Geastrum argentum (Geastraceae, Basidiomycota): a new earthstar fungi species from the Atlantic Rainforest

Geastrum argentum sp. nov: is a new species found in the Atlantic Rainforest biome of the northeast region of Brazil. Phylogenetic analyses of ITS/LSU and morphological data indicate that this species is phylogenetically positioned in sect. Myceliostroma subsect. Epigaea, forming a distinct species. Sequences of the internal transcribed spacers (ITS) and large subunit (nrLSU) of the nuclear ribosomal DNA were generated and the phylogenetic analyses were performed with maximum likelihood (ML) and Bayesian inference methods. The new species shows morphological and phylogenetic proximity to Geastrum rubellum, G. trachelium, G. suae and G. yanshanense. In ML and Bayesian inference we recovered the same topologies in both datasets, indicating the correct positioning of the species. The discovery of this new species highlights the diversity of taxa in this underexplored region, emphasising the need for continuous research in areas threatened by deforestation and urbanisation. The description, discussion, and photographs of this new taxon are provided.