Musumecia bettlachensis Vizzini & Contu, in Vizzini et al., Nordic Journal of Botany 29(6): 735 (2011)
Etymology: The specific epithet refers to Bettlach, the French locality where the type collection was made.
Pileus 2–8 cm broad, subglobose-hemispheric at first, with the disc slightly umbonate, then expanding to plane, finally shallowly depressed; margin broadly decurved and inrolled at first, then horizontal, finally broadly undulate, not pellucid-striate, sometimes minutely ribbed. Surface dry, not hygrophanous, at first sericeous, finely tomentose-fibrillose streaked with fine fibrils, then glabrous and smooth in age; colour pure white (4A1), ivory-white (4 B2 C2) or cream-white (5A3), with darker sordid cream-brown (5C3) spots when moist or in age. Lamellae [L=(20) 25–32; l=1–2(3)] interspersed with lamellulae, broadly adnate at first, becoming decurrent to long decurrent, distant, thick, 2–6 mm broad, rarely anastomosed, at times intervenose or forked towards the stipe; at first pale salmon-pink (8A2), then becoming ochre-yellow (3A3-4) and finally greyish-brown (4D4), with an even concolorous edge. Stipe 2–8 x 0.5–1.0 cm, cylindrical or somewhat broadened towards the apex, slightly bulbous at the base, usually flexuous, subcartilagineous to fleshy, solid then fistulose, caespitose, arising from a white pseudosclerotioid flattened mass incorporating plant debris and particles of soil; surface finely pruinose-floccose, at first concolorous with the pileus, then brownish (4D4, 4E5). Rhizomorphs present, conspicuous, white. Context quite firm, fibrous in the stipe, whitish cream with alutaceous hues (3A3-4), 4-7(10) mm thick at pileus disc. Smell faint but unpleasant, taste mild. Spore-print (on pileus): whitish-cream (4A3).
Basidiospores: (5) 5.5–8.5 x 3.5–5.0 µm, on average 7.0 x 4.2 µm, Q=1.4–1.8, Qm=1.65, hyaline, smooth, wall thin or somewhat thickened, mono-biguttulate, inamyloid, nondextrinoid, acyanophilous, ellipsoid to subamygdaliform, rarely cylindrical in face view, pyriform to lacrymoid in profile, not in tetrads (Fig. 3a). Basidia 32–45 x 5–8 µm, clavate to narrowly clavate, not siderophilous, usually 4-spored, rarely 2-spored. Subhymenium filamentous. Hymenophoral trama regular to subregular, hymenopodial layer consists of 3–12 µm wide hyphae, central trama made up of 8–30 µm wide hyphae, slightly thick-walled, long cylindrical to subphysaloid, rarely allantoid, hyaline, not encrusted. Cheilocystidia and pleurocystidia absent. Pileipellis a slightly gelified cutis; hyphae 4–17 µm wide, cylindrical or sinuate, smooth, hyaline or pale yellow in KOH, with scattered erect and repent terminal elements, cylindrical to fusiform-lageniform, 30–60 x 3.5–8.0 µm; pigment parietal when present, faintly yellow in KOH. Pileitrama hyphae 6–32 µm in diameter, cylindrical, broadly cylindrical, subphysaloid or inflated, smooth, walls usually slightly thickened, refractive, hyaline to faintly yellow in KOH, with rare pseudoclamps. Stipitipellis slightly gelified, hyphae 4–18 µm wide, slightly pigmented, not encrusted, thick-walled (wall up to 0.8 µm thick), with scattered, caulocystidia-like, clavate to pyriform or forked at apex, erect and repent terminal cells. Stipititrama hyphae 5–30 µm wide, cylindrical-subphysaloid, swollen at times, rarely suballantoid and thick-walled (wall up to 0.8 µm thick). Thromboplerous hyphae (= oleiferous hyphae sensu Clémençon 2004) rare. Clamp connections absent in whole basidiome. Pseudosclerotial mass of hyaline, thin-walled and clampless, 3–12 µm wide hyphae intermixed with rare thromboplerous hyphae.
Habitat and distribution: Densely gregarious and caespitose, emerging from a conglobate fleshy pseudosclerotial mass in a mixed wood with Abies alba and Fraxinus excelsior, on argillose to stonysandy soil, collected under Abies alba together with Lyophyllum boudieri, Mycena rosea, Pterula subulata, Macrocystidia cucumis, Stropharia cyanea, Galerina stylifera and Lactarius salmonicolor. Autumn. The species is so far known only from the type locality.
Index Fungorum number: IF561610
Figure 1. Musumecia bettlachensis. Basidiomes (from the holotype). (a) young clustered basidiomes with pink lamellae and evident pseudosclerotial basal mass, (b) basidiomes with pink–yellow lamellae. Scale bars=2 cm.