Phylogenetic analysis, Basidiomycota, diversity, macrofungi, Amazon region.

" Hymenochaetaceae (Hymenochaetales, Agaricomycetes) is a family of macrofungi comprising a diversity of approximately 830 species. Species of this family function as saprotrophs, pathogens, and ectomycorrhizal organisms, playing a fundamental role in natural ecosystems. For several years, the identification of taxa within this family was based primarily on morphological characteristics. However, given that many species exhibit limited heterogeneity in phenotypic traits, the use of molecular phylogeny data has become an important method for taxa delimitation. This study aimed to conduct a taxonomic investigation through morphological and molecular analyses of Hymenochaetaceae species from areas of the eastern Brazilian Amazon. Initially, a survey of Hymenochaetaceae species in the Brazilian Amazon was conducted based on scientific literature and database records. A total of 80 taxa were recorded, of which 46 were considered valid, while 34 were deemed doubtful due to the absence of phylogenetic and ecological data; these doubtful records were excluded from the region (Chapter I). Morphological and phylogenetic analyses were performed on 97 samples collected in the states of Pará and Amapá, leading to the description of four new species. A new species of Fulvifomes, along with F. kawakamii, was recorded in floodplain areas of the lower Tocantins region (Pará). Phylogenetic analyses using ITS and LSU markers, combined with morphological and ecological data, confirmed the new species. Additionally, illustrations and a key to the genus are presented (Chapter II). Three new species of the genus Fuscoporia were described based on an integrative study combining morphology and multilocus analyses of the ITS, LSU, RPB2, and TEF1-α genes. The new species exhibit distinctive morphological characteristics and strong statistical support, differentiating them from other Fuscoporia species. Morphological descriptions, illustrations, and comparisons with species from the Brazilian Amazon are provided (Chapter III). This study expanded the distribution of Hymenochaetaceae species in the eastern Brazilian Amazon. The integrative approach combining phenotypic and molecular traits provided evidence for the delimitation of new species, highlighting the potential of Amazonian biodiversity. Furthermore, the data may contribute to conservation strategies and future studies aimed at understanding the phylogenetic relationships within Hymenochaetaceae.