Three new species and a new record of Cortinarius section Camphorati from southwestern China.

Cortinarius sect. Camphorati consists of telamonioid species with violet basidioma, strong odor, and distinct cheilocystidia. In this study, phylogenetic analysis based on nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and partial nuc rDNA 28S sequences has revealed three new species of the section from southwestern China, namely, C. longicystidiatus, C. megacystidiatus, and C. paraputorius, and a newly recorded species from southwestern China, viz., C. camphoratus, supplemented by the support from calculations of genetic distances of ITS sequences. Detailed descriptions of the four species are given with photographs, and their micromorphological characteristics are statistically compared. For species delimitation within the section, the size of basidiospores, the morphology of cheilocystidia, and the associated vegetation types and tree species are informative. A key to species in section Camphorati from the Northern Hemisphere is provided, and their geographic distributions and ecology are discussed.

Enlargement of the knowledge of Cortinarius section Anomali (Agaricales, Basidiomycota): introducing three new species from China.

Cortinarius is a globally distributed agaricoid genus that has been well studied in Europe and America with over 1,000 described species. However, as part of an ongoing effort to investigate the diversity of Cortinarius section Anomali in China, the resource investigation and classification research are still limited, and the species diversity has not been clarified by far. During the re-examination of the Chinese Cortinarius specimens, C. cinnamomeolilacinus, C. subclackamasensis, and C. tropicus, belonging to the sect. Anomali, were described in China as new to science based on morphological examination and phylogenetic analysis. The three new species are described and illustrated in detail according to the Chinese materials. The phylogenetic analysis based on internal transcribed spacer sequences confirmed the placement of the three species in the Cortinarius sect. Anomali clade. Phylogenetically related and morphologically similar species to these three new species are discussed.

Purpurascenines A-C, Azepino-Indole Alkaloids from Cortinarius purpurascens: Isolation, Biosynthesis, and Activity Studies on the 5-HT2A Receptor.

Three previously undescribed azepino-indole alkaloids, named purpurascenines A-C (1-3), together with the new-to-nature 7-hydroxytryptophan (4) as well as two known compounds, adenosine (5) and riboflavin (6), were isolated from fruiting bodies of Cortinarius purpurascens Fr. (Cortinariaceae). The structures of 1-3 were elucidated based on spectroscopic analyses and ECD calculations. Furthermore, the biosynthesis of purpurascenine A (1) was investigated by in vivo experiments using 13C-labeled sodium pyruvate, alanine, and sodium acetate incubated with fruiting bodies of C. purpurascens. The incorporation of 13C into 1 was analyzed using 1D NMR and HRESIMS methods. With [3-13C]-pyruvate, a dramatic enrichment of 13C was observed, and hence a biosynthetic route via a direct Pictet-Spengler reaction between α-keto acids and 7-hydroxytryptophan (4) is suggested for the biosynthesis of purpurascenines A-C (1-3). Compound 1 exhibits no antiproliferative or cytotoxic effects against human prostate (PC-3), colorectal (HCT-116), and breast (MCF-7) cancer cells. An in silico docking study confirmed the hypothesis that purpurascenine A (1) could bind to the 5-HT2A serotonin receptor's active site. A new functional 5-HT2A receptor activation assay showed no functional agonistic but some antagonistic effects of 1 against the 5-HT-dependent 5-HT2A activation and likely antagonistic effects on putative constitutive activity of the 5-HT2A receptor.

Old but not obsolete: A new life for some of Murrill's (Hebeloma) names.

