Mycena clariviolacea is a mushroom in the family Mycenaceae. First reported as a new species in 2007, it is known only from Kanagawa, Japan, where it fruits on dead fallen twigs in forests dominated by oak and chinquapin trees. Distinctive features of this species are found in its medium-sized, dark violet fruit bodies, with caps up to in diameter and slender stems that are about long. Microscopic characteristics include the amyloid spores (staining when treated with Melzer's reagent), the club-shaped cheilocystidia (cystidia on the gill edge) that are covered with one or more, knob-like, apical protuberances, the absence of pleurocystidia (cystidia on the gill face), and the cylindrical, diverticulate caulocystidia (cystidia on the stem). Taxonomy, naming, and classification The mushroom was first collected by Japanese mycologist Haruki Takahashi in 2000, and, along with seven other Mycena species, was reported as a new species in a 2007 publication. The specific epithet is derived from the Latin words clari- (meaning "clear") and violacea ("violaceous"). The Japanese name is Shikon-sakuratake (シコンサクラタケ). According to Takahashi, the amyloid spores, the cheilocystidia covered with one or more, knob-like, apical excrescences, the diverticulate elements in the cortical layer of cap and stem, and the diverticulate caulocystidia suggest that the species is best classified in the section Fragilipedes, as defined by the Dutch Mycena specialist Maas Geesteranus. Description Depending on the age of the mushroom, the cap can range in shape from conic to convex to bell-shaped to somewhat flattened in age; it reaches in diameter. It is sometimes shallowly umbilicate (with a small depression like a navel), radially grooved almost to the center, and somewhat hygrophanous (changing color as it loses or absorbs water). The cap surface is dry, and pruinose (covered with what appears to be a fine white powder), but this soon sloughs off, leaving the surface smooth. Initially, the cap color is dark violet, but it later fades to grayish-violet around the edges. The whitish flesh is up to 0.5 mm thick, and lacks any distinctive taste or odor. The slender stem is long by thick, cylindrical, centrally attached to the stem, and hollow. Its surface is dry, pruinose over the entire length, and grayish-violet to dark violet in color. The base is covered with a white mycelial tomentum (a hairy covering of short, closely matted hairs). The gills are adnate (fused to the stem), and distantly spaced, with about 15–19 gills reaching the