Summary:
Features include 1) a convex - bell-shaped cap that is glutinous, and tawny to dark brown (carbonized blackish brown when dried), 2) young gills that are pinkish to pale rosy lilac, 3) a stem that is slender, shiny, drab to violet, fibrillose-stuffed to partially hollow, and rooting (pseudorhiza vertical-monopodial and fleshy), 4) spores that are lemon-shaped with an apical beak and finely roughened (marbled), 5) cheilocystidia that are clavate and thin-walled, 6) a cap cuticle that is 2-layered with a thick, gelatinous, colorless suprapellis overlying an orange subpellis, and 7) absent clamp connections. Phaeocollybia rifflipes is a member of the Phaeocollybia festiva complex which comprises small to moderately sized, relatively fragile, relatively odorless/tasteless fruitbodies with conic-bellshaped, glutinous caps, rosy to violet gills, spores that are medium to large (7-9(10) x 4-5.3 microns), limoniform to fusiform (naviculate), and roughened (rugulose-ornamented, best described as marbled), cheilocystidia that are thin-walled, +/- clavate, and emanate from the gill trama, and highly gelatinized tissues lacking clamp connections (from Norvell(5) and Norvell(11)). See SIMILAR to differentiate the other Pacific Northwest species in the Phaeocollybia festiva complex which are P. lilacifolia and P. fallax. The description is derived from Norvell(5) except where noted. It is uncommon to rare (Norvell(5)).

Cap:
(1)2-4(5.5)cm across, at first conic-convex with acute papillate umbo, soon conic - bell-shaped "with low broad umbo and incurved to downturned margin with long-inrolled edge"; "when young tawny to dark orange-brown overall or with darker disc", and red-brown to yellow-brown edge, when old more or less uniformly dark brown with a dark green-brown edge, when dried carbonized black-brown; bald, viscid to heavily glutinous, (Norvell(5)), about 2-6cm across; hygrophanous, "heavily glutinous, smooth, bald, faintly striate"; dried cap dark brassy metallic to dull blackish brown and edges often noticeably striate, (Norvell(11))

Flesh:
0.1-0.4cm thick at the disc, thinning abruptly over gills; often consumed by insects; pallid or buff when young, when old or after exposure brown or drab; in stem stuffed, with 0.15-0.2cm thick cartilaginous cortex surrounding firm (packed when young) to spongy (when old) pallid flesh, the flesh easily compressed when water-soaked and when old often insect-infested, (Norvell(5)), stem when young stuffed with firmly packed fibrils that may loosen and split to form a central hollow, the pallid pith darkening when waterlogged and often insect-infested, cartilaginous rind about 0.15cm thick, (Norvell(11))

Gills:
free to narrowly attached, subcrowded, gills plus subgills -15 per centimeter at edge, 12 at midpoint, 3-5 tiers of subgills irregularly interspersed, 0.3-0.5cm broad, ventricose; "pale violet or bluish gray when young" [also given in a summary as "pale violet gray to dull pinkish brown"], dulling as maturing, when old obscured by dark brown spores; edges even at first, soon uneven to eroded, (Norvell(5)), pinkish, pale rosy lilac, or pale bluish gray when young, darkening to drab brown, "Special emphasis is now placed on the pinkish to rosy lilac gill coloration, previously incorrectly described as more bluish violet in hue.", (Norvell(11))

Stem:
generally 3-5cm long above the ground, combined length with pseudorhiza up to 16.5cm, 0.4-0.9(1.2)cm wide at top of stem, "either widening slightly to ground level or tapering evenly to pseudorhizal origin", stem central to slightly eccentric [off-center], round in cross-section or compressed, fleshy, fibrillose-stuffed to hollow; generally with drab to smoky brown tones at top, increasingly darkening toward ground level; "smooth and shiny beneath relatively dense fibrillose patches"; pseudorhiza unbranched, vertical-monopodial, fleshy-cartilaginous, with dark red-brown upper part arising from narrow, curled / nippled, brownish drab origin, (Norvell(5)), at top when young pale drab to violet, increasingly darkening toward ground level; pseudorhiza about 2/3 of overall length, continuous with stem and gradually tapering to a narrow curled or ''nippled'' origin, (Norvell(11))

Veil:
primordial sheath remnants when present as (usually) scattered, short, fibrillose patches on stem apex and / or (occasionally) fibrils overlying gills, (Norvell(5)), veil evident as scattered to abundant short fibrillose patches on stem apex and occasional scattered fibrils overlying young gills, color brownish drab, (Norvell(11))

Odor:
"not distinctive to slightly floral", (Norvell(5)), "not distinctive to obscurely complex with floral and pungent chemical components", (Norvell(11))

Taste:
"mild or (occasionally) faintly bitter"

Microscopic spores:
spores 7-7.5 x 4-4.5 microns, ovate with small apiculus projecting in face view, strongly limoniform [lemon-shaped] with distinct small apiculus and low to moderate beak in side view, verruculose to verrucose, pale to medium pale amber in KOH, pale straw in water; basidia (2-)4-spored, 26-36 x 6-7.5 microns, clavate, colorless (brownish in older specimens); cheilocystidia abundant and crowded, emanating from the gill trama to form a dense gelatinous layer, variable in length (15-45 microns long), narrowly to broadly clavate, apex usually 5-7 microns wide above a long 3-4 microns wide pedicel, these elements often intermixed with narrower (2-3 microns), cylindric and / or wider (up to 10 microns) clavate elements, cheilocystidia thin-walled, colorless or when old filled with oil brownish contents; hyphidia (paracystidia) occasional within basidial clusters, 2 microns wide, filiform; pileipellis [cap cuticle] a 2-layered ixocutis, the suprapellis 150-350 microns thick, colorless, hyphae long, 1-3 microns wide, branched, straight or occasionally curling, colorless, and "gelatinized with the uppermost hyphae uplifted from a radially aligned base within a gelatinous matrix", the subpellis brilliant amber-orange, hyphae 3-5 microns wide at septa but inflated to 5-10 microns, thin-walled, "with intraparietal pigments most noticeable at the septa"; all tramal tissues gelatinized, colorless; tibiiform diverticula abundant on remnants of pellicular sheath on pseudorhiza and stipitipellis; clamp connections absent in all tissues

Spore deposit:
cinnamon-brown

Notes:
Phaeocollybia rifflipes is known from about 10 sites in BC, WA, OR, and CA, (Norvell(11)).

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