Stop black and white thinking: Russula subgenus Compactae (Russulaceae, Russulales) in Europe revised.

Russula subgenus Compactae is a group of ectomycorrhizal basidiomycetes, usually with large pileate fruitbodies. European members of the group are characterised by the absence of bright colours on the surfaces of their pilei, the context turning grey to black after cutting, the abundance of short lamellulae in the hymenophore, and spores with an inamyloid suprahilar spot and with low reticulate ornamentation. Our multi-locus phylogenetic study confirmed that this morphological delimitation corresponds to a well-supported clade. Within this clade, 16 species are recognised in Europe, of which five belong to the R. albonigra lineage and were described in a previous study, while eleven are fully described in this study. The application of the names R. acrifolia, R. adusta, R. anthracina, R. atramentosa, R. densissima, R. nigricans and R. roseonigra is based on the position of sequences retrieved from types or authentic material. Based on type sequences, R. fuliginosa is synonymised with R. anthracina and two varieties of R. anthracina are considered synonyms of R. atramentosa. The application of the name R. densifolia is based on a morphological match with the traditional species interpretation and the neotype specimen. Three species are described as new, R. marxmuelleriana sp. nov., R. picrophylla sp. nov. and R. thuringiaca sp. nov. This study recognises three major lineages and two species with isolated positions within the European Compactae and a morphological barcode was assigned to the species using an analysis of 23 selected characters. A search of publicly available sequences from the UNITE database revealed that the majority of species are host tree generalists and widely distributed in temperate and Mediterranean areas of Europe. Russula adusta is the only species so far proven to form ectomycorrhiza exclusively with conifers. Citation: De Lange R, Kleine J, Hampe F, et al. 2023. Stop black and white thinking: Russula subgenus Compactae (Russulaceae, Russulales) in Europe revised. Persoonia 51: 152-193. doi: 10.3767/persoonia.2023.51.04.

A short story of nearly everything in Lactifluus (Russulaceae).

Fungi are a large and hyper-diverse group with major taxa present in every ecosystem on earth. However, compared to other eukaryotic organisms, their diversity is largely understudied. Since the rise of molecular techniques, new lineages are being discovered at an increasing rate, but many are not accurately characterised. Access to comprehensive and reliable taxonomic information of organisms is fundamental for research in different disciplines exploring a variety of questions. A globally dominant ectomycorrhizal (ECM) fungal family in terrestrial ecosystems is the Russulaceae (Russulales, Basidiomycota) family. Amongst the mainly agaricoid Russulaceae genera, the ectomycorrhizal genus Lactifluus was historically least studied due to its largely tropical distribution in many underexplored areas and the apparent occurrence of several species complexes. Due to increased studies in the tropics, with a focus on this genus, knowledge on Lactifluus grew. We demonstrate here that Lactifluus is now one of the best-known ECM genera. This paper aims to provide a thorough overview of the current knowledge of Lactifluus, with information on diversity, distribution, ecology, phylogeny, taxonomy, morphology, and ethnomycological uses of species in this genus. This is a result of our larger study, aimed at building a comprehensive and complete dataset or taxonomic framework for Lactifluus, based on molecular, morphological, biogeographical, and taxonomical data as a tool and reference for other researchers. Citation: De Crop E, Delgat L, Nuytinck J, Halling RE, Verbeken A (2021). A short story of nearly everything in Lactifluus (Russulaceae). Fungal Systematics and Evolution 7: 133-164. doi: 10.3114/fuse.2021.07.07.

Lactifluus (Russulaceae) diversity in Central America and the Caribbean: melting pot between realms.

Species of the ectomycorrhizal genus Lactifluus, and often entire sections, are typically unique to a single continent. Given these biogeographic patterns, an interesting region to study their diversity is Central America and the Caribbean, since the region is closely connected to and often considered a part of the North American continent, but biogeographically belong to the Neotropical realm, and comprises several regions with different geologic histories. Based on a multi-gene phylogeny and morphological study, this study shows that Central America, Mexico and the Caribbean harbour at least 35 Lactifluus species, of which 33 were never reported outside of this region. It was found that species from the Caribbean generally show affinities to South American taxa, while species from the Central American mainland generally show affinities to Northern hemispheric taxa. We hypothesise that host specificity and/or climate play a crucial role in these different origins of diversity. Because of these different affinities, Caribbean islands harbour a completely different Lactifluus diversity than the Central American mainland. The majority of species occurring on the islands can be considered endemic to certain islands or island groups. In this paper, detailed morphological descriptions are given, with a focus on the unique diversity of the islands, and identification keys to all hitherto described Lactifluus species occurring in Central America and the Caribbean are provided. One new section, Lactifluus sect. Nebulosi, and three new species, Lactifluus guadeloupensis, Lactifluus lepus and Lactifluus marmoratus are described.

A multi-gene phylogeny of Lactifluus (Basidiomycota, Russulales) translated into a new infrageneric classification of the genus.

Infrageneric relations of the genetically diverse milkcap genus Lactifluus (Russulales, Basidiomycota) are poorly known. Currently used classification systems still largely reflect the traditional, mainly morphological, characters used for infrageneric delimitations of milkcaps. Increased sampling, combined with small-scale molecular studies, show that this genus is underexplored and in need of revision. For this study, we assembled an extensive dataset of the genus Lactifluus, comprising 80 % of all known species and 30 % of the type collections. To unravel the infrageneric relationships within this genus, we combined a multi-gene molecular phylogeny, based on nuclear ITS, LSU, RPB2 and RPB1, with a morphological study, focussing on five important characteristics (fruit body type, presence of a secondary velum, colour reaction of the latex/context, pileipellis type and presence of true cystidia). Lactifluus comprises four supported subgenera, each containing several supported clades. With extensive sampling, ten new clades and at least 17 new species were discovered, which highlight the high diversity in this genus. The traditional infrageneric classification is only partly maintained and nomenclatural changes are proposed. Our morphological study shows that the five featured characteristics are important at different evolutionary levels, but further characteristics need to be studied to find morphological support for each clade. This study paves the way for a more detailed investigation of biogeographical history and character evolution within Lactifluus.