Mario Rajchenberg

Steccherinum and its allied genera represent a morphologically complex group of fungi within the Steccherinaceae . In this study, we investigated, through morphological and multigene phylogenetic analyses, the diversity of odontioid/hydnoid Steccherinum s.l. collected in Brazil. Culture studies were conducted to compare mycelial morphology and growth rates among species, and mating tests were performed to assess sexual compatibility among related taxa. In addition, divergence-time estimates for the Steccherinaceae were generated using a concatenated five-gene dataset to contextualize the evolutionary history of the group. Molecular data revealed eight well-defined neotropical lineages in Steccherinum , including S. larssonii , S. perparvulum , S. subochraceum , and five new species: S. bononiae , S. elegantissimum , S. molle , S. resinaceum , and S. undulatum . The five newly described taxa are morphologically very similar and differ only in subtle diagnostic traits. Two additional new species were identified in Cabalodontia : C. albofulva and C. brunnea . Furthermore, the new combinations C. lincangense and C. tenuissima are proposed based on the phylogenetic data. Phylogenetic analyses also demonstrated that S. perparvulum comprises a species complex with three distinct lineages. Mating tests between two of these lineages showed a lack of sexual compatibility, indicating that they represent separate biological species that cannot be distinguished morphologically. Mycelial culture studies also revealed generally similar morphology with variable growth rates among taxa. Divergence-time estimates indicate a crown age of approximately 86.4 Ma for the Steccherinaceae and a predominantly Cenozoic diversification, with Steccherinum originating in the Eocene. Our findings highlight significant cryptic diversity within Steccherinum in the Neotropics and provide new insights into the taxonomy and phylogeny of the genus.

Fungal communities inhabiting leaves are key players in ecosystem processes but remain largely unexplored in Southern Hemisphere temperate forests. We characterized the foliar mycobiota of Nothofagus pumilio, a dominant deciduous tree in Patagonian forests, using ITS1 metabarcoding across seasons and tree health conditions. We detected 426 fungal taxa, including a 40-Amplicon Sequence Variant (ASV) core mycobiome persisting year-round. Fungal richness and biomass increased significantly in autumn, coinciding with leaf senescence, and community composition shifted markedly between seasons. Spring leaves were enriched in pathogens and basidiomycetous yeasts, while autumn leaves hosted more saprotrophs, ascomycetous yeasts, and lichen-associated fungi. Tree health had limited influence on overall community structure, but symptomatic trees showed higher ASV richness and specific indicator taxa, including the pathogen Trichosporiella multisporum and members of the Taphrinaceae and Saccotheciaceae families. Despite taxonomic turnover, ecological guilds remained relatively stable, suggesting functional redundancy. These findings reveal a seasonal successional trajectory in the foliar mycobiota of N. pumilio, from early-colonizing endophytes in spring to diverse decomposer assemblages in autumn. This study provides the first high-throughput insight into the structure and dynamics of foliar fungal communities in Southern Hemisphere temperate forests, offering a baseline for understanding microbial roles in forest health and resilience.

This study presents a comprehensive phylogenetic analysis of the genus Meripilus and its allied genera Henningsia and Physisporinus within the Meripilaceae family, in the broader context of the residual polyporoid clade. The three genera are morphologically similar and characterized by resupinate to pileate basidiomes that harden and often darken upon drying, a monomitic hyphal structure, simple-septate generative hyphae, and globose to ovoid basidiospores, with variable presence of cystidia. Species in Henningsia and Meripilus, in turn, present gloeopleurous hyphae in the context and large, multipileate basidiomes. Recent studies have indicated that Physisporinus, as currently defined, is not monophyletic, with Meripilus nested within it. Phylogenetic analysis based on four molecular markers confirmed the paraphyletic nature of Physisporinus, with Meripilus and Henningsia both nested within it. Morphological examinations of specimens collected in South America, along with revisions of type specimens, show that this segregation is not natural and causes nomenclatural problems. We propose to transfer all species currently placed in Physisporinus into Meripilus, thereby preventing the division of the genus into morphologically indistinguishable groups. As a result of this reclassification, we propose 35 new combinations in Meripilus and describe three new species from South America.

The identity of Peniophora specimens from Patagonia is examined based on morphological, cultural, and biological features as well as phylogenetic analyses of nuclear ribosomal ITS and 28S sequences. Three new species are described from Patagonia: Peniophora patagonica, P. pitrae, and P. revoluta. In total, five species are known in the area, growing on endemic trees in Southern Argentina. Peniophora cinerea and P. rufomarginata are excluded from the Patagonian records, and the presence of P. incarnata and P. lycii is confirmed by molecular methods. A key to Peniophora species from Patagonia is presented.

A new and threatened polypore species, Bondarzewia loguerciae, is described from the cloud forests of southern Brazil. It is characterized by single-pileate basidiomata that grow on dead branches and along living stems of standing trunks and present a context with dark lines and resinous tubes. When growing in axenic culture, this species also develops chlamydospores. We provide an illustrated morphological description and molecular analysis. Our specimens from Brazil form a monophyletic group among other species of the Southern Hemisphere. The conservation status of B. loguerciae is assessed and published as "Critically Endangered" based on the International Union for Conservation of Nature (IUCN) criteria. Additionally, a key to the species is provided.

High-throughput sequencing approaches have become frequent in the study of endophyte communities allowing the cumulative description of fungal diversity in the last decade. However, they brought new challenges to researchers in terms of programming and developing of informatics tools. Currently, there is no consensus concerning the appropriate bioinformatics to process such sequence data. The aim of this study was to compare the performance of three pipelines of two cost-free toolkits designed to be friendly to non-programmer users, and specifically developed for fungal data: AMPtk and PIPITS. The sapwood-inhabiting fungal assemblages of two Nothofagus species from the Patagonian Forests were assessed through metabarcoding of the internal transcribed spacer (ITS) and compared with an extant sequence dataset obtained from culture prospection in the same study sites and trees. The AMPtk toolkit has performed better concerning community description in terms of precision of taxa clustering, mainly due to the DADA2 algorithm; PIPITS evidenced a higher sensitivity in detecting taxa known to be present, hence it is potentially useful for future specific taxa detection surveys. Because of a current lack of information of the reference databases, both bioinformatic toolkits performed poorly as to taxonomy assignment. It is imperative to continue studying these ecosystems to, concomitantly, improve databases and the explanatory potential of the new technologies.

Fungal polysaccharides possess a broad biological activity, including cytotoxic and antioxidant activities. This work aimed to evaluate the cytotoxic and antioxidant activity of the acidic polysaccharides of Phylloporia boldo strain (named PBAP40). Cytotoxic activity of polysaccharide was evaluated determining the viability of three tumor cell lines by MTT assay. The effect of acidic polysaccharide on the cell cycle of HL-60 cell line was evaluated by flow cytometry, and the antioxidant activity was determined by DPPH and ABTS assays. PBAP40 showed cytotoxic effects in tumor cell lines. Results suggest that P. boldo acidic polysaccharides arrested tumor cells in the cell cycle Sub G1 phase. The acidic polysaccharides of PBAP40 strain were not cytotoxic for the non-tumor cell line. PBAP40 also showed excellent antioxidant activity. The FT-IR analysis of the acidic polysaccharides indicated the presence of glucans bearing α- and β- type glycosidic bonds. Graphical Abstract