Mycena fonticola is a species of fungus in the Mycenaceae family. 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 2.5 cm (1.0 in) in diameter, and a slender stem up to 10 cm (3.9 in) 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.