William Alphonso Murrill was an American mycologist of the early 20th century. He described 1453 new species of Agaricales, Boletales, and Polyporales. Within these were 44 taxa that he described as Hebeloma or that he recombined into Hebeloma. Additionally, there are five species, of which we are aware, that Murrill described within other genera that should be referred to the genus Hebeloma. A further three species described from northern America by J. P. F. C. Montagne, and transferred to Hebeloma by Saccardo, were commented on by Murrill and not accepted within the genus. These 52 taxa are analyzed here, both morphologically and molecularly, as far as possible. For 18 of his types, internal transcribed spacer (ITS) sequences were generated. For two species (H. harperi and H. subfastibile), which were mixed collections, lectotypes are designated. Twenty-three of the taxa analyzed are Hebeloma, as the genus is recognized today, and six of these (H. australe, H. harperi, H. paludicola, H. subaustrale, H. subfastibile, and H. viscidissimum) are regarded as current, i.e., they are names that should be accepted and used. Hebeloma paludicola is an earlier name for H. hygrophilum, described from Europe. Gymnopilus viscidissimus is synonymous with H. amarellum but has priority and is here recombined into Hebeloma. The remaining 17 Hebeloma taxa are synonymized with other species that have priority. The remaining 29 species belong to a range of genera; molecularly supported were Agrocybe, Cortinarius, Inocybe, Inosperma, Phlegmacium, Pholiota, Pseudosperma, and Pyrrhulomyces. Recombinations and synonymizations are made as appropriate and necessary. The names H. alachuanum and H. vatricosum, respectively Inocybe vatricosa, are considered doubtful and should be avoided.

Photochemical defense as trait of fungi from Cortinarius subgenus Dermocybe.

The photobiological activity of ten colorful species belonging to subgenus Dermocybe of the basidiomycete genus Cortinarius was investigated. Extracts of all species produced singlet oxygen and are thus photoactive. Pigment analysis was performed and showed similarities of the anthraquinone pigments across the species in dependency to their respective pigmentation types. Detailed content analysis of the pigments in the whole agaricoid fruiting body compared to the three different tissue types (pileus, stipe, and lamellae) revealed that the pigments emodin, dermocybin, and dermorubin, as well as their respective glycosides, are enhanced in the gills. In an independent experiment, the gills were shown to be the most photoactive tissues of the fruiting body. Photobiological experiments with invertebrates (i.e., glassworm Chaoborus crystallinus) proved a phototoxic effect of the methanolic extract of the red blood webcap (Cortinarius sanguineus var. aurantiovaginatus). This work adds further evidence to a common photobiological trait in Cortinarius subgenus Dermocybe and underpins the possibility of a photochemical defense mechanism in fungi.

Evaluation of orellanine-induced toxicity from the mushroom Cortinarius orellanus and the antagonistic effect of Petroselinum crispum.

Mushroom poisoning is a worldwide public health problem that may cause serious toxic consequences on renal functions. The study aimed to evaluate the acute toxicity (24 h) of orellanine (OR) from Cortinarius orellanus in rat kidney and the ameliorative effect of parsley ethanolic extract. Twelve adult male Wistar rats were used to determine intraperitoneal (ip) median lethal dose (LD50) of OR, and 32 rats were divided into 4 groups (n = 8): OR group had 500 mg OR per kg bwt; OR + parsley group had the same dose of OR and after 1 h had 500 mg/kg parsley orally; parsley group had parsley only; and control had the vehicle 0.1% DMSO. Blood and kidney samples were collected at Hour 48. The LD50 dose was 1430 mg/kg for an observation period of 24 h. There were significant reductions (p < 0.01) in the body weight, and relative kidney weight of intoxicated rats compared to parsley treated rats and to controls. Similarly, this group had significantly higher levels of creatinine (p < 0.001), uric acid and urea (p < 0.05). The antioxidant glutathione peroxidase activity was significantly reduced (p < 0.01), while Cystatin C serum levels were significantly higher (p < 0.001) in the intoxicated untreated rats compared to all groups. Histopathological examination indicated necrotic damage in glomeruli and proximal tubules of rats given OR, which was relieved by parsley extract. Overall, the study showed that parsley extract ameliorated OR-induced kidney toxicity. This could be utilized in future research on adjunct therapy for toxicity-induced renal injury.

The photosensitizer emodin is concentrated in the gills of the fungus Cortinarius rubrophyllus.

