Characteristics in brief (macrocharacters and ecology are compiled from Høiland 1990, Orton 1993, Lud- wig 2001; microcharacters are based on a personal study of 2 collections from the Czech Republic): Fruitbodies small, pileus up to 30 mm, dirty yellow-brown, rusty brown to greyish brown, surface fibrillose-tomentose to tomentose-scaly, stipe finely floccose, fibrillose to fibrillose-scaly, taste completely mild, spores 7.2–9.2(–10.4) × 4.0–5.2 μm, narrow, amygdaliform to narrowly amygdaliform with prominent suprahilar depression in side view, moderately to coarsely verrucose, without suprahilar disc. Growing as a saprophyte on dry sandy soil, peaty soil, burnt soil, ash and charcoal in Picea or Pinus forests, very rare.
Description: I have not seen fresh fruitbodies in the field (the species is extremely rare in the Czech Republic). For recent descriptions see Høiland (1990: 276), Ludwig (2001: 158–159) and Orton (1960: 243–244, 1993: 69–70). The description of the macrocharacters published here is adopted from Høiland (1990).
Pileus 7–27 mm, convex, fibrillose felty or scaly with felty squamules, dirty yellow-brown, dirty red-brown, or greyish brown. Lamellae adnexed to adnate, bright yellow to orange yellow. Stipe 10–20 × 2–4 mm, fibrillose, brown, but more yellow towards the apex, with weak veil remnants. Flesh yellow, with mild taste. Superficially reminiscent of Cortinarius (Dermocybe) croceus.
The description of the microcharacters is based on a per- sonal study of the collections cited below. Spores 7.2–9.2(–10.4) × 4.0–5.2 μm, shape and size variable, amygdaliform to narrowly amygdaliform with prominent suprahilar depression in side view, in front view ellipsoid- amygdaliform to narrowly amygdaliform with acute ends, wall rusty brown, medium to roughly verrucose, without suprahilar disc, mature spores dextrinoid, immature ones not dextrinoid. Basidia 20–24 × 5.5–6.5 μm, cylindrical to narrowly clavate, with slight median constriction, 4(2)–spored. Cheilocystidia 20–32 × 6–8 μm, variable in shape: narrowly lageniform-fusiform, brodly lageniform, utriform, fusiform-cylindrical, apex obtuse to capitate, neck 2–3 μm broad, head about 5 μm broad, some of them with slightly thickened wall (up to 0.8 μm), hyaline or filled with yellow-rusty pigment. Pleurocystidia rare, narrowly utri- form. Lamellar trama regular, hyphae (4–)5.5–12 μm broad, with rusty brown content or incrustations. Pileus cuticle (section) a cutis, 1-layered, thin, of densely arranged paral- lel to slightly interwoven hyphae (4–)6–10 μm broad, strongly yellow-brown incrusted, in scalp covered with nests or cords of veil hyphae, 5.5–13.5 μm broad, cells cylindrical, with rusty brown incrustations arranged in a ”zebra” to ”tiger” pattern, terminal elements narrowly clavate, pileocystidia not observed. Stipe cuticle a cutis of cylindrical hyphae 5–7 μm broad, slightly pigmented, caulocystidia absent. Clamp connections present in all tis- sues.
Fructification: The only two collections from the Czech Republic are from the end of September and begin- ning of October. However, the species is found from June to October (Høiland 1990, Ludwig 2001).
Ecology: In the CR, one find is from a sparse young stand of Pinus sylvestris on dry sandy soil covered with lichens and the other from a clearing where a Pinus forest was before, on naked soil in the vicinity of a burnt place. The following substrates and habitats are given by various European authors (e.g. Høiland 1990, Orton 1993, Ludwig 2001): naked soil (usually dry sandy soil), peaty soil, burnt soil, ash and charcoal, sawdust and ash; in Picea or Pinus forests.
Distribution: Gymnopilus decipiens is known from most European countries but it is extremely rare elsewhere. In the Czech Republic, only two localities are known in southern Bohemia.
Discussion: Gymnopilus decipiens is typical by its growth on soil or on burnt substrates and by other charac- ters summarised in the paragraph ”Characteristics in brief”. Gymnopilus odini has a similar ecology but differs by a more vividly coloured pileus (orange red-brown) with an al- most smooth surface (at most finely fibrillose-scaly), bitter- ish taste and slightly shorter spores measuring (6–)6.5–7.5(–8.5) × (3.5–)4.0–4.8(–5.5) μm (Høiland 1990, Orton 1993).
Bon et Roux (2002) mention another Gymnopilus species growing on soil or burnt substrates in Europe (based on material especially from France): Gymnopilus pseudo- fulgens Romagn. (Romagnesi 1979), a carbonicolous species distinguished by a farinaceous to bitterish taste, rather large spores with a distinctly delimited suprahilar disc and “subpore” at apex, and Gymnopilus humicola Hard. ex Singer (on humus, bitter taste, pileus 3–5 cm, rusty dotted on ochraceous ground, yellow stipe, spores 7–8.5(–9) × 4–5 μm). These species are not known from Central Europe.
Finally, Ludwig (2000: fig. 31.12., 2001: p. 159–160) describes a “small, undeterminable species found on fire place, coming near G. decipiens, but differing by bitter taste (not farinaceous) and clearly smaller and broader spores”. However, he had only one fruitbody at hand so this find is waiting for evaluation until more material is available.
- THE GENUS GYMNOPILUS (FUNGI, AGARICALES) IN THE CZECH REPUBLIC WITH RESPECT TO COLLECTIONS FROM OTHER EUROPEAN COUNTRIES