Three nodulose-spored Inocybe (Agaricales, Basidiomycota) species discovered from Motuo, Southwest China

The species diversity of the ectomycorrhizal family Inocybaceae is poorly understood in tropical regions. The present work concerns a survey of macrofungi from Motuo in Xizang, which is located at the northern edge of China's tropical zone. Three new species were identified using morphological features and DNA sequences (ITS, LSU and RPB2). Inocybe flavitomentosa sp. nov. belongs to section Umbraticae. It has a yellow, densely hairy cap and angular spores with faint knobs. This is the first species in its group to be found in the Chinese tropics. Inocybe motuoensis sp. nov. forms a basal branch in the I. xanthomelas group. It is the only purely tropical species in this group. It has a yellowish-brown cap, no caulocystidia and spores bearing 7-11 rounded nodules. Inocybe subchondrospora sp. nov. belongs to the I. fibrosoides group. Resembling the northern species I. chondrospora, it has smaller spores (10.1-12.9 × 6.0-7.2 µm) and grows in subalpine areas at an elevation of 2,400-2,500 m. These discoveries expand the known range of Inocybe in tropical Asia and support the idea that the I. xanthomelas group likely originated in tropical regions.