A New Tropical Species of Psathyrella (Psathyrellaceae, Agaricales) From the Cúc Phương National Park, Vietnam

Abstract Basidiocarps of a hitherto undescribed Psathyrella species were collected during a sampling excursion in North Vietnam. They grew on deciduous deadwood in the Southeastern part of the Cúc Phương National Park (Vietnamese: Vườn quốc gia Cúc Phương), Ninh Bình Province. Herein, we describe Psathyrella euryspora sp. nov. characterized by broadly ellipsoid to broadly ovoid basidiospores (5.5–7.0 × 4–5(–6)) µm without visible germ pore, utriform to ventricose-clavate cheilocystidia, heteromorphic caulocystidia and the absence of pleurocystidia and pileocystidia. Based on an isolated pure culture, the genome was sequenced and a full ribosomal RNA gene cistron including 18S, internal transcribed spacer 1 (ITS), 5.8S, ITS2 and 28S rRNA annotated. Phylogenetic analysis of P. euryspora revealed its close affiliation to the Psathyrella sect. Candolleanae species clade.