The colorful agaricoid fruiting bodies of dermocyboid Cortinarii owe their magnificent hue to a mixture of anthraquinone (AQ) pigments. Recently, it was discovered that some of these fungal anthraquinones have an impressive photopharmacological effect. The question, therefore, arises as to whether these pigments are also of ecological or functional significance. According to the optimal defense hypothesis, toxic molecules should be enriched in spore-producing structures, such as the gills of agarics. To test this hypothesis, we studied the distribution of fungal AQs in the fruiting body of Cortinarius rubrophyllus. The fungus belongs to the well-studied Cortinarius subgenus Dermocybe but has not been chemically characterized. Here, we report on the pigment profile of this beautiful fungus and focus on the distribution of anthraquinone pigments in the fruiting body for the first time. Here it is statistically confirmed that the potent photosensitizer emodin is significantly enriched in the gills. Furthermore, we show that the extract is photoactive against cancer cells and bacteria.

Targeted isolation of photoactive pigments from mushrooms yielded a highly potent new photosensitizer: 7,7'-biphyscion.

Pigments of fungi are a fertile ground of inspiration: they spread across various chemical backbones, absorption ranges, and bioactivities. However, basidiomycetes with strikingly colored fruiting bodies have never been explored as agents for photodynamic therapy (PDT), even though known photoactive compound classes (e.g., anthraquinones or alkaloids) are used as chemotaxonomic markers. In this study, we tested the hypothesis that the dyes of skin-heads (dermocyboid Cortinarii) can produce singlet oxygen under irradiation and thus are natural photosensitizers. Three photosensitizers based on anthraquinone structures were isolated and photopharmaceutical tests were conducted. For one of the three, i.e., (-)-7,7'-biphyscion (1), a promising photoyield and photocytotoxicity of EC50 = 0.064 µM against cancer cells (A549) was found under blue light irradiation (λexc = 468 nm, 9.3 J/cm2). The results of molecular biological methods, e.g., a viability assay and a cell cycle analysis, demonstrated the harmlessness of 1 in the dark and highlighted the apoptosis-inducing PDT potential under blue light irradiation. These results demonstrate for the first time that pigments of dermocyboid Cortinarii possess a so far undescribed activity, i.e., photoactivity, with significant potential for the field of PDT. The dimeric anthraquinone (-)-7,7'-biphyscion (1) was identified as a promising natural photosensitizer.

Bioactive Monomer and Polymer Polyketides from Edible Mushroom Cortinarius caerulescens as Glutamate Dehydrogenase Inhibitors and Antioxidants.

Two new polyketides named rufoolivacin E and viocristin B, a new natural product named 1-hydroxy-3,6,8-trimethoxyanthraquinone, and 13 known compounds were isolated from edible mushroom Cortinarius purpurascens in this work. Their structures were assigned on the basis of high-resolution electrospray ionization mass spectrometry, 1D and 2D nuclear magnetic resonance, and electronic circular dichroism data. Notably, the enzyme activity test on glutamate dehydrogenase indicated that 1, 3, 4, 5, 6, 10, 11, and 15 displayed an excellent inhibition effect. Further kinetic studies showed that the most potent compounds, 4 and 10, possess great potential as competitive inhibitors of glutamate dehydrogenase. Molecular docking and computational chemistry were applied to illustrate the binding mechanism in detail. 2,2-Diphenyl-1-picrylhydrazyl and reactive oxygen species assay results showed that compounds 1, 2, 3, and 8 exhibited significant antioxidant activities with IC50 values of 7.0 ± 0.3, 8.6 ± 0.1, 7.5 ± 0.1, and 2.8 ± 0.2 µg mL-1, respectively. Thus, Cortinarius caerulescens represents a novel resource of these polyketides to be utilized in food selection and drug discovery.

Optimized isolation of 7,7'-biphyscion starting from Cortinarius rubrophyllus, a chemically unexplored fungal species rich in photosensitizers.

