Mycena viscosa Secr. ex Maire

Bull. Soc. mycol. Fr. 26: 162 (1910)

VESTFOLD, Færder, Tjøme, Rød/Dirhue,
2. November 2021, leg. Bjarke Anderson and Arne Aronsen.


Scattered to subfasciculate on decayed conifer stumps and fallen needles of conifers (Picea), generally near the base of trees. Widespread in the area. Fairly common in Norway but apparently more rare in the north.

Pileus 1.5-2.5 (-3.5) mm across, conical, campanulate, parabolical to convex, weakly umbonate, viscid, covered with a separable, elastic-tough pellicle, sulcate, translucent-striate, fairly pale grey to dark grey-brown, or olive-brown, staining with red-brown spots and finally becoming entirely red-brown. Odour said to be of rancid candle wax (in former times made of sheep fat), farinaceous or like leather. Taste mild or rancid-soapy. Gills ascending, narrowly adnate, decurrent with a short tooth, at first white, then grey or somewhat flesh-coloured, the edge paler, gelatinized, separable as a tough, elastic thread. Stipe 50-100 x 1-3 mm, viscid, citrine or yellow, turning red-brown from the base.

Basidia [size], 4-spored. Spores 8-10 x 6-8 mm, broadly ellipsoid to subglobose, Q 1.2-1.4, Qav 1.3, smooth, amyloid. Cheilocystidia 10-27 x 7-10 mm, forming a sterile band, embedded in gelatinous matter, clavate, subcylindrical to subglobose, simple to branched, covered with relatively few, unevenly spaced, fairly coarse, simple to furcate or branched, cylindrical excrescences 2.5-12 x 1-2 mm. Pleurocystidia absent. Hyphae of the pileipellis 1-2 mm wide, embedded in gelatinous matter, branched, anastomosing, mostly smooth but especially the outer hyphae densely diverticulate. Hyphae of the stipitipellis 1-3 mm wide, smooth, embedded in gelatinous matter; terminal cells 10-23 x 5-10 mm, clavate to irregularly shaped, simple to branched, sparsely to very densely covered with fairly coarse, rather short, simple to furcate, cylindrical excrescences 2-12 mm long. Clamps present in all tissues.

Mycena viscosa has been regarded as a separate species by some mycologists (e. g. Maire 1910, Hintikka 1963, Moser 1982, von Bonsdorff et al. 2014), while others have treated it as a variety of Mycena epipterygia (Maas Geesteranus 1989, Ludwig 2012), or within the variation of the type variety (Aronsen & Læssøe 2016, Emmet et al. 2018). Recent phylogenetic analyses of sequences obtained in the Norwegian Barcode Project (NorBOL) show that it is a species in its own right.

Salient features of this taxon are the greyish to grey-brown cap without any yellow hues in contrast to the yellow stipe, presence of red-brown spots, a pronounced rancid smell, broadly ellipsoid to subglobose spores 8-10 x 6-8 mm, and growth on coniferous wood. Maas Geesteranus (1989) claimed that the terminal cells of the cortical layer of the stipe could be used to differentiate between this taxon and Mycena epipterygia var. epipterygia. According to his observations the excrescences of the terminal cells of var. viscosa are shorter (up to ca. 5 µm long), while they are longer (up to 12.5 µm) in var. epipterygia. We have not been able to confirm this, although they seem to be generally short in M. viscosa. Besides, var. epipterygia has narrower spores (Q 1.8-2.2). Maas Geesteranus (1989) measured smaller spores (8.1-8.5 x 5.4-6.3 µm) but indicated that they possibly were immature. Maire’s measurements were 8-12 x 6-8 µm (Maire 1910) and more in accordance with our measurements.

Since the cystidia in this species are embedded in gelatinous matter at the lamellar edge, they can be hard to find. The large ‘cystidia’ depicted by Maire (1910) is probably something else, and possibly he did not observe the real cheilocystidia.

Peck (1913: 28-29) described Mycena splendidipes, which Kühner (1938) reduced to the synonymy of M. epipterygia var. viscosa without a word of explanation. Maas Geesteranus (1989) treated it as a separate variety: Mycena epipterygia var. splendidipes on account of the colour of the pileus (yellow below) and different aspect of both the cheilocystidia and the terminal cells of the hyphae of the stipitipellis.

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