First person to use this name on MO: Image Sharer
On rotting wood/bark of fagalean trees (Castanopsis-Lithocarpus), in tropical-montane rain forest, 1100 m a.s.l.
Distribution: Papua New Guinea.
Horak, E. 2006. Three new species of Psilocybe (Strophariaceae, Basidiomycota) from Papua New Guinea. Sydowia. 58(1):3-14
Pileus 10-25 mm, in young and old specimens with distinctive, conical to sharply pointed papilla, strongly translucent-striate margin incurved, yellow-brown to date brown if moist, strongly hygrophanous, pale ochre-brown upon drying, dry, smooth, veil remnants absent. Lamellae 28-36 reaching stipe, lamellulae in 3-7 series, densely crowded, broadly adnate, often subdecurrent with short tooth, up to 2.5 mm wide, at first argillaceous brown gradually turning beige-brown, fimbriate edges whitish. Stipe 20 -45 × 1.5-3 mm, cylindrical, equal or gradually becoming broader towards base, upper portion concolorous with lamellae, fuscous or black-brown in lower portion, fibrillose cortina fugaceous, but with distinctive persistent white appressed fibrils towards base, with short concolorous rhizoids, dry, hollow, tough, solitary or fasciculate. Context pale yellow-brown in pileus, fuscous in stipe, unchanging.
Odor and taste not distinctive.
Chemical reactions on pileus: KOH – negative.
Spore print brown (lilac tints absent). – Basidiospores 4.5 – 5 (- 5.5) x 3 – 3.5 um, ovoid in face view, weakly amygdaliform in side view, brown (in KOH), thin-walled, smooth, germ pore small but distinctive. Basidia 15-20 × 3-4.5 um, 4-spored, sterigma up to 3 um long, clamped. Cheilocystidia polymorphic, shape ranging from clavate or fusoid (20 – 35 × 8 – 11 am) to distinctly fusoid with elongate neck (30 – 4 5 × 4 – 9 urn), hyaline, thin-walled, occasionally covered with resinous or gelatinous incrustation, plasmatic pigment absent. – Pleurocystidia 25 – 45 × 12 – 18 (-20) urn, broadly and obtusely fusoid or utriform, hyaline, thin-walled. – Caulocystidia 2 0 – 4 0 × 4 – 6 urn, scattered, polymorphic, mostly cylindrical to slender fusoid, with short mucronate or finger-like projections, hyaline. – Pileipellis a cutis composed of repent, cylindrical hyphae, 2 – 4 ( – 5 ) u m diam., terminal cells differentiated, slender fusoid, rarely with irregular finger-like projections, non-gelatinized walls hyaline, thin, encrusted with brown pigment. Subpellis composed of regular cylindrical hyphae, 5-15 urn diam. Oleiferous hyphae absent. -Clamp connections present.
Etymology: fibrillosus (Lat.) – fibrillose; pes (Lat.) – foot.
Specimen examinded: PAPUA NKWGUINEA: Morobe District, Bulolo, Watut,
10 May 1973, leg. Horak73-207 (Holotypus, ZT).
Habitat and Ecology: Saprobic. – On rotting wood/bark of fagalean trees (Castanopsis-Lithocarpus), in tropical-montane rain forest, 1100 m a.s.l.
Distribution: Papua New Guinea.
Discussion: According to the keys published by Guzman (1983, 1995) Psilocybe fibrillosipes can readily be accomodated in sect. Singerianae. Macroscopically this Papuan species is recognized by its conical pileus and the conspicuous white fibrillose veil remnants covering the lower portion of the fuscous stipe. The most distinctive features of Ps. fibrillosipes are, however, the polymorphic cheilo- cystidia, the broadly fusoid or utriform pleurocystidia and the remarkably small, ovoid basidiospores measuring only 4.5 – 5 (-5.5) x 3-3.5 fim.
The macroscopical characters of Psilocybe fibrillosipes are recalling the closely related Ps. washingtonensis A.H. Sm. (Smith & Hesler 1946), reported from the Pacific North West, USA. This taxon, however, is clearly separated from the Papuan species by the shape and size both of the pleurocystidia and the basidiospores.