Gregarious to cespitose in grass near Juniperus
or on needles of Juniperus. Not yet found outside
the type locality, where it has been collected from three
different places. The type was found on needles of Juniperus
in a coastal area with scrub of Juniperus communis,
Prunus spinosa, and Rosa sp. Listed as
DD in the Norwegian red list (2021).
Pileus 10-40
mm across, parabolical to conical or campanulate, becoming
broadly convex to applanate, then often umbonate, sulcate
or not sulcate, very finely fibrillose (somewhat reminiscent
of the pileus surface of some species of Inocybe), especially
at the centre, translucent-striate, dry, slightly lubricous
when moist (with dirt sticking to the surface), shiny, very
dark sepia brown to black or even bluish black at the centre,
sepia brown farther outwards, fading to grey-brown with
age, margin straight to somewhat flaring with age, at first
almost white, turning brownish. Flesh thin, very dark under
the upper surface, paler farther below. Lamellae
16-24 reaching the stipe, tender, ascending, c. 2 mm broad,
ventricose, narrowly adnate, sometimes uncinate, thin and
smooth when young, much thickened, strongly veined or rugose,
and intervenose with age, at first white, then dark grey;
the edge convex, white to pale grey. Stipe
30-80 x 4-5 mm, stocky, hollow, terete or somewhat compressed
and fissured lengthwise, straight or somewhat curved, smooth,
at first conspicuously white-puberulous all over, glabrescent
for the greater part (except at the apex), slate-coloured,
dark bluish grey, particularly at the apex, gradually becoming
paler and turning somewhat more brownish, the base densely
covered with long, fairly coarse, somewhat woolly, white
fibrils. Odour nitrous, taste not recorded.
Basidia either 25-35
x 6.5-8 µm, slender-clavate, 2-spored and clampless
with sterigmata up to c. 8 µm long, or 30-45 x 8-9
µm, 4-spored and clamped. Spores (basidia
2-sp.) (7.6-)9.0-11.8(-14) x (5.0-)6.0-7.2(-8.5) µm, Q = 1.6-2.3, Qav ≈ 1.8, or
(basidia 4-sp.) 7.6-9.0 x 5.4-5.6 µm, pip-shaped (those
which are shorter and fairly broadly pip-shaped probably
being immature), smooth, amyloid. Cheilocystidia
20-60 x 7-16 µm, originally forming a sterile band
(lamellar edge homogeneous) but soon crowded out by vigoroulsy
developing younger generations of basidia, clavate to fusiform,
clampless (basidia 2-sp.) or clamped (basidia 4-sp.), smooth,
apically broadly rounded or mucronate, more rarely with
a longer, slender neck. Pleurocystidia
similar, scanty, unobtrusive. Lamellar trama dextrinoid, brownish vinescent
in Melzer's reagent. Hyphae
of the pileipellis 2.5-6.5 µm wide,
clampless or clamped, smooth. Hyphae
of the cortical layer of the stipe 1.5-4.5
µm wide, clampless or clamped, smooth, the terminal
cells (caulocystidia) 25-90 x 2-22.5 µm, cylindrical,
narrowly to broadly clavate, ellipsoid to more or less irregularly
shaped, simple or, more rarely, furcate, smooth. Clamps present in all tissues in 4-spored form, absent in 2-spored form.
Microphotos of cheilocystidia
Mycena ustalis is a member of the
large section Fragilipedes. It
is characterized by its very dark colour of the pileus,
a white-puberulous, slate grey stipe, and nitrous smell. Important microscopic
features are the smooth hyphae of the pileipellis and of
the cortical layer of the stipe, as well as the smooth ceilocystidia.
M. leptocephala generally has a paler cap, strongly diverticulate hyphae of the pileipellis, and variously shaped, often much inflated caulocystidia. M. austera is another dark, nitrous smelling species, which can be distinguished by large fusiform to lageniform cheilocystidia, diverticulate hyphae of the pileipellis with very prominent terminal cells, sparsely diverticulate hyphae of the stipitipellis. |
