Pseudohydnum, commonly known as cat's tongue mushrooms, is a monophyletic assemblage within Auriculariales, which encompasses species with gelatinous basidiomata, spathulate, flabellate, or shell-shaped pileus, hydnoid hymenophore, globose to ellipsoidal basidiospores, and longitudinally cruciate-septate basidia. According to the available literature, 16 species have been described in Pseudohydnum, mostly represented in temperate-boreal forests of the Northern Hemisphere. However, the limited morphological, molecular, and ecological information, especially from the Southern Hemisphere ecosystems, does not presently allow a reliable assessment of its taxonomic boundaries nor provide a complete picture of the species diversity in the genus. In an ongoing effort to examine specimens collected in dense and mixed ombrophilous forest fragments (Atlantic Rainforest domain) from Southeastern and Southern Brazil, additional taxa assigned to Pseudohydnum were identified. Four new species are recognized based mostly on characters of the pileus surface, stipe, hymenium, and basidiospores. Molecular phylogenetic analyses based on nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS barcode), partial nuc rDNA 28S, and partial RNA polymerase II largest subunit (RPB1) sequences supported the description of these new taxa. Here, we propose Pseudohydnum brasiliense, P. brunneovelutinum, P. cupulisnymphae, and P. viridimontanum as new species. Morphological descriptions, line drawings, habitat photos, and comparisons with closely related taxa are provided. A dichotomous key for identification of currently known Southern Hemisphere Pseudohydnum species is presented.

During nocturnal field expeditions in the Brazilian Atlantic Rainforest, an unexpected bioluminescent fungus with reduced form was found. Based on morphological data, the taxon was first identified as belonging to the cyphelloid genus Maireina, but in our phylogenetic analyses, Maireina was recovered and confirmed as a paraphyletic group related to genera Merismodes and Cyphellopsis. Maireina filipendula, Ma. monacha, and Ma. subsphaerospora are herein transferred to Merismodes. Based upon morphological and molecular characters, the bioluminescent cyphelloid taxon is described as the new genus Eoscyphella, characterized by a vasiform to urceolate basidiomata, subglobose to broadly ellipsoid basidiospores, being pigmented, weakly to densely encrusted external hyphae, regularly bi-spored basidia, unclamped hyphae, and an absence of both conspicuous long external hairs and hymenial cystidia. Phylogenetic analyses based on ITS rDNA and LSU rDNA support the proposal of the new genus and confirm its position in Cyphellopsidaceae. Eoscyphella luciurceolata represents a new lineage of bioluminescent basidiomycetes with reduced forms.

This study investigates morphological and genetic diversity in Rhodocybe mellea, after a new record of this species in the Brazilian Atlantic Forest. Phylogenetic analysis of molecular data (nrITS and nrLSU) and pairwise genetic distances, provide support for the recognition of cryptic lineages within R. mellea co-occurring in the Neotropics. We propose Rhodocybe mellea var. depressa as morphologically characterized by its depressed pileus, conspicuous sclerobasidia, small flexuous-cylindrical pseudocystidia, and a smooth cutis pileipellis. In addition, we also determine the position of nrITS sequences of some sclerotium-forming fungi collected in the same area, and confirm the genus Rhodocybe as a producer of this survival structure. Our findings provide unique information on Rhodocybe in South America, and highlight the relevance of approaches that address fine-scale diversity for fungal taxonomy.

Two new species in Lactifluus subg. Pseudogymnocarpi, Lf. umbilicatus and Lf. venosellus were collected from Amazonian and Atlantic forests of Brazil, respectively. Detailed macro- and micromorphological descriptions, including scanning electron microscopy images of the basidiospores, are provided. The putative phylogenetic placement of these taxa was investigated based on ITS sequence analyses. Comparisons with related taxa are discussed.