Abstract
Lepiota thailandica, widely distributed across northern Thailand, is described as a new species and is recognizable by its tiny basidiomata, convex or umbonate pileus, covered with reddish brown squamules on a white fibrillose background, free lamellae, white cylindrical stipe sometimes with brown squamules at the basal zone, hyaline and ellipsoid to oblong ovoid basidiospores, clavate to utriform cheilocystidia, trichodermal structure of squamules on the pileus and stipe, and clamp-connections in all tissues. Morphological characters and nrITS sequence data indicate that the species belongs in the section Ovisporae, subsection Felininae, which contains species with a trichodermal pileus covering made up of long and short elements.