Xanthagaricus pakistanicus sp nov (Agaricaceae): first report of the genus from Pakistan

Xanthagaricus pakistanicus is described as a new species from lowland northern Pakistan, based on morphological and molecular data. It is characterized by a yellowish pileus, covered with dark brown squamules, a stipe with yellowish fibrils, globose basidiospores, and pileal squamules made up of pseudoparenchymatous epithelium with encrusted walls. Molecular phylogenetic trees were inferred based on nucleotide sequences of the internal transcribed spacer (ITS1-5.8S-ITS2) region and 28S nuclear ribosomal DNA. In phylogenetic analyses the genus Hymenagaricus sensu lato (s. l.) was inferred as a nonmonophyletic group and recovered in two monophyletic clades, consisting of species of the genera Xanthagaricus and Hymenagaricus sensu stricto (s. str.). On account of the pileal squamule structure (pseudoparenchymatous epithelium) and yellowish basidiospores, and the phylogenetic position in the Xanthagaricus clade the new species X. pakistanicus belongs to the genus Xanthagaricus. Morphoanatomical comparison with the known species of Xanthagaricus is provided. We also made six new combinations in Xanthagaricus: X. calicutensis, X. epipastus, X. ochraceoluteus, X. rufomarginatus, X. subaeruginosus, and X. taiwanensis. With this study the number of known species in the genus Xanthagaricus increases to 19.