Marasmius neooreades sp. nov. from Japan is described. This species produces fleshy, medium-sized basidiomata that are macromorphologically similar to M. oreades, with a pileus ranging from wheat-colored to dark brown and a tough stipe covered with brownish tomentose squamules. The gill edges bear cheilocystidia that are clavate to diverticulate. The pileipellis is hymeniform and composed of Globulares-type elements containing brown pigments. The species typically occurs gregariously in grasslands and occasionally forms fairy rings. Phylogenetic analyses based on ITS and LSU sequences indicated that M. neooreades forms a well-supported, independent clade distinct from previously described species of Marasmius. In addition, a combination of morphological characters clearly differentiates this species from all described taxa. An illustrated description and the phylogenetic placement of the new species are provided.
Oguchi et al. (Wed,) studied this question.