Name: Gymnopilus bellulus
Author: (Peck) Murrill
Citation: N. Amer. Fl. (New York) 10(3): 200 (1917)
Deprecated Synonyms: Gymnopilus microsporus (Singer) Singer
Misspellings: Gymnopus microsporus (Peck) Murrill
Locality: New York, on decaying Hemlock
Rapid English Description: https://www.biodiversitylibrary.org/...
Characteristics in brief: Fruitbodies small, pileus 5–25 mm, hemisphaerical, conical-convex to convex, surface not glossy (mat) or slightly lustrous, smooth to fine- ly rugulose, but under lens distinctly tomentose-rugulose to finely rugulose-rugged, rusty orange to rusty brown with or- ange tinge, margin paler, yellow to yellow-ochre, lamellae deep yellow, then yellow-brown to yellow-rusty, stipe 10–35 × 1–3 mm, yellow-rusty in the upper part, towards the base yellow-brown, ochre-brown to rusty brown, surface pale yellow, yellow to yellow-rusty fibrillose-tomentose, taste bitter, spores small, mostly 4.5–6.0 × 3.0–3.5 μm, E = (1.3–)1.4–1.9(–2.0), Q = 1.63, ellipsoid to amygdaliform- ellipsoid with a distinct suprahilar depression, medium to coarsely verrucose, cheilocystidia narrowly lageniform with more or less prominent globose head which is not sharply separated from the neck, hyphae on pileus and stipe surface with clavate terminal elements up to 14 μm broad. Growing on strongly decayed wood (especially trunks) of conifers in natural or near-natural forests, preferably in the mountains.
Description: Fruitbodies growing individually or in small groups, never caespitose. Pileus 5–25 mm, hemis- phaerical to conical-hemisphaerical with inflexed margin when young, then campanulate-convex, conical-convex to convex, sometimes with a low broad umbo, margin some- what overlapping lamellae, at most slightly hygrophanous but mostly dry, not translucently striate, surface not glossy or only slightly lustrous, smooth to finely rugulose but un- der lens distinctly tomentose-rugulose to finely rugulose- rugged, not scaly, colour rusty orange to rusty brown (6D8), mostly with orange tinge, margin paler, yellow, yellow- rusty or yellow-ochre. Lamellae crowded, L = 22–30, l =
1–3, 2–4 mm high, more or less ventricose, near stipe emarginate and decurrent with a small tooth, at first pale yellow, then deep yellow, at maturity yellow-brown to yel- low-rusty, edge concolorous. Stipe 10–35 × 1–3 mm, base sometimes slightly bulbous, cylindrical, often curved, at first with pale yellow cortinoid traces of velum (towards pileus margin), soon disappearing, ground colour yellow- rusty in upper part, towards the base yellow-brown, ochre- brown to rusty brown, surface pale yellow, yellow to yellow-rusty fibrillose-tomentose, base sometimes whitish tomentose. Odour indistinct. Taste distinctly bitter.
Spores small, 4.5–6.0(–6.5) ×3.0–3.5(–4.0) μm, E = (1.3–)1.4–1.9(–2.0), Q = 1.63, yellow to rusty yellow in KOH, ellipsoid, amygdaliform-ellipsoid to ovoid ellipsoid in front view, ellipsoid to amygdaliform-ellipsoid with distinct suprahilar depression in side view, wall rusty brown, medium to coarsely verrucose, without suprahilar disc, slightly dextri- noid (with pale reddish brown tinge in Melzer’s reagent), ma- ture spores acyanophilous or only slightly cyanophilous, immature ones or those with a broken wall distinctly cyanophilous. Basidia 4(2–)-spored, 16–24 × 5–6 μm, cylin- drical to narrowly clavate with median constriction. Basidioles 16–18 × 5 μm, narrowly clavate. Cheilocystidia numerous, rarely intermixed with basidiolae and basidia, small, (16–)20–26 × 4–6 μm, narrowly lageniform with inflated basal part, long cylindrical neck (1.5–2.5 μm) and more or less prominent globose head (2–3.5(–5) μm) but head not sharply divided from the neck, sometimes also without head, thin- walled, hyaline. Pleurocystidia absent. Lamellar trama regu- lar, of densely arranged hyphae 4–16 μm broad, cells cylindrical or slightly fusiform, with yellow membranal pig- ment, trama completely pale yellow, subhymenium thin, of densely arranged hyphae. Pileus cuticle (section) a cutis of densely arranged parallel hyphae 3–8 μm broad, cells cylin- drical or slightly inflated, with rusty brown incrustations, en- tire layer yellow- to rusty brown, in scalp covered with a loose net of interwoven cylindrical hyphae (veil hyphae?) 3–13 μm broad with distinctly clavate terminal elements up to 14 μm broad, rusty brown incrusted (in a ”tiger” pattern), pileocys- tidia resembling cheilocystidia not observed. Stipe cuticle a cutis of densely arranged cylindrical hyphae 3–8 μm broad, cells rusty brown incrusted, terminal elements sometimes slightly capitate, this layer covered with loosely arranged pro- truding and curved hyphae (veil hyphae?), locally forming nests of interwoven hyphae 3–6 μm broad, rusty brown in- crusted, with distinctly clavate to sphaeropedunculate terminal elements up to 12 μm broad, caulocystidia rare, resembling cheilocystidia, lageniform or cylindrical with capitate head. Clamp connections present in all tissues. Fragments of lamellae exuding yellow pigment when mounted in KOH.
