Mycena fonticola is a species of fungus in the family Mycenaceae. First reported in 2007, it is known only from central Honshu, in Japan, where it grows on dead leaves and twigs in low-elevation forests dominated by oak trees. The fruit body of the fungus has a smooth, violet-brown cap up to in diameter, and a slender stem up to long. Distinguishing microscopic characteristics of the mushroom include the relatively large, distinctly amyloid spores (turning blue to black when stained with Melzer's reagent), the smooth, spindle-shaped cheilocystidia (cystidia on the gill edge), the absence of pleurocystidia (cystidia on the gill face), the diverticulate hyphae of the cap cuticle, and the absence of clamp connections. Taxonomy, naming, and classification The fungus was first collected by Japanese mycologist Haruki Takahashi in 1999, and described as a new species along with seven other Japanese Mycenas in a 2007 publication. The mushroom's Japanese name is Izumino-ashinagatake (イズミノアシナガタケ). The specific epithet fonticola is derived from Latin, and means "dweller in fountain". According to Takahashi, various macro- and microscopic features suggest that this species is best classified in the section Fragilipedes (Fr.) Quél., as defined by the Dutch Mycena specialist Maas Geesteranus. Description The cap is in diameter, and ranges in shape from conical to convex to bell-shaped. The surface has radially arranged shallow grooves extending almost to the center of the cap. The cap surface is somewhat hygrophanous (changing color as it loses or absorbs water), dry, and smooth. It is colored violet-brown when young, then becomes somewhat paler from the margin. The white flesh is up to 1 mm thick, and lacks any distinctive odor or taste. The stem is long and slender compared to the size of the cap, typically tall by thick, cylindrical, slightly enlarged at the base, and hollow. It is grayish-brown to violet-brown at the top, gradually becoming violet-brown on the lower portion. The stem surface is initially pruinose (appearing to be covered with a fine whitish powder), but becomes smooth in age. The stem base bears large, bristle-like coarse white hairs. The gills are adnexed (narrowly attached to the stem), with between 23 and 27 reaching the stem. The gills are up to broad, thin, and have a whitish or with a grayish hue; the gills edges are the same color as the gill faces. Microscopic characteristics The spores are ellipsoid, smooth, colorless, distinctly amyloid (absorbing iodine stain from