descriptions of the microscopic structure of Russula species (Russulaceae, Agaricomycetes). We present the description template, the template measurements table, the specific terminology and the essential chemical reagents. The proposed standards were tested by mycologists from 11 countries who met at the Russula Microscopy Workshop in Slovakia. Descriptions of 26 species from 9 countries and four continents were prepared, among them R. amarissima, R. castanopsidis, R. seperina and R. subtilis are re-described and 15 species are introduced as new: R. abietiphila, R. amerorecondita, R. aurantioflava, R. echidna, R. flavobrunnescens, R. fluvialis, R. fortunae, R. garyensis, R. gemmata, R. laevis, R. madrensis, R. olivaceohimalayensis, R. purpureogracilis, R. sancti-pauli and R. wielangtae. Seven descriptions for candidate new species are provided without a formal name assignment. Pairwise comparison of species described in this study with available similar descriptions of related species suggests that microscopic characters from all parts of the basidiomata can be equally important for species recognition and they deserve the same treatment including number of measurements and statistics. The majority of recent studies does not recognise differences between the pileus margin and centre, but more than one-third of the species described in this study show distinct differences between the pileus areas, emphasizing the importance to specify the origin of pileipellis observations. This study proved that there is frequently insufficient difference in the ITS barcode between closely related species and that it is necessary to use more genetic markers combined with ecological and geographical data.

The diversity within the ectomycorrhizal genus Russula (Basidiomycota) in West Africa is largely unexplored. The study area was Benin, where only ten out of the 159 species endemic to tropical Africa have been previously reported. We focused on “Afrovirescentinae”, which is a monophyletic lineage within Russula subgen. Heterophyllidiae sister to subsect. Virescentinae. The phylogenetic placement of this clade was analysed using sequence data from ITS, LSU, mtSSU, tef1, rpb1 and rpb2 regions. Ten “Afrovirescentinae” species are recognised, described and illustrated from Benin. Four of them, R. carmesina, R. hiemisilvae, R. inflata and R. sublaevis, were previously published. Five species, Russula acrialbidasp. nov., R. beenkeniisp. nov., R. coronatasp. nov., R. floraesp. nov. and R. spectabilissp. nov., are newly described. Species within this group are characterised by densely reticulated spore ornamentation, but they exhibit considerable variation in field appearance and pileipellis structure. In gallery forests, their basidiomata are ephemeral, small and their basidiospores have prominent ornamentation; while in savannah woodlands, the basidiomata are fleshy, large and basidiospores present low ornamentation. We suggest that these morphological traits may represent evolutionary adaptations to a specific environmental condition. We analysed the species richness, ecological range and distribution of the “Afrovirescentinae” clade globally based on data from the UNITE database, estimating a total diversity of 94 species primarily distributed in sub-Saharan Africa, but also in the Neotropics. Four additional previously described species not detected in Benin were assigned to this clade, based on holotype sequencing. Several species are widely distributed across tropical Africa and do not show specificity regarding their associated plant symbionts.

The authors describe ten new taxa for science using mostly both morphological and molecular data. In Ascomycota, descriptions are provided for Bambusistroma didymosporum gen. et spec. nov. (Pleosporales), Neodeightonia licuriensis sp. nov. (Botryosphaeriales) and Camposporium himalayanum sp. nov. (Fungi imperfecti). In Zygomycota, Gongronella guangdongensis sp. nov. (Mucorales) is described. Finally, in Basidiomycota descriptions are provided for Boidinia parva sp. nov. and Russula katarinae sp. nov. (Russsulales), Gloiocephala parvinelumbonifolia sp. nov. (Agaricales), Hypochnicium austrosinensis sp. nov. (Polyporales), Phallus ultraduplicatus sp. nov. (Phallales) and Suillus lariciphilus sp. nov. (Boletales).

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.