Thelephora asperula (P. Karst.) Kõljalg, I. Saar & Svantesson 2024

Syn.: Tomentella asperula (P. Karst.) Hoehn. & Litsch. 1906

Basidiome effused, loosely adherent to separable or, in part, completely detached from substratum, up to 0.5 (1) mm thick.
Hymenophore smooth to strongly colliculose, compact, becoming somewhat crustose when old. Colliculi spaced to crowded and concrescent, 1–4 (7) per mm, 0.1–0.2 mm across, easy peeled off from the subiculum.
Hymenial surface continuous, when fresh brownish, grey brown, green brown to (very) dark green-grey brown, fading on drying to light brown, light grey brown, light olive brown, brownish or olivaceous brown, evidently darker than the subiculum.
Subhymenium thickening, tomentose or felted, englobing numerous spores and (by this) more or less concolour with the hymenial surface.
Subiculum and context hypochnoid to tomentose or fibrous, poorly developed to thick, whitish or very pale yellowish-brown, usually with numerous rhizomorphs.
Margin fertile throughout and indistinct to sterile and wide, thinning out and araneose to byssoid or fimbriate, whitish to light yellowish, normally turning yellowish or light grey when dry.
Rhizomorphs infrequent to common in subiculum, finally building up a conspicuous part of the subicular layer; sometimes easily seen at the margin and in cracks of the substratum, up to 0.1 (0.2) mm in diam., sometimes fasciculate and up to 0.5 mm wide, irregularly intertwined and richly branched to fan-shaped, soft, cottony, flexible, not fragile; surface pubescent, with numerous projecting hyphae; normally white, sometimes light grey, very pale brown, pale yellowish brown.

Hyphal system monomitic or dimitic with skeletal hyphae associated with rhizomorphs.
Subicular hyphae of one or two kinds: 1) generative fibulate, regular, (2) 2.5–6 (7) µm, with thin or thickening wall or even solid wall (up to 2.5 µm) with lumen often difficult to observe, rarely with localized thickenings, hyaline to subhyaline or slightly yellowish, sometimes with short, simple anastomoses, horizontally oriented, at the base of colliculi more loose and irregularly oriented; 2) some rare skeletal hyphae, always associated with rhizomorphs.
Subhymenial hyphae almost regular, fibulate, (2) 2.5–4 (5) µm, short-celled, frequently branched from clamps, thin-walled, hyaline or subhyaline, loose and vertically arranged when hymenial surface is smooth, compact, often collapsed and with radiating orientation inside colliculi.
Rhizomorphs simple to differentiated.
— When poorly developed built up by 1) some generative hyphae regular, fibulate or with some infrequent simple septa, (2) 2.5–4 (5) µm wide, branching at some distance from septa, sometimes with simple, short anastomosis, with thin to slightly thickening walls, infrequently with thick walls, hyaline, interwoven with 2) some generative hyphae, regular, straight, fibulate or with some secondary simple septa, up to 7 µm wide, cells of variable length, up to 300 (500) µm, with solid walls (2.5 µm) and a narrow lumen, sometimes with localized thickenings, hyaline to subhyaline.
— Soon with few skeletal hyphae, regular, straight, rarely with some elbow-like bends, 1.5–2 (2.5) µm, with solid walls and narrow lumen, hyaline, starting from generative hyphae, characteristically with a thin skeletal hypha 0.8–1.5 µm thick, branching at right angle at 5–10 µm from the last clamp (see notes).
— When well developed with 1) a central core of broad hyphae, often sausage-shaped, simple-septate or with small sclerified clamps difficult to see, 8-16 µm in diam., mostly with thin or slightly thickening walls, hyaline or sometimes subhyaline, 2) a mediostratum built up by normal generative hyphae as described above, 3) an outer layer built up mostly by skeletal hyphae that may become the dominant kind of hyphae of the older rhizomorphs.
Cystidia absent.
Basidia narrowly clavate to subcylindrical, sinuous, 40–70 (80) x 8–10 (12) (apex), 6–8 (lower middle), 4–5 µm (base), hyaline or very pale yellowish, fibulate at the basal septum; 4 sterigmata up to 7 (9) µm long and 1.5–3 µm wide at the base.
Basidiospores globose to subglobose, sometimes broadly ellipsoid, with regular outline or rarely with slightly sinuos outline [potatiform], 8.5–11 µm across or (8.5) 9–11 (11.5) x (7.5) 8–9 (9.5) x (8) 8.5–9.5 (10) µm, Q¹ = (1.05) 1.1–1.25 (1.3), Q² = (1) 1.05–1.15 (1.2), echinulate, with thickening or thick wall (0.5–1.2 µm), pale yellowish brown, yellowish-brown, olivaceous, brownish, greyish-brown, darker than all other elements. Aculei varying between collections: in some small and slightly crowded, up to 0.5 (1) x 0.2–0.5 µm, in other longer, stronger and fewer, up to 1.5 (2.5) x 0.5–1 (1.2) µm.
Chlamydospores absent.
Incrustation: almost all hyphae and hymenial elements coarsely to strongly encrusted by weakly adhering granular hyaline crystals visible in water mounts, almost completely dissolving in KOH and other dyes.

description: Elia Martini

drawing: H. Maser photo: Elia Martini