Mushrooms such as the dermocyboid Cortinarius rubrophyllus are characterized by strikingly colorful fruiting bodies. The molecular dyes responsible for such colors recently experienced a comeback as photoactive compounds with remarkable photophysical and photobiological properties. One of them-7,7'-biphyscion-is a dimeric anthraquinone that showed promising anticancer effects in the low nanomolar range under blue-light irradiation. Compared to acidic anthraquinones, 7,7'-biphyscion was more efficiently taken up by cells and induced apoptosis after photoactivation. However, seasonal collection of mushrooms producing this compound, low extraction yields, and tricky fungal identification hamper further developments to the clinics. To bypass these limitations, we demonstrate here an alternative approach utilizing a precursor of 7,7'-biphyscion, i.e., the pre-anthraquinone flavomannin-6,6'-dimethyl ether, which is abundant in many species of the subgenus Dermocybe. Controlled oxidation of the crude extract significantly increased the yield of 7,7'-biphyscion by 100%, which eased the isolation process. We also present the mycochemical and photobiological characterization of the yet chemically undescribed species, i.e. C. rubrophyllus. In total, eight pigments (1-8) were isolated, including two new glycosylated anthraquinones (1 and 2). Light-dependent generation of singlet oxygen was detected for the first time for emodin-1-O-ß-D-glucopyranoside (3) [photophysical measurement: Φ∆ = 0.11 (CD3OD)]. Furthermore, emodin (7) was characterized as promising compound in the photocytotoxicity assay with EC50-values in the low micromolar range under irradiation against cells of the cancer cell lines AGS, A549, and T24.

Thaxterogaster revisited: A phylogenetic and taxonomic overview of sequestrate Cortinarius from Patagonia.

In the Patagonian region, Cortinarius is the most diverse and abundant genus of ectomycorrhizal fungi with at least 250 species. Sequestrate forms were until recently documented within the genus Thaxterogaster, a genus now known to be polyphyletic, and many were consequently transferred to Cortinarius. Original descriptions were mostly available in German and Spanish and interpretations of morphological structures outdated. Despite recent advances in Cortinarius systematics, the current classification, diversity, and ecology of sequestrate "cortinarioid" fungi in Patagonia remain unclear. The objective of this study was to provide an update on sequestrate Cortinarius of southern South America. We documented each species with morphological descriptions, photographs, basidiospore scanning electron microscopy (SEM) images, and molecular characterization using nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and nuc 28S rDNA (28S) sequence data. Original descriptions of taxa were also translated to English and revised based on fresh collections. We documented 24 species from Patagonia based on molecular data and conducted morphological and phylogenetic analysis for 18 previously described species based on type and reference specimens. In addition, we formally described two new species. Four additional taxa were provisionally determined as new but require further study. New ITS sequence data were produced from eight type specimens. We also provide a new name, Cortinarius gloiodes, nom. nov., for the taxon previously described as Thaxterogaster gliocyclus. In addition to the species treated in detail, we provided additional reference information and discussion on six described species that remained incompletely known or for which no recent collections were found. Of the 24 taxa documented from Patagonia, 15 species were assigned to 12 current sections in the genus Cortinarius. Analysis of spore ultrastructure showed that sequestrate forms of Patagonian Cortinarius lack a true perisporium.

A group of ectomycorrhizal fungi restricts organic matter accumulation in boreal forest.

Boreal forest soils are important global carbon sinks, with significant storage in the organic topsoil. Decomposition of these stocks requires oxidative enzymes, uniquely produced by fungi. Across Swedish boreal forests, we found that local carbon storage in the organic topsoil was 33% lower in the presence of a group of closely related species of ectomycorrhizal fungi - Cortinarius acutus s.l.. This observation challenges the prevailing view that ectomycorrhizal fungi generally act to increase carbon storage in soils but supports the idea that certain ectomycorrhizal fungi can complement free-living decomposers, maintaining organic matter turnover, nutrient cycling and tree productivity under nutrient-poor conditions. The indication that a narrow group of fungi may exert a major influence on carbon cycling questions the prevailing dogma of functional redundancy among microbial decomposers. Cortinarius acutus s.l. responds negatively to stand-replacing disturbance, and associated population declines are likely to increase soil carbon sequestration while impeding long-term nutrient cycling.

