Growing solitary or in small groups among
vegetable debris under various deciduous trees but also
on fallen needles in Picea woods on calcareous
soil. In Europe it grows typically under Fagus
but in Norway it had mainly been found under Alnus
until it was collected under Fagus in Vestfold
2000. Listed as vulnerable
(VU) in the Norwegian Red List (2021). Autumn.
mm across, hemispherical to campanulate, becoming plano-convex,
shallowly sulcate, translucent-striate, hygrophanous, glabrous,
slightlylubricous when moist, date brown to pale dingy purplish
brown or pale lilaceous brown, from centre outwards drying
pale ochraceous or beige, with or without a pinkish shade.
Odour strong, raphanoid. Taste
similar. Lamellae 29-50 reaching
the stipe, ascending, becoming horizontal, at first narrowly
adnate or emarginate, then adnate to decurrent with a tooth,
smooth to transversely ribbed, dorsally intervenose, pale
lilaceous grey-brown, pale purplish brown, densely punctate
by minute, dark purplish brown dots (pleurocystidia), the
edge crenulate, dark purplish brown. Stipe
25-80 x 2-8 mm, hollow, fragile to firm, equal or somewhat
broadened downwards, straight, curved below, terete or laterally
compressed, coarselly fibrillose or even floccose, whitish
with slight yellowish, brownish or lilaceous tint, lenghtwise
striate by dark purplish brown fibrils, the base densely
slender-clavate, 4-spored. Spores
6-7.5(-8) x 3.1-4.1(-4.5) µm, Q 1.7-2.1, Qav ~ 1.9-2, pip-shaped, smooth, amyloid. Cheilocystidia
40-70 x 6-14 µm, mostly occuring mixed with the basidia,
but often very much protruding, and then locally forming
a sterile band, fusiform, smooth, with purplish
brown contents. Pleurocystidia
numerous, similar, with purplish brown contents. Hyphae
of the pileipellis 1.5-4.5 µm wide, smooth. Hyphae
of the cortical layer of the stipe 2.5-3.5 µm wide, smooth,
terminal cells 2-8 µm wide, cylindrical, simple or apically somewhat
branched. Clamps present in all tissues.
Mycena pelianthina is easily recognized
as a member of sect. Calodontes on account of the large size,
the purplish or violaceous tints, and the raphanoid odour.
Within this section it is placed in subsection Marginatae
J. E. Lange together with M. lammiensis
and M. rutilantiformis (Murrill) Murrill because
of the intensely coloured lamellar edge. The latter has
only been recorded from the United States. Redhead &
al. (2001) transferred Mycena pelianthina to the
genus Prunulus, a point of view that has not been
followed at this web site.
Harmaja (1985) described the until then
unknown species M.
lammiensis from Finland under
Alnus incana (and more rarely Picea abies).
It shares many features with M. pelianthina, like
the violaceous tints, the raphanoid smell, and the dark
violet lamellar edge. Microscopically the two species are
quite similar too, the only distinct difference being the
spore size. In M. pelianthina the spores rarely
are more than 4 µm broad, while in M. lammiensis
they are almost always broader than 4 µm. (According
to my measurements (6.0-)7.5-9.0 x (3.5-)4.0-5.0 µm).
The shape of the spores may be somewhat different too. In
M. pelianthina the spores are somewhat narrowly
pip-shaped, while in M. lammiensis they are pip-shaped
to somewhat cylindrical. This is, however, hardly a distinct
specific character. Harmaja claimed that the
cystidia of M. lammiensis were narrower
than the counterparts in M.
pelianthina, and that they had longer
and narrower necks. Although the outer measurements do not
differ much, my impression is that Harmaja is right on this
point. The cheilocystidia generally seem to be narrower
and with narrower and longer necks in M. lammiensis.
Another difference is that the cheilocystidia are much more
protruding in M. lammiensis than the counterparts
in M. pelianthina.
It is not clear to me whether the colour of
the pileus is different between the two species. In Mycena
pelianthina the colour is date brown to pale brown
with purplish to violaceous tinges, drying to pale ochraceous
or beige, with or without a pinkish shade. The descriptions
of M. lammiensis suggest a more dingy lilac colour,
which is turning more brownish with age. The blackening
process when drying seems to be similar in both species.
Harmaja (1985) and Maas Geesteranus (1992) discussed the very slight differences between M.
lammiensis and the American species M. rutilantiformis,
and concluded somewhat hesitantly that M. lammiensis
is a species in its own right.
Mycena lammiensis is known from 15 collections in Finland and red listed as Near Threatened (NT) (Finnish Biodiversity Information Facility 2023). An interesting question is if the Norwegian
collections of M. pelianthina, collected under
Alnus, from central and Northern parts of the country
actually would prove to represent M. lammiensis, as suggested by Harmaja (2002: 25).
Examination of three collections from the herbarium in Oslo,
and five collections from Tromsø, however, showed
without doubt that they are M. pelianthina. This has been cofirmed by sequences in the Norwegian Barcoding Project (NorBOL). However, in 2021 M. lammiensis was collected for the first time in Norway (see M. lammiensis).
I will express my thanks to the authorities
of the herbarium in Helsinki for the loan of the holotype
of M. lammiensis and an additional collection from
Turku (Leg. S. Huhtinen, 30 Aug. 1985). I am also grateful
for the loan of several collections of M. pelianthina
from the herbaria in Oslo and Tromsø.
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