Molecular phylogeny of the Tiliae group (Inocybe sect. Marginatae) and delimitation of the group with new discoveries

The Inocybe tiliae group (sect. Marginatae ) was previously known mainly from Europe. In this study, a multigene phylogeny of the group was reconstructed based on ITS, LSU, and rpb2 sequences, incorporating extensive collections from subtropical and temperate China for the first time. Four new species, I. qiongzhuensis sp. nov ., I. ravida sp. nov ., I. xihuensis sp. nov ., and I. zijinshanensis sp. nov ., are described, and three taxa, I. tiliae , I. dunensis , and the I. pallida / I. nobilis complex, are reported for the first time from China. Phylogenetic analyses recovered a fully supported major clade comprising the former core lineage, I. robertii , the Dunensis clade, and the four new Chinese species. The Pseudohiulca clade is sister to this major clade, whereas the Velata clade is sister to all the aforementioned lineages. Based on these results, the circumscription of the Tiliae group is expanded to include the major clade, the Pseudohiulca clade, and the Velata clade, comprising 12 species plus the I. pallida / I. nobilis complex and the I. pseudohiulca complex. The broad Tiliae group is defined by a combination of morphological traits: robust basidiomata, a yellowish-ochraceous to dark brown pileus, a stipe often with pinkish tones, a bulbous or marginate stipe base, a stipe that is either entirely pruinose or at least pruinose in the upper half, and often a spermatic odor.