Morphology and multigene phylogeny reveal two new species of Micropsalliota (Agaricaceae, Basidiomycota) from Dhofar region, southern Oman.

Micropsalliota is a genus of small to relatively medium-sized saprotrophic mushrooms, with fibrillose-squamulose pileus surface, ellipsoid to amygdaliform or cymbiform basidiospores, usually with capitate cheilocystidia, and encrusted pileus hyphae. In this study, two new species, namely Micropsalliota latiumbonata and M. striata are described from Oman, based on morphology and multigene (ITS-28S-rpb2-tef1-α) phylogenetic analysis. Micropsalliota latiumbonata is characterized by a broadly umbonate pileus disc with fibrillose-squamulose surface, fibrils dark-brown and more or less recurved, cheilocystidia capitate with olivaceous capitulum, broadly fusiform to amygdaliform basidiospores measuring 6.0-7.0 × 4.0-4.5 µm, and occurring gregariously around termite mounds. Micropsalliota striata is another small-sized species with an acute papillate pileus disc with appressed fibrils, striate-appendiculate pileus margins, utriform cheilocystidia without a capitate apex, clavate to subglobose pileocystidia, and comparatively larger basidiospores (6.5-7.5 × 3.7-4.1 µm). Both the new species belong to Clade megaspora. A detailed description, photographs of basidiomata, illustrations of anatomical characteristics, a multigene phylogenetic tree, and morphological comparison with similar species are provided. With the description of these two species, the number of known species in Micropsalliota rises to 108.