Abstract

Psathyloma is an agaricoid genus described recently to accommodate two species of brown-spored agarics from Australasia superficially similar to Psathyrella and Hebeloma. Phylogenetic analyses published along with the description of the genus determined that an unidentified species of Psathyloma was also present in Patagonia based on ITS sequences from ectomycorrhizal root tips of Nothofagaceae trees. Based on morphological and phylogenetic analyses of fresh mushroom collections from Patagonia, we determine that the unknown South American Psathyloma corresponds to Pholiota psathyrelloides, a species described by Rolf Singer in 1969 from Nothofagaceae forests in Argentina. Here we transfer this species to the genus Psathyloma and provide detailed morphological data and illustrations of fresh collections. Psathyloma is confirmed as an ectomycorrhizal genus with a disjunct southern Gondwanan distribution that is similar to what has been found for other Austral ectomycorrhizal fungal genera such as Austropaxillus and Descolea.