Fructification: July – October.
Ecology: Based on data from the Czech Republic, Gymnopilus bellulus is a saprophyte growing on thick fall- en trunks of Abies alba and Picea abies. The trunks are in later stages of decay characterised by the absence of bark, soft wood and mostly by the presence of moss covering. Ex- cept for conifers, there are also rare finds from wood of Fa- gus. All my collections from the Czech Republic as well as the herbarium specimens I have studied from this area orig- inate from natural to near-natural forests mostly designated as protected areas. A first type are so-called “mixed moun- tainous forests” composed of Fagus, Picea and Abies (typi- cal example: the “Boubínský prales” and “Žofínský prales” virgin forests) with admixture of Acer pseudoplatanus. Another habitat of G. bellulus is represented by natural mountainous Picea abies forests (climax spruce forests). In both habitats, G. bellulus grows only at sites with a rich presence of fallen trunks of old thick trees. This means that the species is lacking in cultural forests where all fallen trunks are removed. Concerning altitude, G. bellulus grows in the montane to supramontane zone (730–1340 m a.s.l., see collections studied).
I have also studied collections from Slovakia, Austria, Ukraine and Italy. In all cases, the data on ecology were similar (growth in natural to near-natural mountainous forests on wood of Picea or Abies). Also occurrence on Larix and Pinus cembra are reported by Breitenbach et Kränzlin (2000) and on Taxus by Orton (1993). Preference of G. bellulus for mountainous areas is also confirmed by a map by Krieglsteiner (1991) from Germany which clearly shows that the species grows there in the mountains only. On the other hand, Orton (1993) reports finds from Great Britain which are from lowlands. In accordance with my data, Høiland (1990) also writes that G. bellulus is “confined to mature or even virgin forest types” (to damp shady Picea forests in Norway).
Distribution: In the Czech Republic, Gymnopilus bellulus is documented from several mountain ranges (Šu- mava, Novohradské hory, Krkonoše, Beskydy). Generally, it is a rare species which is, however, typical and scattered in appropriate locations (see Ecology). Its records in suitable habitats of some other mountains are to be expected (e.g. Je- seníky, Králický Sněžník, etc.). The species is also known from the Carpathians in Slovakia and Ukraine (see Škubla 2003 and the collections studied). In Europe, it is further known from e.g. Italy, Switzerland (Breitenbach et Kränzlin 2000), Germany (Krieglsteiner 1991), Austria (Keller et Moser 2001) and France (e.g. Josserand 1948, Bon et Roux 2002), mostly from the Alps, but also from the Massif Cen- tral, Jura, Schwarzwald, Schwäbische and Frankische Alb. Except for the mountains, it is rarely found in lowlands (e.g. France, Great Britain, see Bon et Roux 2002, Orton 1993). In Scandinavia, G. bellulus is reported only from Norway (Høiland 1990). The species seems to be rare everywhere.
D i s c u s s i o n : Gymnopilus bellulus is well distinguish- able according to its small fruitbodies having relatively bright colours (pileus with orange tinge, lamellae at first deep yellow), bitter taste, small spores with distinct suprahi- lar depression, coarse ornamentation and length/width ratio mostly 1.4–1.9, small lageniform cheilocystidia with more or less distinct head and other characters summarised in the paragraph “Characteristics in brief”. Gymnopilus josse- randii also has small fruitbodies and small spores but it dif- fers in the characters discussed under that species.
- THE GENUS GYMNOPILUS (FUNGI, AGARICALES) IN THE CZECH REPUBLIC WITH RESPECT TO COLLECTIONS FROM OTHER EUROPEAN COUNTRIES