Inocybe is the largest genus in the family Inocybaceae, with approximately 1000 species worldwide. Basic data on the species diversity, geographic distribution, and the infrageneric framework of Inocybe are still incomplete because of the intricate nature of this genus, which includes numerous unrecognized taxa that exist around the world. A multigene phylogeny of the I. umbratica-paludinella group, initially designated as the "I. angustifolia subgroup", was conducted using the ITS-28S-rpb2 nucleotide datasets. The seven species, I. alabamensis, I. angustifolia, I. argenteolutea, I. olivaceonigra, I. paludinella, I. subangustifolia, and I. umbratica, were confirmed as members of this species group. At the genus level, the I. umbratica-paludinella group is a sister to the lineage of the unifying I. castanea and an undescribed species. Inocybe sect. Umbraticae sect. nov. was proposed to accommodate species in the I. umbratica-paludinella group and the I. castanea lineage. This section now comprises eight documented species and nine new species from China, as described in this paper. Additionally, new geographical distributions of I. angustifolia and I. castanea in China are reported. The nine new species and I. angustifolia, I. castanea, I. olivaceonigra, and I. umbratica are described in detail and illustrated herein with color plates based on Chinese materials. A global key to 17 species in the section Umbraticae is provided. The results of the current study provide a more detailed basis for the accurate identification of species in the I. umbratica-paludinella group and a better understanding of their phylogenetic placement.
Keywords: Asia; Inocybaceae; new taxa; rpb2; systematics.