Mycena nidificata is a species of fungus in the Mycenaceae family of the Agaricales. First collected in 2000 and reported as a new species in 2007, it is known only from Kanagawa, Japan, where it grows on the floor of oak forests. The dark brown irregularly wrinkled cap measures up to 25 mm (1.0 in) in diameter. The cap is supported by a thin stem up to 50 mm (2.0 in) long, which is covered at the base by a whitish hairlike growth, and attached to white, cord-like rhizomorphs—aggregations of mycelium that resemble plant roots. The underside of the cap features thin, distantly spaced grayish gills that have distinct veins running between them. At a microscopic level, distinguishing characteristics include the inamyloid spores (turning dark blue to black when stained with Melzer's reagent),