New species of Retiboletus (Boletales, Boletaceae) from China based on morphological and molecular data

Species of the genus Retiboletus in China were investigated based on morphology and phylogenetic analysis of DNA sequences from the nuclear ribosomal large subunit (nrLSU) and the translation elongation factor 1-α gene (TEF1-α). Nine species were recovered from China, including two new and seven known species. The new species, namely Retiboletus ater and R. sinogriseus, from southwestern and northeastern China respectively, are documented and illustrated in this paper. Retiboletus ater is morphologically characterized by its black to grayish black pileus, white to grayish hymenophore, black to blackish stipe and white to grayish white context. Retiboletus sinogriseus is morphologically characterized by its brown to grayish-brown pileus, yellow to grayish-yellow hymenophore, pale yellow to brownish stipe and yellow to brownish-yellow context. Descriptions and line drawings of these two novel species and their comparisons with allied taxa are presented.