Morphological characterisation and phylogenetic placement of the very rare species Psathyrella sulcatotuberculosa

A recent find of the very rare species Psathyrella sulcatotuberculosa (Psathyrellaceae) from Italy provided the authors with new data useful for improving the knowledge of an almost mysterious entity. Of this collection, a detailed morphological description, a statistical analysis of the spore size along with several photographs of the basidiomata in field and microscopical structures are provided and compared with the features of the type collection. Morphologically and/or molecularly allied species are discussed. Phylogenetic analysis of Psathyrellaceae based on sequence data from the nuclear ribosomal DNA internal transcribed region and partial large subunit placed P. sulcatotuberculosa in the P. candolleana clade with strong statistical support, together with P. candolleana, P. badiophylla, P. leucotephra and P. typhae. The result is also supported by morphology, where the species in the clade all lack pleurocystidia but have clavate, utriform and lageniform cheilocystidia with a rounded apex.