Lignomyces vetlinianus (Domański) R.H. Petersen & Zmitr., in Petersen et al., Mycologia 107(5): 1046 (2015)
Basidiomata pleurotoid-pseudostipitate, not effuse-reflexed, aris-ing deep within woody substratum root-like base, reniform, orbiculate, auriform, dimidiate to broadly cuneiform with inrolled margin. Pileus 25–70(–100) x 30–80(–150) mm; pileus surface initially pubes-cent, becoming hispid or furry; superficial “spikes” 1–2 mm high at maturity, initially off-white, mellowing to cream colored, perhaps near “light ochraceous buff” (5A4), sometimes with isabel-line tint; margin thin, initially inrolled, moderately undulate, ivory white. Pileus trama white, when dried revealing delicately marbled texture; gelatinized layer juxtaposed to lamellae, 1–2 mm thick, hardly detectable when fresh but when dried becoming glassy and dark ochraceous. Lamellae 1–7(–10) mm broad, thin (i.e. bladelike), off-white, entire (not serrate but serrulate at the base in old basidiomata), easily cracked, gradually narrow-ing downward on stipe, convergent on upper stipe, when dried becoming somewhat cartilaginous and exhibiting a glassy (gelatinized) trama (50 x); partial veil absent; lamellulae in 2–3 ranks. Stipe portion tough-fleshy becoming hard-spongy, narrowing from the broadly cuneiform pileus, 3–25 mm thick, initially soaked, becoming dry and hard; stipe flesh white when fresh, macroscopi-cally homogeneous, bruising ivory with weak rose or isabelline tints; stipe base slightly enlarged, but insertion in woody substrate apparently narrowed. Odor strong, slightly rancid; flavor reminiscent of Postia tephroleuca.
Basidiospores (5.2–) 7.5–8.7 3 (2.8–)3.5–4.5(–5) μm (M = 7.3 x 3.9 μm; Q = 1.67–2.14; Qm = 1.89; Lm = 7.35 μm), plump-ellipsoid, occasionally with a suggestion of concavity (slightly reniform), thin-walled, hyaline, inamyloid, non-dextrinoid; contents with several scattered, re-fringent guttules (PhC); wall weakly cyanophilous.Basidia 25–34 x 6–8 μm, clavate, arising from a clamp connection, four-sterigmate (sterigmata –5 mm long); contents multiguttulate; guttules refringent, scattered, usually large at basidial base and apex. Pleurocystidia infrequent to common, (20–) 39–65 x (3.8–) 6–9 μm, usually narrowly fusiform, but also hyphoid, ventricose or obscurely tibiiform, thin-walled, hyaline, arising from subhymenium, extending beyond hymenium 10–35 μm; contents subrefringent, homogeneous. Lamella edge fertile with scattered cheilocystidia; cheilocystidia (22–)49–66(–80) x (3.8–)5–8 μm, protruding beyond hymenium 10–20 μm, narrowly fusiform to cylindrical, easily disarticulated from source (no clamp seen), hyaline; contents subrefrin-gent, homogeneous. Pileipellis composed of radially arranged hyphae similar to those of stipe trama, with slender hyphal type dominant, firm-walled, frequently clamped; hyphae of cutis repent but with frequent erect hyphal termini ranging from straight, firm-walled, to somewhat gnarled and often branched. Hyphae of superficial pileipellis –5 μm diam nearorigin, gradually tapering throughout length to < 1 μm diam, apparently firm-walled (wall thickness not measur-able, refringence dictated by orientation to light source [PhC]; not uniformly refringent due to wall thickness), rarely forked; clamp connections occa-sional, conspicuous. Pileus tramal hyphae 2.5–10.5 μm diam, tightly interwoven, moderately thick-walled (wall –0.5 mm thick; generative) to gelatinized (appearing pseudoskeletal, often obscuring cell lu-men; gelatinized wall irregular in depth, –1 μm thick, hyaline), inamyloid, acyanophilous, conspicuously clamped; pseudoclamps and irregular ampulliform swellings present. Also present are utriform swellings (–45 μm diam) stalked, thin-walled, easily semicol-lapsed; contents heterogeneous with many small, scattered granules and one to several larger, refrin-gent, crystalline inclusions. Hyphae of gelatinous layer 6–17 μm diam., parallel, coherent, generally radially oriented, with gelatinized wall (appearing thick-walled but without wall delineation; gelatinization –3 μm thick, hyaline, obscuring cell lumen or lumen capillary [a single fine line]); clamp connec-tions not observed on gelatinized hyphae. Lamellar trama generally radially oriented, gelatinized, quickly swelling in KOH, interwoven; hyphae 1.7–3.2(–7) μm diam., thin- to firm-walled, conspicuously clamped. Subhymenium tightly interwoven, hardly gelatinized; hyphae 2–2.5 μm diam., frequently branched, thin-walled, frequently clamped, producing basidioles and basidia as bouquets; contents homogeneous to in-cluding scattered small guttules. Longitudinal scalp of stipe trama: hyphal construction pseudodimitic, of two hyphal types: (i) flagelli-form, slender (1.5–4 μm diam.), firm- to thick-walled (wall –0.5 μm thick), hyaline, arising from a clamped septum, occasionally dichotomously branched with a clamp connection on both branches, conspicuously clamped, with terminus not observed (i.e. whether tapered apically or reverting to a wider hypha at a clamp connection), apparently locally common but not forming a discrete tissue; and (ii) stouter (5–8 μm diam.), thick-walled (wall –0.7 μm thick), hyaline, meandering or gnarled, occasionally septate and then clamped, tightly interwoven.
Habitat: On standing or fallen dead beech (Fagus sylvatica) or aspen (Populus tremula) in mixed conifer-deciduous forest. Russian locations all apparently near swamp.
Index Fungorum number: IF811173