Evaluating mercury concentrations in edible plant and fungi species in the Canadian Arctic environment.

Levels of environmental mercury (Hg) within the Canadian Arctic are a current area of concern. Although efforts have been made to reduce Hg released into the environment, levels remain elevated in flora and fauna. This study examined the concentrations of Hg in soil and naturally occurring edible plant and fungi species, identified by local Inuit residents, from eight locations in Iqaluit, Nunavut, and the surrounding area during the summers of 2018 and 2019. Total Hg concentrations were obtained in 24 soil samples, 112 flora samples from 23 plant and five lichen species, and 157 fungal samples from eight species. Median Hg concentrations in plant species ranged from 0.005 µg g-1 Hg dry weight (dw) in Saxifraga cernua to 0.19 µg g-1 Hg dw in Oxytropis maydelliana. Median concentrations in edible fungi species ranged from 0.084 µg g-1 Hg dw in the Cortinarius croceus (non-puffball species) to 1.6 µg g-1 Hg dw in Lycoperdon perlatum (a puffball mushroom). Additionally, median Hg concentration in puffball species (1.4 µg g-1 ) were higher than non-puffball species (0.12 µg g-1 ). Three puffball species were assessed for methylmercury (MeHg), with mean concentrations ranging from 0.013 to 0.085 µg g-1 MeHg dw. Limited research has been conducted on Hg uptake in naturally occurring edible plant and fungi species of the Canadian Arctic. This study contributes important information on Hg accumulation and processes in edible plant and fungi Arctic species, is the first to focus on plants used by the local Indigenous community, and demonstrates a need for further studies to assess Hg in Arctic environments.

Purple haze: Cryptic purple sequestrate Cortinarius in New Zealand.

CORTINARIUS: is a species-rich ectomycorrhizal genus containing taxa that exhibit agaricoid or sequestrate basidiome morphologies. In New Zealand, one of the most recognizable and common Cortinarius species is the purple sequestrate fungus, C. porphyroideus. We used genome skimming of the almost 100-y-old type specimen from C. porphyroideus to obtain the nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS barcode) and partial nuc rDNA 28S (28S) sequences. The phylogenetic position of C. porphyroideus was established, and we found that it represents a rarely collected species. Purple sequestrate Cortinarius comprise multiple cryptic species in several lineages. We describe four new species of Cortinarius with strong morphological similarity to C. porphyroideus: Cortinarius diaphorus, C. minorisporus, C. purpureocapitatus, and C. violaceocystidiatus. Based on molecular evidence, Thaxterogaster viola is recognized as Cortinarius violaceovolvatus var. viola. These species are associated with Nothofagus (southern beech) and have very similar morphology to C. porphyroideus but are all phylogenetically distinct based on molecular data.

Enzymatic Formation of Rufoschweinitzin, a Binaphthalene from the Basidiomycete Cortinarius rufoolivaceus.

Dimeric polyketides are widespread fungal secondary metabolites. They occur in both ascomycetes and basidiomycetes and, therefore, across fungal phyla. Here we report the isolation of a new binaphthalene, named rufoschweinitzin, from the basidiomycete Cortinarius rufoolivaceus. Rufoschweinitzin consists of two symmetrically 4,4'-coupled torachrysone-8-O-methyl ether moieties. Furthermore, we have identified a binaphthalene biosynthetic gene cluster in an unrelated fungus, the ascomycete Xylaria schweinitzii. Heterologous expression of the encoded cytochrome P450 enzyme verified its coupling activity: dimerization of torachrysone-8-O-methyl ether led to the formation of rufoschweinitzin alongside a hitherto unknown regioisomer, now named alloschweinitzin. We have thus demonstrated enzymatic formation of the basidiomycete's metabolite rufoschweinitzin and made the regiochemistry of alloschweinitzin accessible with an ascomycete-derived enzyme.

