Morphology and molecular phylogeny of four new species of Entoloma (Entolomataceae, Agaricales) from Europe and Western Eurasia

Entoloma is one of the largest genera of Agaricales in terms of species diversity and is widespread throughout the world. In the present study, four new species, namely Entoloma brunneofibrillosum, E. humidiphilum, E. ochraceodiscum, and E. colchicum, are introduced as new to science. These species are described based on specimens collected in Cyprus, Georgia, Hungary, Italy, Russia, Spain, and Türkiye, including morphological characteristics and phylogenetic analyses of the nuclear ribosomal DNA internal transcribed spacer (ITS) sequences. Entoloma brunneofibrillosum is recognized by its brown to dark brown pileus with conspicuous dark, radial fibrils, a pale brown stipe with glistening fibrils, and usually fusiform to broadly clavate cheilocystidia. It belongs to the /Undulatosporum clade. Entoloma humidiphilum (subg. Alboleptonia) is close to E. niveum from New Zealand but differs by a completely pruinose or minutely squamulose pileus surface, narrowly cylindrical to cylindrical pileipellis elements with a deep median constriction, and by occurring in riparian habitats. Entoloma ochraceodiscum is characterized by funnel-shaped basidiomata with a deeply depressed yellowish-brown pileus and belongs to the section Griseorubida. Entoloma colchicum (subg. Nolanea) is similar to E. ortonii but differs by its distinctive radially fibrillose or velutinous pileus and the absence of odour. The new species are presented with photographs, line drawings, and comparisons with similar taxa.