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Description type:Original description 
Description:Pileus 3-6 cm broad, expanding to convex-depressed, soon plano-depressed becoming vase-shaped to shallow-infundibuliform, surface glabrous, viscid to slimy in moist weather, soon dry and shiny, concentrically rugulose on fresh, and finely plicate in drying, azonate, brownish gray (5E2-7F1) to grey dark brown (6F6) when young and fresh, later on dark brown (6F7-5F3), dark gray (1F1-3F1), blackish-brown (6F9), blackish grey (19G1) to blackish (5E3), depressed centre flat, finely velvety pruinose. Margin concolorous to the disc, rolled-up at first, rolled-out in age but still crumpled, lobed at maturity and when dry. Gills adnate-decurrent, crowded, up to 3 mm broad, gray (1E1) to pale grayish (2B1), upward half part paler than the lower part, powdery under a lens, lamellulae in many tiers, not forked. Stem 3.5-5 x 1-1.5 cm, cylindrical, solid, equal, sometimes more or less enlarged at the base, hollow, concolorous to the pileus at the lower part, and with the gills upwards, or dark gray (5F1-6F1), being covered by fine longitudinal striae, basal mycelium dense and whitish. Context soft, very thin, 2-4 mm, brownish gray (6E2), becoming gray (6D1) when drying, unchanging in contact with air and no reaction with KOH and FeSO4. Odor none. Taste unpleasant. Latex white, acrid, unchanging with air, or slightly fading to watery. Spore deposit whitish cream (4A3) to grayish (2E1).
Basidiospores 7.4-9.8 x 7.4-8 µm, Lm = 8.7 ± 0.6 µm, Wm = 7.6 ± 0.4 µm, Qm = 1.14, excluding ornamentation, globose to subglobose as seen in profile, at times short-ellipsoid, wall colourless to yellowish (2A3) in KOH, nonamyloid, ornamentation strongly amyloid, winged, composed of wings (ridges) with prominences 2-3 µm high, ridges often with split aspect, reticulum very reduced and fine lines often connecting the heavy bands, isolated warts absent between the wings, plage area small but distinctly amyloid, apiculus prominent and mostly oblique, 4-6 µm long. Basidia 47-88 x 8-15 µm (excluding the sterigmata), fusiform, broadly tapering at base, (2-)4-spored, sterigmata almost arcuate, up to 12 x 2.5 µm, mature basidia widely projecting up to 30 µm beyond the palisade, contents oily granular with one to four large droplets. Pleurocystidia: macrocystidia none, pseudocystidia rare, contents refractive, filamentous. Cheilocystidia abundant, 49-73 x 5-6 µm, fusiform, subcylindrical to subclavate, thin-walled, contents granular. Lactifer cystidia absent. Gill trama composed of subparallel, colourless, thin-walled, hyphae 3.5-6 µm broad, intermingled with numerous thin-walled, 3-8 µm broad, cylindrical, inflated to flexuous lactiferous hyphae having dense and colourless contents in KOH, no sphaerocystes present. Pileus trama heteromerous.
Pileipellis trichoderm-like, 40-80 µm thick, brown to yellowish brown (5E8), composed of 2.5-6 µm broad hyphae, irregularly inflated, simple septate, branched, thin-walled, bearing a turf of pileocystidia. Pileocystidia 95-160 x 4.5-6 µm, subcylindrical, slightly flexuous, at times moniliform, constricted towards the apices, colourless, thin-walled. Stipitipellis a modified trichoderm with lower cells of elements somewhat angular-inflated, forming a slightly distinct cellular layer in the aggregate, the end cells covered with a distinct but thin gelatinous layer (in KOH and in Melzer's), cell contents pale light brown (6D7) in KOH. Stem context consisting of 3-6 µm broad, subparallel hyphae, colourless, less branched with slightly inflated ends. Clamps absent in all tissues.
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