Mycena rosea (Schumach.) Gramberg

Iconogr. Gen. Pl. 1: 36 (1912)

© A. Aronsen 2010
VESTFOLD, Nøtterøy, Torød 12 Sept. 2010

Solitary to scattered, preferably under oak and beech, often on calcareous soil. Summer to autumn.

Pileus 25-60 mm across, convex to plane, more or less with a low umbo, sometimes with a depressed concentric zone, glabrous, "waxy", shallowly sulcate, translucent-striate, hygrophanous, dark to pale pink or lilaceous pink, pallescent with age and turning dingy yellow at the centre. Lamellae c. 30-40 reaching the stipe, ascending, emarginate, dorsally intervenose with age, pink. Stipe 60-100 x 4-10 mm, hollow, firm, generally widening towards the base, straight, sometimes curved below, terete, pruinose, innately fibrillose, white or pale pink, often yellowish below, the base more or less densely covered with long, coarse, whitish to yellowish fibrils.. Odour raphanoid.

Basidia 29-32 x 6-7 μm, slender-clavate, 4-spored, with sterigmata up to 5 μm long. Spores 7-8.5 x 4-5 μm, Q 1.5-1.9; Qav ≈ 1.7, pip-shaped, smooth, amyloid. Cheilocystidia 20-90 x 8-18(-36) μm, forming a sterile band, fusiform, clavate, spheropedunculate, short- or long-stalked, smooth. Pleurocystidia similar. Lamellar trama dextrinoid. Hyphae of the pileipellis 1.5-5 μm wide, smooth. Hyphae of the cortical layer of the stipe 2-3 μm wide, smooth, caulocystidia 55-160 x 3.5-22.5 μm, fusiform to cylindrical, smooth. Clamp connections present at all tissues.

Mycena rosea belongs to sect. Calodontes subsect. Purae together with M. diosma, M. dura, M. pura, and M. kuehneriana. It can be distinguished from the closely related M. pura on account of the pink colours but as pointed out by Maas Geesteranus (1989b: 500): "In spite of the fact that Mycena rosea, once shown, is easily distinguishable from M. pura already in the field, it is rather embarrassing to find that the differences are not readily translated into words and it is rather a surprise to learn that microscopically there is no difference between the two species." From my experience, M. rosea can be distinguished from M. pura by the +/- uniform pink colours and a more robust stature, including a widened stipe base.

In view of the great variability of Mycena pura, it would not be unnatural to regard M. rosea as a form or variety of M. pura. It seems, however, to be a broad acceptance for regarding them as separate species. The difference between the poisonous substances in either taxon (Kubička & Veselský 1978) is a strong point in favour of this conclusion. This is also supported by phylogenetic studies.

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© Arne Aronsen 2002-2023