Claim: Gymnopilus testaceus has a cap that is convex and has gills on hymenium (a surface consisting mainly of spore-bearing structures).
Evidence: cap is convex gills on hymenium A basidium (pl., basidia) is a microscopic sporangium (or spore-producing structure) found on the hymenophore of fruiting bodies of basidiomycete fungi which are also called tertiary mycelium, developed from secondary mycelium. The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores.