Description of two new Pluteus species of sect. Pluteus (Agaricales, Pluteaceae) from the Russian Far East based on morphological and molecular data

Two new Pluteus species, P. nigritus and P. fumidus, were described based on specimens collected in the Far East, the easternmost part of Russia. Pluteus nigritus is characterized by rather large basidiomata with dark-coloured blackish brown pileus and greyish brown bulbose stipe, pigmented lamellae edges, metuloid pleurocystidia, presence of clamps in pileipellis, and growing on conifer wood. Another species, P. fumidus, also growing on conifers, has medium-sized basidiomata with greyish brown pileus and silvery-white stipe with grey base, concolorous lamellae edges, metuloid pleurocystidia, and abundant clamp-connections in all tissues. The phylogenetic placements of the two newly described species within Pluteus were confirmed using DNA data (nuclear ribosomal internal transcribed spacer (ITS) and translation-elongation factor 1-alpha (TEF1)). Detailed morphological descriptions, field photographs, and comparisons of two new species with other morphologically and phylogenetically closely related species are provided. Morphological characters and phylogenetic trees inferred from ITS and TEF1 of nc DNA sequences showed that both of our new species belong to the section Pluteus.