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We present the first phylogenetic evaluation of the genus Dermoloma, which is resolved as monophyletic and closely related to Pseudotricholoma, a poorly known Dermoloma-like lineage within the family Tricholomataceae. The position of Dermoloma is confirmed by the placement of the type species, Dermoloma cuneifolium, represented by multiple samples including the neotype. Based on our phylogenetic analyses, we recognised 25 European operational taxonomic units (OTUs) but could only assign species names to ten of them based on ex-type sequences. Furthermore, only five additional published Dermoloma names of uncertain status are available for the remaining 16 potential European species, thus demonstrating an unexpected amount of taxonomic diversity. Samples from Europe and North America seem to be endemic on a continental scale. North American samples formed six unique OTUs, but only one could be reliably named, Dermoloma hymenocephalum. Dermoloma is morphologically defined by basidiomata with brown, grey and white colours with a farinaceous odour and a pluristratous hymeniderm type of pileipellis. Our phylogenetic analyses support the subdivision of the genus into two subgenera and four sections, and species with inamyloid basidiospores are placed in subg. Dermoloma and those with amyloid basidiospores in subg. Amylospora. Both subgenera are further divided into two sections. The analysis of spore morphology shows that sect. Conica of subg. Dermoloma and sect. Nigrescentia of subg. Amylospora have a very distinctive spore shape. Sect. Atrobrunnea of subg. Amylospora showed relatively high variability of spores among species, but spores of sect. Dermoloma were similar and not useful for species discrimination.

The study deals with the last unexplored morphological group of the genus Hodophilus defined by absence of distinct odours, absence of yellow colours and absence of darker dots on the stipe. The phylogenetic reconstruction of the whole genus based on nrITS, nrLSU and RPB2 sequences placed all European members having these morphological characters in a monophyletic group defined here as a new section H. sect. Phaeophylli. The remaining European members of the genus are placed in two additional groups classified as section H. sect. Hodophilus and the new section H. sect. Micacei. Five species are recognised within section Phaeophylli which is typified by H. phaeophyllus that is lecto- and epitypified. Three new species belonging to this section are described: H. carpathicus, H. decurrentior and H. stramineus. Hodophilus decurrentior is the only species showing distinct morphological differences under the microscope. The identification of other species of the section depends mainly on the colour of basidiomata. An updated key to all European members of the genus is provided.

Phylogenetic reconstruction of Hodophilus species with a yellow colour on the stipe based on nrITS, nrLSU and rpb2 sequences revealed six European species. All these species correspond to the widely accepted European concept of a single species Hodophilus micaceus. Four of these species are described and illustrated. H. micaceus and H. phaeoxanthus are recognised as two separate species and H. albofloccipes as a synonym of the latter. Two species, H. anatinus and H. cambriensis, are described as new. Possible endemism of H. micaceus and H. cambriensis to the British Isles is discussed. All analysed North American samples represent different species to those found in Europe. The North American species Hygrophorus rugulosus is combined in the genus Hodophilus. The preliminary key uses position and development of the yellow colour during maturation as the most important distinguishing character. The presence of the yellow colour is discussed as a possible synapomorphic character.

Russula is one of the most speciose genera of mushroom-forming fungi, but phylogenetic relationships among species and subgeneric groupings are poorly understood. Our multi-locus phylogenetic reconstruction places R. firmula, R. rubra, R. rutila and R. veternosa in a well-supported Rubrinae clade, belonging to the Integrae clade of the Crown clade of the genus Russula. Traditional morphology-based classifications placed these four species in two different subsections based on the presence or absence of incrustations on pileocystidia. The Integrae clade also contains R. integra and related species that are traditionally placed in other groups based on their mild taste. Ancestral state reconstruction suggests that the common ancestor of the Crown clade and the Integrae clade probably did not have any incrustations in the pileipellis, had a mild taste, yellow spore print and were associated with angiosperms. All four species of the Rubrinae clade are defined by a darker yellow or ochre spore print, acrid taste and incrustations on pileocystidia. This last character contradicts the former splitting of the group because incrustations were apparently overlooked in R. firmula and R. veternosa. Incrustation type is now highlighted as being important for the delimitation of species and groups within the Crown clade. Pink or red staining of the incrustations in sulphovanillin is present in all species of the Rubrinae clade and a majority of the analysed species of the Integrae clade. The delimitation of the Rubrinae clade and its species circumscriptions are summarised here in a new diagnostic key.

Hodophilus atropunctus is traditionally defined as the only species of this genus with dark brown or black dots on the stipe. Multi-locus phylogenetic reconstruction recognised two distinct clades morphologically corresponding to this species concept. The limited morphological description in the protologue of H. atropunctus and absence of a type specimen were limitations in an assignment of this name to one of the recognised phylogenetic species. The emended species concept and the selection of a neotype are based on careful analyses of the colour of the basidiomata and how this changes during maturation and drying. The name H. atropunctus is assigned to the paler of the two species which also shows colour change across the pileus and along the length of the stipe when dry. The second darker species is described here as new, H. variabilipes, but only seven out of 14 collections examined belonging to this taxon had distinct dark coloured dots on the stipe surface.

Four European Hodophilus species with an odour similar to naphthalene, a strong unpleasant odour similar to that of mothballs, are recognized based on sequence and/or morphological data. The traditional concept defines Ho. foetens as the only Hodophilus species with a naphthalene odour in Europe. This name is now assigned to one of the studied species based on morphological examination of the holotype specimen. A recently collected specimen is proposed as the epitype. The other three species with a naphthalene odour are described here as new: Ho. pallidus, Ho. subfoetens and Ho. tenuicystidiatus. They are distinguishable in the field based on a combination of lamellae number and colour of basidiomata. All four species are grouped in the Ho. foetens superclade, one of two superclades, together with the Ho. micaceus superclade, in the genus Hodophilus. All are different species from North American taxa with a naphthalene-like odour recognised in a previous study. The Ho. foetens superclade also includes one species identified as Ho. atropunctus that does not have a distinctive odour. The type collection of Ho. albofloccipes, a recently described European species with a naphthalene odour, is placed together with some collections without a distinctive odour in the Ho. micaceus superclade.

Melanoleuca brevipes (basionym Agaricus brevipes) represents one of the most frequently identified Melanoleuca species. However, there are several concepts of this taxon, and thus the identity of this species is unclear. This species was studied, based on the original table by Bulliard, macromorphological and micromorphological characters, and DNA sequences of recent collections and herbarium specimens. DNA sequences of ITS, RPB2 and tef1 markers revealed that specimens identified as M. brevipes belong to three species (M. humilis, M. grammopodia, and M. malenconii), where M. humilis or M. malenconii may resemble Bulliard’s original species. According to these results, Agaricus brevipes is therefore considered a nomen dubium. A lectotype of M. grammopodia is proposed herein.