Mycena lanuginosa is a species of mushroom in the Mycenaceae family. First collected in 2000 and reported as a new species in 2007, it is known only from lowland oak-dominated forests in central Honshu in Japan. The small mushroom is characterized by its grooved, grayish-brown to violet-brown cap up to 11 mm (0.43 in) in diameter, and the slender grayish-brown to reddish-brown stem covered with minute, fine, soft hairs. The mushroom produces amyloid spores (spores that stain when treated with Melzer's reagent). Microscopic distinguishing features include the smooth, spindle-shaped cheilocystidia and pleurocystidia (cystidia on the gill edge and face, respectively) and the diverticulate elements in the outer layer of the cap and the stem.