Homophron spadiceum

Homophron spadiceum (P. Kumm.) Örstadius & E. Larss., in Örstadius et al., Mycological Progress 14 (5/25): 35 (2015)

Pileus 25–120 mm, convex, with inflexed margin, becoming plane, sometimes wavy, at first dark reddish brown, red brown (Mu. 2.5YR 3/4-4/4, 5YR 4/4), sometimes striate at margin, faintly hygrophanous, at maturity or when drying fading to pale ochraceous brown, flesh-coloured or pink (Mu. 5YR 5/8- 8/4, 7.5YR 8/4), at margin covered with minute hairs (lens); veil absent. Gills adnate, very crowded, L=60–82, when young very pale brown (Mu. 10YR 8/3), then brown with red tinges (Mu. 5YR 5/4, 7.5YR 5/4-5/6) and with a slightly flocculose edge. Stem 25–100×3–12 mm, rigid, equal or slightly thickened towards base, pale brown, flocculose at apex or half-way down, fibrillose below. Context rather firm. Taste mild and smell pleasant. Spore print dark reddish brown (Mu. 5YR 3/3).

Basidiospores 6.5–11 × 4–5.5 μm, av. 7.2–10.3×4.1–5.3 μm, Qav. = 1.7–1.9, ovoid, oblong, or subcylindrical, sometimes irregular in outline, in profile sometimes phaseoliform, rarely amygdaloid, thin-walled, very pale brown (Mu. 10YR 8/4), germ pore absent or rarely indistinct. Basidia 4-spored, 16–36×6–8 μm. Pleurocystidia 30–80 × 10–24 μm, lageniform, fusiform to conical, often rostrate with apex covered with crystals, wall up to 3 μm thick near apex, yellow or not, abundant, rarely rather scattered. Cheilocystidia of two types: A: 40–85 × 8– 22 μm, similar to pleurocystidia, scattered to abundant, B: 30–90 × 6–28 μm, clavate, utriform or cylindrical, scattered or rarely numerous. Caulocystidia present at apex and similar to shape of cheilocystidia. Hairs at cap margin originating from globose cells of pileipellis, septate or not; terminal cells of the hairs 40–180 × 6– 18 μm, versiform, cylindrical, clavate, lageniform etc., rarely similar to pleurocystidia. Pileipellis a hymeniderm with transition to a paraderm of 12–40 μm wide cells; pileitrama of moderately pigmented hyphae, rarely incrusted; hymenophoral trama of membranal pigmented hyphae. Clamps present on stem hyphae.

Habitat and distribution: Usually caespitose around deciduous trees and conifers, both stumps and at the base of living trees, e.g., Abies pinsapo, Acacia xanthophloea, Aesculus, Alnus, Bambusa, Betula, Castanea, Fagus, Morus alba, Picea, Pinus, Populus, Quercus faginea, and Ulmus; known from many countries in and outside Europe.

Index Fungorum number: IF811631

Notes: The species is distinguished by the absence of veil, hairy cap margin, very pale spores, and caespitose growth. Moreover, the rostrate cystidia are often thick walled and provided with crystals. H. cernuum differs in having paler basidiomata, smaller and darker spores, and obtuse cystidia.