Gymnopus fuscotramus

Gymnopus fuscotramus Mešić, Tkalčec & Chun Y. Deng

MycoBank number: MB 519324

Pileus 12–21 mm broad, campanulate, sometimes with applanate or slightly depressed center, sulcate almost to the center, weakly translucently striate when moist, hygrophanous, brownish incarnate to incarnate-brown when moist (from 10B4 to 11D5), pale incarnate on drying, with darker, mostly dark

red-brown to blackish-brown center, surface dull, dry. Lamellae free (without a collarium or pseudocollarium), distant (L = ca. 12, l = 1), ≤2 mm broad, ventricose, reaching the margin of the pileus or almost so, sometimes slightly intervenose, brownish incarnate, with entire, concolorous edge. Stipe 15–30 × 1–1.5 mm, subcylindrical, orange- to red-brown in the upper part, downward brown-black to black, entirely pale brown floccose-squamulose, dry, hollow, insititious, arising directly from substrate (not from rhizomorphs). Context grayish-brown and very thin in pileus, whitish in stipe medulla, concolorous with surface in stipe cortex. Smell and taste not recorded. Rhizomorphs abundant, filiform, unbranched, ≤135 mm long and ≤0.5 mm thick, glabrous, black, with black to black brown inner context, hollow, apex with white globule or tapering and concolorous. Spores [50/2/1] (6.7–)6.8–8.2–9.6(–9.8) × (3.0–)3.0–3.7–4.4(–4.8) μm, SD= 0.71 × 0.34, Q = 1.73–2.23–2.70, oblong to subcylindrical, in side view often amygdaliform or even lacrymoid, smooth, hyaline, thin-walled, non-amyloid, non-dextrinoid. Basidia 23–36 × 4.5–6 μm, narrowly clavate, (2)4-spored, thin-walled, hyaline, clamped. Basidioles narrowly clavate, cylindrical or fusoid. Lamellar edge sterile, composed of repent, diverticulate, hyaline

to gray-brown, 1.5–8 μm broad hyphae, with clusters of cheilocystidia. Cheilocystidia 20–60 × 5–15(–25) μm, subcylindrical to irregularly clavate with irregular finger- to knob-like projections or coralloid, thin- to moderately thick-walled (≤0.8 μm thick), hyaline to pale gray-brown. Pleurocystidia absent. Hymenophoral trama irregular, composed of 1–6(–8) μm broad, thin- to moderately thick-walled (≤1 μm thick), subhyaline to pale gray-brown (gray-brown in mass) hyphae, pigment intracellular. Pileipellis a subregular cutis composed of 1.5–10 μm broad, mostly thin-walled, less frequently

moderately thick-walled (≤0.8 μm thick), subhyaline to brown, mostly diverticulate hyphae, with occasional coralloid elements, dark brown pigment often coarsely encrusted. Pileal trama composed of pale gray-brown (graybrown in mass), non-gelatinized, thin- to moderately thick-walled (≤0.8 μm thick), 1–7 μm broad hyphae, pigment intracellular. Stipitipellis a cutis of parallel, 1.8–7 μm broad, brown hyphae with intracellular, sometimes also encrusted pigment. Caulocystidia very abundant, 5–100 × 4–12 μm, mostly cylindrical, subcylindrical or narrowly clavate, with obtuse apex, sometimes diverticulate, moderately thick-walled to thick-walled [walls 0.5–2(–2.5) μm thick], sometimes with one septa, often in groups, subhyaline to brown, with intracellular, sometimes also encrusted pigment. Stipe trama composed of parallel, thin- to thick-walled (≤1.2 μm thick), 2–10 μm broad hyphae, hyaline in stipe medulla. Clamp connections present and abundant in all tissues. Chemical reactions: all parts of basidioma non-amyloid and non-dextrinoid except hyphae in cortical layer of stipe and caulocystidia, which are dextrinoid (red-brown in Melzer’s reagent).

Habitat — In small clusters on a twig, in humid subtropical forest of Fagus longipetiolata and Castanopsis lamontii.

Distribution — Known only from the type locality in China.

Fig. 1 Phylogenetic tree based on the complete ITS rDNA region (ITS1, 5.8S rDNA, and ITS2), showing mean branch lengths of a 50 % majority-rule consensus tree from a Bayesian MCMC analysis. NJ, MP bootstrap values (>70%), and Bayesian PP values are given above nodes.