137Cs and 40K in Cortinarius caperatus mushrooms (1996-2016) in Poland - Bioconcentration and estimated intake: 137Cs in Cortinarius spp. from the Northern Hemisphere from 1974 to 2016.

Cortinarius caperatus grows in the northern regions of Europe, North America and Asia and is widely collected by mushroom foragers across Europe. This study shows that in the last three decades since the Chernobyl nuclear accident, C. caperatus collected across much of Northern Poland exhibited high activity concentrations of radiocaesium (137Cs) - a long-lived radionuclide. The mushroom appears to efficiently bioconcentrate 137Cs from contaminated soil substrata followed by sequestration into its morphological parts such as the cap and stipe which are used as food. The gradual leaching of 137Cs into the lower strata of surface soils in exposed areas are likely to facilitate higher bioavailability to the mycelia of this species which penetrate to relatively greater depths and may account for the continuing high activity levels noticed in Polish samples (e.g. activity within caps in some locations was still at 11,000 Bq kg-1 dw in 2008 relative to a peak of 18,000 in 2002). The associated dietary intake levels of 137Cs have often exceeded the tolerance limits set by the European Union (370 and 600 Bq kg-1 ww for children and adults respectively) during the years 1996-2010. Human dietary exposure to 137Cs is influenced by the method of food preparation and may be mitigated by blanching followed by disposal of the water, rather than direct consumption after stir-frying or stewing. It may be prudent to provide precautionary advice and monitor activity levels, as this mushroom continues to be foraged by casual as well as experienced mushroom hunters.

Nor-guanacastepene pigments from the Chilean mushroom Cortinarius pyromyxa.

For the first time, the pigment composition of basidiocarps from the Chilean mushroom Cortinarius pyromyxa was studied under various aspects like phylogeny, chemistry and antibiotic activity. A molecular biological study supports the monotypic position of C. pyromyxa in subgenus Myxacium, genus Cortinarius. Four undescribed diterpenoids, named pyromyxones A-D, were isolated from fruiting bodies of C. pyromyxa. Their chemical structures were elucidated based on comprehensive one- and two-dimensional NMR spectroscopic analysis, ESI-HRMS measurements, as well as X-ray crystallography. In addition, the absolute configurations of pyromyxones A-D were established with the aid of JH,H, NOESY spectra and quantum chemical CD calculation. The pyromyxones A-D possess the undescribed nor-guanacastane skeleton. Tested pyromyxones A, B, and D exhibit only weak activity against gram-positive Bacillus subtilis and gram-negative Aliivibrio fischeri as well as the phytopathogenic fungi Botrytis cinerea, Septoria tritici and Phytophthora infestans.

Micetismos: Parte 2: Síndromes con sintomatología demorada y latencia muy larga / Mushroom poisonings. Part 2: Delayed-onset syndromes with very long latency time

En este trabajo se analizan los micetismos menos comunes, caracterizados por la aparición demorada de síntomas y por tiempos de latencia muy largos. Estas intoxicaciones son provocadas por especies de hongos ectomicorrícicos poco comunes. Se analizan: a) Toxíndrome nefrotóxico demorado o retrasado. Micetismo orellánico o por orellanina. b) Toxíndrome con rabdomiólisis. Micetismos por Tricholoma equestre y Tricholoma terreum. c) Toxíndrome encefalopático o neurotóxico retrasado. Micetismo por Pleurocybella porrigens. d) Toxíndrome cardiovascular. Micetismo por Trogia venenata. Se discuten el tiempo de incubación, las características sintomatológicas, el curso clínico, las toxinas responsables de cada micetismo y su mecanismo de acción, y el tratamiento que ha resultado efectivo para la recuperación de los pacientes.

