The family Hymenochaetaceae includes a diversity of 893 species described around the world. Its representatives are known by their usually rusty colored basidiomes with a poroid hymenial surface, hydnoid or smooth, woody consistency, and wide morphological variation regarding the arrangement on the substrate. They behave as saprophytic, parasitic, ectomycorrhizal and play a fundamental role in the decomposition of wood in forest ecosystems. In the Brazilian Amazonia region, approximately 40 species of Hymenochaetaceae are currently recorded. The main goal of this study was to increase the knowledge on Hymenochaetaceae from the Brazilian Amazonia. Collections were carried out between October 2021 and April 2022 in the state of Pará, municipalities of Tomé-Açu and Bujaru, to expanding the knowledge of this fungal family to the Brazilian Amazonia. A total of 15 specimens were identified, distributed in seven genera and 12 species. Four species are new records for the state of Pará (Fomitiporia apiahyna, Phellinus neocallimorphus, Phellinus sancti-georgii, and Sclerotus extensus) and two of them are new records for the Brazilian Amazonia (P. neocallimorphus and P. sancti-georgii). Our findings contribute to taxonomic knowledge of this family in the Brazilian Amazonia and reduce the information gaps about the diversity of species.

Macrofungi are key decomposers of organic matter and play an active role in biogeochemical cycles, thereby contributing to carbon sequestration in forest ecosystems. Floodplain forests (várzeas) are characterized by the dynamics of rising and receding waters, which are rich in suspended material and influence species variation and adaptation. The knowledge about the distribution of macrofungi in várzea environments in the Brazilian Amazon is limited. This study aims to evaluate the diversity and composition of macrofungi on three várzea forest islands, while also examining differences in species richness and abundance between seasonal periods. A total of 88 macrofungal species that belong to the phylum Basidiomycota were identified. The findings revealed significant variations in species composition, yet no notable differences in species richness or abundance were observed between the seasonal periods. The environmental conditions and resources available to macrofungi appear to be consistent among the islands, which leads to a balanced diversity. However, additional research is essential to uncover the true distribution patterns of macrofungi in the várzeas of the Brazilian Amazon, an area under significant threat to its biodiversity.

The Brazilian Amazon occupies an area of ​​around 50% of the Brazilian territory and covers nine states. This region is home to a high diversity of plants and fungi. However, the knowledge of these groups is still limited, which could affect the assessment of their geographic distribution and diversity of species and, consequently, conservation strategies aimed at them. Hymenochaetaceae is a family of fungi in the phylum Basidiomycota and has 893 known species worldwide. The goal of this study was to provide an updated review of the literature and collection databases on the diversity of Hymenochaetaceae species occurring in the Brazilian Amazon. A total of 45 species were confirmed to occur in the region with valid records, while 34 species were considered doubtful in view of the type locality and/or lack of ecological and phylogenetic data, and were excluded from the occurrence list until they undergo a more in-depth review. The most representative genera were Fuscoporia, Coltricia, Hymenochaete and Fomitiporia. The states of Pará and Rondônia had the highest number of species. The 45 valid species of Hymenochaetaceae registered in this study provide a baseline for conservation strategies and policies, and highlight the importance of covering the extensive sampling gaps in the region and to carry out new taxonomic studies to better understand the diversity of fungi in the Amazon.

Fulvifomes is a monophyletic genus of Hymenochaetaceae (Basidiomycota), with a cosmopolitan distribution and ecological importance. Specimens of Fulvifomes were collected from floodplain forest islands in the Brazilian Amazon. Morphological and molecular phylogenetic analyses revealed a new species, Fulvifomes paraensis sp. nov., mainly characterized by its pileate basidioma, broadly attached to dimidiate, hyphal system monomitic in context to subdimitic in trama, and basidiospores broadly ellipsoid to subglobose. This species was found on dead trunks of Mora paraensis, a tree species that is endemic to floodplain areas of the eastern Amazon. Additionally, Fulvifomes kawakamii is reported for the first time in floodplain forests. Notes and illustrations for these two species, and an identification key for the species of Fulvifomes with molecular data from Brazil are provided.