Growing solitary or in clusters on bark of coniferous wood or on coniferous litter (e. g. Thuja, Picea, Pinus, Juniperus); also found on deciduous wood (Elborne and Læssøe 1982), Aronsen A 39/09 on moss covered base of old Salix caprea. Known distribution: Canada, Denmark, France, Norway, Poland, Finland (T. von Bonsdorff, pers. comm.), Switzerland, United States. Mycena clavata seems
to be rare in Europe, and there are only a few collections
from Norway. Autumn. Records in The Norwegian Mycological Database.
Pileus 2–12.5 mm across, at first hemispherical, expanding to parabolical or campanulate when young, then convex, flattening with age, and often somewhat depressed at the centre, translucently striate, pale ochraceous brown, pale grey brown (milky coffee), yellow brown or greyish olivaceous brown, fairly dark when moist and young, pallescent with age, dark sepia brown at the centre, paler at margin, surface minutely pruinose-pubescent, later glabrescent. Flesh very thin, pale beige; smell absent, taste mild. Lamellae 8–20 reaching the stipe, strongly arcuate, long decurrent, slightly paler than cap, pale brown, greyish sepia to beige brown with concave edge, paler than the sides. Stipe 8–80 × 0.2–1 mm, hollow, firm, equal, straight to curved, terete, pruinose all over, glabrescent, paler than the pileus, beige brown, pale yellowish brown, watery yellowish, watery brownish or greyish, the base covered with coarse, whitish fibrils.
Basidia 21–39 × 5–9 µm, slender-clavate or clavate, 2-spored, clampless, with sterigmata 6–7 µm long or 4-spored, clamped. Spores 7–11 × 5.5–8.5(–9.5) µm, qav ~ 1.25 (2-spored basidia), or 6.5–10.5 × 5–7.5 µm, qav ~1.28 (4-spored basidia), broadly ellipsoid, broadly amygdaliform to subglobose, with rounded to slightly conical apex, smooth, non-amyloid. Cheilocystidia 20–88 × 4–16 µm, forming a sterile band, sub-cylindrical, fusiform to lageniform, clamped or clampless, apically passing into a slender, straight to curved or somewhat flexuous, simple, forked or somewhat branched neck 2–5 µm wide, often capped with a large drop of gelatinous matter. More rarely, and mostly situated near the margin of the pileus, another type of cheilocystidia appears, that is shorter, 17–35 × 6–15 µm, narrowly clavate to clavate and with several simple to branched, cylindrical excrescences. Pleurocystidia apparently absent, but cystidia may be present very near the pileus margin. Lamellar trama not staining with Melzer’s reagent. Hyphae of the pileipellis 2.5–6.5 µm wide, clamped or clampless, covered with simple to much branched excrescences up to 22.5 × 1–2 µm, which may develop into very dense masses, sometimes becoming somewhat gelatinized, with some of the diverticulae elongated into projecting, pileocystidia-like hairs up to 32 µm long. Lower layers (hypoderm and context) composed of wider hyphae, 3–10 µm wide, distinctly incrusted with brownish pigment. Hyphae of the cortical layer of the stipe 1.5–3.5 µm wide, clamped or clampless, smooth for the greater part, but covered with side-branches and caulocystidia 35–78 × 3–11 µm; the caulocystidia abundant, especially at the stipe apex, in tufts or more sparsely distributed down the stipe, cylindrical and curved or flexuous, often with irregular outgrowths, simple to forked, sometimes capped with a large drop of gelatinous matter.
Mycena clavata is a member of sect. Hiemales Konrad & Maubl. subsect. Omphaliariae Kühner
ex Maas Geest. It is closely related to the most common species of the
subsection - Mycena speirea. Horak (2005) treated them as synonyms, but that is not correct. M. clavata can easily be separated from the latter on account of:
- the shape of the spores (M. speirea – ellipsoid to amygdaliform, 7.5–11 × 4.5—5.8 μm, qav ~ 1.9; M. clavata – broadly ellipsoid to subglobose, qav ~ 1.3)
- the shape of the cheilocystidia (M. speirea – mostly subcylindrical; M. clavata – mostly fusiform or lageniform, apically passing into a slender neck)
- the hyphae of the pileipellis (more branched in M. clavata, and with some of the diverticulae elongated into projecting pileocystidia-like hairs)
- the character of pigmentation in lower layers of the pileipellis and pileitrama – hypoderm (M. clavata –incrusting; M. speirea – intracellular)
The close affinity between M. clavata and M. phaeophylla has been mentioned a few times in the literature. Redhead (1986) was the first to point out that Mycena phaeophylla might be conspecific with M. clavata and put this name among synonyms of the latter, but with a question mark. Maas Geesteranus (1991: 388-389), however,
maintained them as different, although with rather weak arguments. He concluded that "Still further collections both from Europe
and North America will be needed before a concencus can be
reached". Ronikier and Aronsen (2007) studied 35 European collections, including the type of M. phaeophylla, and demonstrated that M. clavata and M. phaeophylla are conspecific indeed.
Redhead (2016) transfered it to the new genus Phloeomana
Mycena clavata is characterized by brown colours of pileus and stipe, arcuate, long decurrent lamellae, broadly ellipsoid to subglobose, nonamyloid spores, sub-cylindrical, fusiform to lageniform cheilocystidia with a slender neck which is often capped with a large drop of gelatinous matter, absence of true pleurocystidia, very branched hyphae of the pileipellis often with projecting, pileocystidia-like hairs, hyphae of hypoderm distinctly incrusted with brown pigment, and smooth hyphae of the cortical layer of the stipe with more or less cylindrical, flexuous caulocystidia often capped with a large drop of gelatinous matter.
Elborne and Læssøe (1982) noticed that the spores of their 2-spored collection of 'Mycena phaeophylla' were not completely smooth. They described the surface as covered with spots where the spore wall is thinner, giving it an appearance of being covered by small holes. This character is nicely demonstrated in the type collection (4-spored) under SEM.