Less common mycetisms, characterized by delayed-onset and very long latency times are analyzed. These intoxications are caused by rare ectomycorrhizal fungal species. The following syndromes have been taken into account: (a) Delayed nephrotoxic syndrome. Orellanic mycetism or mycetism due to orellanin. (b) Syndrome with rhabdomyolysis. Mycetisms by Tricholoma equestre, and Tricholoma terreum. (c) Delayed encephalopathic or neurotoxic syndrome. Mycetism by Pleurocybella porrigens. (d) Cardiovascular syndrome. Mycetism by Trogia venenata. The incubation time, symptom characteristics, clinical course, toxins responsible for each mycetism and their mechanism of action, and treatment that has shown to be effective for patient recovery are discussed.

Neste trabalho, analisam-se micetismos menos comuns, caracterizados pelo aparecimento retardado de sintomas e tempos de latência muito longos. Essas intoxicações são causadas por espécies raras de fungos ectomicorrízicos. São analisados os seguintes: (a) síndrome de toxicidade nefrotóxica retardada ou atrasada. Micetismo orelânico ou micetismo por orelanina. (b) Toxíndrome com rabdomiólise. Micetismo por Tricholoma equestre e Tricholoma terreum. (c) Toxicidade tardia encefalopática ou neurotóxica. Micetismo por Pleurocybella porrigens. (d) Síndrome cardiovascular. Miceticismo por Trogia venenata. O tempo de incubação, as características sintomatológicas, o curso clínico, as toxinas responsáveis por cada micetismo e seu mecanismo de ação e o tratamento efetivo para a recuperação dos pacientes são discutidos.

Unveiling new sequestrate Cortinarius species from northern Patagonian Nothofagaceae forests based on molecular and morphological data.

Because of systematic sampling campaigns in the northern Patagonian Nothofagaceae forests of Argentina, several specimens of sequestrate fungi were collected. Some of those collections showed phylogenetic affinities and morphological similarities to members of the formerly recognized sequestrate genus Thaxterogaster, currently a synonym of Cortinarius on the basis of molecular data. Comparisons of macro- and micromorphological features and sequences of nuc rDNA internal transcribed spacer (ITS) regions have revealed that these collections belong to formerly undescribed species. The sequences of the four new taxa presented here, Cortinarius flavopurpureus, C. translucidus, C. nahuelhuapensis, and C. infrequens, were combined into a data set including additional sequences generated from herbarium collections and retrieved from public gene databases and analyzed by maximum likelihood and Bayesian inference methods. The four new species were resolved as distinct clades with strong support; at the same time, they showed unique morphological characteristics (hypogeous to subhypogeous habit, complete gasteromycetation, and spore shape and ornamentation) that separate them from previously described Cortinarius species. In addition, several undescribed and/or not previously sequenced species from these forests were detected through phylogenetic analysis of ectomycorrhizal root tip sequences. A key of characters to identify the sequestrate Cortinarius from Patagonia is provided.

New species of Cortinarius sect. Austroamericani, sect. nov., from South American Nothofagaceae forests.

In this study, we document and describe the new Cortinarius section Austroamericani. Our results reveal high species diversity within this clade, with a total of 12 recognized species. Of these, only C. rufus was previously documented. Seven species are described as new based on basidiomata collections. The four remaining species are only known from environmental sequences. All examined species form ectomycorrhizal associations with species of Nothofagaceae and are currently only known from Argentinean and Chilean Patagonia. The phylogenetic analysis based on the nuc rDNA internal transcriber spacer (ITS1-5.8S-ITS2 = ITS) and partial 28S gene (28S) sequences shows that this section is related to other taxa from the Southern Hemisphere. Species in this group do not belong to subg. Telamonia, where C. rufus was initially placed. Cortinarius rufus and the newly described C. subrufus form a basal clade within sect. Austroamericani that has a weakly supported relationship with the core clade. Because the two species are morphologically similar to species from the core clade and share their distribution and Nothofagaceae associations, we include them here as part of sect. Austroamericani sensu lato (s.l.) until more material is available to refine the delimitation.