Solitary, in small groups or subfasciculate
on moss-covered trunks of deciduous trees (e.g. Acer,
Fagus, Quercus). Common in the nemoral area, absent or rare in higher or more northern areas. In Norway rare, but rather frequent in Vestfold. Listed as NT
in The Norwegian Red List (2021).
mm, hemispherical, conical, campanulate to convex, dry,
sulcate, translucent-striate, pruinose, glabrescent, sometimes
at first bluish to bluish grey becoming brown, darker in
the centre, or dark blackish brown with bluish black centre,
fading to pale brown with the centre somewhat darker. Lamellae
15-22 reaching the stipe, ascending, narrowly adnate,
occasionally with a short decurrent tooth, white to grey-white
or sometimes pale brown, the edge paler, occasionally with
red spots. Stipe 10-65(-90) x 0.5-1.5
mm, equal, terete, hollow, straight to curved, pruinose,
glabrescent, somewhat cartilaginous, at first greyish brown
to brown with bluish apex, then grey-brown to dark brown,
exuding a watery-whitish fluid when cut; the base covered
with long, white fibrils. Flesh sometimes turning faintly
red when cut. Odour indistinctive. Also experienced as farinaceous-rancid.
Taste very bitter.
Basidia 22-28 x 8-11µm, clavate,
2-spored (rarely 4-spored), with plump sterigmata 7-10 µm long. Spores
(7.8-)9.5-12 x 6.5-8.5(-9.0) µm, Q 1.3-1.7, Qav ≈ 1.5, broadly ellipsoid,
smooth, amyloid. Cheilocystidia
20-66 x 8-19 µm, forming a sterile band, strikingly
variable, fusiform, smooth, sometimes narrowed into
a shorter or longer neck, or clavate, covered with few to numerous,
coarse, simple to branched, straight to curved or flexuous excrescences 3.5-11 x 1.5-2.5 µm, or all kinds of intermediate shapes. Pleurocystidia
numerous, fusiform, often longer than the cheilocystidia,
generally filled with refractive globules. Lamellar trama dextrinoid. Hyphae
of the pileipellis 1.5-3 µm wide, covered with more or less curved, simple to branched, cylindrical excrescences
3-10(-20) x 1-2 µm, which may form dense masses and tend to become somewhat
gelatinized. Hyphae of the cortical layer of
the stipe 1.5-3.5 µm wide, fairly sparsely
covered with cylindrical, simple to occasionally branched, straight to curved, excrescences 1.5-13.5 x 1.5-2.5 µm, terminal cells infrequent,
diverticulate. Clamp connections generally absent, but present in 4-spored form.
More microscopic figures.
Despite the many diagnostic characters, M. erubescens possibly often is overlooked and also at times misidentified. It can be confused with small specimens of M. polygramma and dark specimens of Phloeomana hiemalis. Neither of them has bitter taste nor is reddening in the stipe. Besides, the latter has smooth, fusiform to utriform cheilocystidia and inamyloid spores.
erubescens belongs to sect. Lactipedes, and is identified by:
- occurence on moss-covered trunks of deciduous
- bitter taste
- watery milky fluid in the stipe
- flesh more or less reddening when exposed to
- strikingly variable cheilocystidia
- fusiform pleurocystidia, often filled with refractive
- broadly pip-shaped spores