Unravelling the ‘Helan Mountain Zimo’ complex: Collybia zimo sp. nov. and Collybia violea (Clitocybaceae, Agaricales), a new species and a new distribution record from Ningxia, China

The fungus locally known as ‘Zimo’ (purple mushroom) is a popular wild edible fungus in the Helan Mountain region, yet its taxonomic identity has long remained ambiguous. In this study, we clarified the taxonomy of the ‘Zimo’ specimens collected from the Helan Mountains using multi-locus (ITS + nrLSU + rpb2 + tef 1-α) phylogenetic analyses and morphological observations. The results show that ‘Zimo’ is not a single species but a species complex comprising at least two Collybia species. One is C. violea , for which we provide a supplementary description based on specimens from new localities. The other is a new species, described here as C. zimo sp. nov., which is characterized by a purplish white to deep purplish grey pileus covered with purplish grey fibrils, verrucose basidiospores (Qav = 1.39), and wide pileipellis hyphae (7–17 μm). Phylogenetically, C. zimo is placed within Collybia subgen. Leucocalocybe and forms a distinct lineage sister to Clitocybe violaceifolia with strong support. Our results reveal the fungal diversity hidden behind the vernacular name ‘Zimo’. Additionally, based on phylogenetic evidence, we recombined Clitocybe cedrelae as Collybia cedrelae comb. nov.