Mycena polyadelpha (Lasch) Kühner

Encyclop. Mycol. 10: 262 (1938)

© A. Aronsen
VESTFOLD, Nøtterøy, Torød 20 Oct. 2004

On fallen, decaying leaves of Quercus. Also reported on leaves of Fagus. Late autumn.

Pileus 0.5-2.5 (-4) mm across, hemispherical, parabolical or convex, sometimes centrally somewhat depressed, sulcate, hardly striate, puberulous or granular puberulous, more or less glabrescent, very thin, translucent in parts, white. Lamellae (0-)4-8(-11) reaching the stipe, subhorizontal to slightly arcuate, often very narrow, broadly adnate but not always reaching the stipe, the edge straight to concave, white. Stipe 5-50 x 0.1-0.2 mm, filiform, flexuous, equal, pruinose, glabrescent for the greater part, but puberulous at the base, watery white to white, occasionally somewhat brownish at the base, insititious. Odour none.

Basidia 15-18 x 8-10 µm, broadly clavate, 2-spored or 4-spored. Spores (4-spored) 9-11.8 x 3.5-5 μm, Q = 1.9-2.4 or (2-spored) 10-13.5 x 3.5-5 µm, Q = 2.2-3.2, Qav ≈ 2.6, elongated pip-shaped, sometimes almost cylindrical, smooth, amyloid. Cheilocystidia 15-27 x 8-15.5 μm, clavate, obpyriform, subcylindrical to subglobose, covered with numerous, evenly spaced, warts or short excrescences 1-2 µm long. Pleurocystidia absent. Lamellar trama dextrinoid, vinescent in Melzer's reagent. Hyphae of the pileipellis 2.5-20 μm wide, densely covered with warts, with more or less inflated terminal celles. Hyphae of the cortical layer of the stipe 1.8-5 µm wide, covered with cylindrical excrescences 1-5 µm long. Caulocystidia 5-16 µm wide, clavate, covered with narrow, cylindrical excrescences. Clamp connections present in all tissues in 4-spored form; absent in 2-spored form.

Mycena polyadelpha has usually been stated to be four-spored, but Maas Geesteranus (1983: 396) described a two-spored form. Later (Maas Geesteranus 1986: 173) he indicated that two-spored forms are perhaps less rare than originally thought. The Norwegian collections seem to be mostly 2-spored.

Mycena polyadelpha is a member of sect. Polyadelphia, and is characterized by the small size, the white colour of the entire carpophore, the distant, broadly adnate lamellae, the cheilocystidia covered with warts, and the occurence on decaying oak leaves. It has been reported from leaves of Fagus too (Maas Geeateranus, 1986: 173), and then it may be confused with M. capillaris. There are only very slight differences between the two species. M. capillaris usually becomes greyish to pale greyish brown at the centre of the pileus, the lamellae are more narrowly adnate, the stipe is fairly dark grey-brown to blackish in very young specimens, and the spores are narrower. Whether the records on Fagus leaves really represent M. polyadelpha, should be investigated by molecular methods.

There are several species of this section growing on fallen Quercus leaves. M. bertaultiana Moreno & Heykoop, M. catalaunica Robich and M. smithiana Kühner are characterized by pinkish colours. M. quercus-ilicis Kühner is a species occuring in southern Europe. Among several things it differs from M. polyadelpha by having broadly pip-shaped to subglobose spores. M. querciphila Esteve-Raventós & Villarreal, known from Spain, differs in having a pale olive-yellow, yellowish-brown to dark olivaceous-grey pileus and smooth cheilocystidia. M. smithiana, usually with a pink colour on the cap, can occur in almost enyirely white forms, and then is very difficult to distinguish from M. polyadelpha.

Another tiny, white species growing on Quercus leaves is M. mucor. It is characterized by a stipe with a small basal disc, a separable, elastic pellicle, and cheilocystidia with fairly few, long excrescences.

Microphoto of the hyphae of the pileipellis

Microphotos of cheilocystidia

Microphoto of spores

Next image

Go to key to sect. Polyadelphia.

© A. Aronsen 2004

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© Arne Aronsen 2002-2023