Marasmius nigrobrunneus (Pat.) Sacc.
Pileus 3–28 mm diam, hemispherical to convex when young, becoming plano-convex and shallowly umbilicate in age, with or without small black papilla in the umbilicus, striate to plicate; surface dull, dry, glabrous to pruinose; disc dark grey to black, margin greyish brown (6F3) to brownish grey (9F2).Contextthin, greyish white to cream. Lamellae adnate to a collarium, subdistant (9–17) with no lamellulae, non-intervenose, broad (2–4 mm), yellowish white when young, becoming pale-yellow in age, with brown to dark brown edges. Stipe 52– 214 × 0.3–0.5 mm, central, cylindrical, wiry, shiny, solid, rarely with a few nodes, glabrous, insititious, apex olive brown grading to dark brown at the base when young, dark brown overall in age; arising directly from black rhizomorphs. Odour and taste not distinctive.
Basidiospores (6–)8–10(–13) × (3–)4–5(–7) mm [xmr = 7.4–10.6 × 4.1–6.3 mm, xmm = 9.0 ± 0.9 × 4.7 ± 0.6 mm, Q = 1.4–2.9, Qmr = 1.7–2.2, Qmm = 1.9 ± 0.1, n = 25 spores per 11 specimens], ellipsoid, smooth, hyaline, inamyloid, thinwalled. Basidia 25–27 × 5.0–7.5 mm, clavate to cylindrical, 4-spored. Basidioles fusoid to cylindrical. Cheilocystidia common, of Siccus-type broom cells; main body (11-)14–20(–30) × (4–)7–14(–19) mm, cylindrical to clavate, pyriform or sometimes irregular in outline, hyaline, thin- to thick-walled; apical setulae (2–)3–9(–15) × 1–2(–2.5) mm, crowded, cylindrical or irregular in outline, obtuse to subacute, dark grey to black, inamyloid, thick-walled. Pleurocystidia absent. Pileipellis hymeniform, mottled to weakly mottled, composed of three types of cells: (1) Siccus-type broom cells (Fig 4G), main body (11–)15–27 × (7–)10–15(–18) mm, clavate to broadly clavate, pyriform or sometimes irregular in outline, yellowish brown, inamyloid, thin- to thick-walled; apical setulae 2–9 × 1–2(–2.5) mm, cylindrical to conical or irregular in outline, obtuse to subacute, dark grey to black, inamyloid, thin- to thick-walled; (2) Globulares-type cells (Fig 2E), 14–28 × 11–12 mm, subglobose to clavate, sometimes irregular in outline, dark grey to black, inamyloid, thin-walled; (3) cells transitional between broom cells and non-setulose cells (Fig 2F), main body 20–22 15–17 mm, broadly clavate to pyriform with a few knob- like apical setulae 6–13 4–8 mm, dark grey to black, thin- to thickwalled. Pileus trama interwoven; lamellar trama regular; hyphae 3–7 mm diam, cylindrical to inflated, smooth, hyaline, inamyloid, thin-walled, non-gelatinous. Stipe tissue monomitic; cortical hyphae 4–8 mm diam, parallel, cylindrical, smooth, dark brown, dextrinoid, thick-walled (1–2 mm), non-gelatinous; medullary hyphae 3–8 mm diam, parallel, cylindrical, smooth, hyaline, inamyloid, thick-walled (1–2 mm). Caulocystidia absent. Clamp connections present.
Habitat: Scattered to gregarious on bamboo leaves and stems, or rarely on undetermined dicotyledonous leaves. Africa, Caribbean region, South America, India, Sri Lanka, Papua New Guinea, Vietnam, Thailand.
Material examined: Thailand: Chiang Mai Province: Doi Suthep-Pui National Park, Sangra Sabhasri Land to Huai Kok Ma Village, N18◦48.402’ , E98◦54.617’ , alt. 1146 m, 30 Jun. 2003, N. Wannathes 010 (CMU, SFSU); Doi Suthep-Pui National Park, Mok Fa waterfall, N19◦6.581’ , E98◦46.353’ , alt. 1014 m, 13 Aug. 2003, N. Wannathes 101 (CMU, SFSU); same location, 25 Jun. 2005, N. Wannathes 339 (CMU, SFSU); same location, 29 Jun. 2004, Y. S. Tan 275 (CMU, SFSU); Mae Taeng District, Phadeng Village, Pathummikaram temple, N19◦06’ 28.80”, E98◦44’ 47.30”, alt. 1050 m, 25 Aug. 2003, N. Wannathes 129 (CMU, SFSU); Mae Taeng District, Tung Joaw Village, N19◦8.07’ , E98◦38.90’ , alt. 1423 m, 20 Jun. 2004, N. Wannathes 162 (CMU, SFSU); Mae Taeng District, Mae Sae Village, Pang Sa Ded Water Conservation Area, N19◦14.60’ , E98◦38. 46’, alt. 962 m, 26 Jun. 2005, N. Wannathes 347 (CMU, SFSU). Phrae Province: Maung District, Cherng Thong waterfall, 16 Aug. 2005, N. Wannathes 416 (CMU, SFSU); same location, 19 Aug. 2005, N. Wannathes 435 (CMU, SFSU). Chiang Rai Province: Maung District, Khun Con waterfall, N19◦50’ 38.60” E99◦39’ 7.40”, alt. 577 m, 12 Jun 2005, N. Wannathes 302 and 311 (CMU, SFSU).
Notes: Our specimens of Marasmius nigrobrunneus from northern Thailand match quite closely those reported by Singer (1958, 1976) and Pegler (1983, 1986) from Sri Lanka, India, Sierra Leone, Trinidad, Bolivia and Argentina, including forming lamellae with greyish brown edges and stipes that often arise from black rhizomorphs. They differ only slightly from specimens reported from Vietnam (type; Patouillard 1891) and Papua New Guinea (Desjardin & Horak 1997) that lack a coloured lamellar edge, and were not reported to arise from black rhizomorphs. The species is commonly found on bamboo debris and the combination of dark grey to greyish brown pileus, distant collariate lamellae with or without coloured edge, long, black, wiry stipes often associated with rhizomorphs, and versiform pileipellis broom cells are distinctive features for the species. A recent type study was published by Yang (2000: p. 437).
Fig. 1 Colour photos of Thai Marasmius. (A) Marasmius apatelius (N. Wannathes 265). (B) Marasmius nigrobrunneus (N. Wannathes 435). (C) Marasmius cremeus (N. Wannathes 154). Bars =10 mm.
Fig. 2 Marasmius nigrobrunneus (N. Wannathes 129). (A)Basidiomes. (B) Basidioles. (C) Basidiospores. (D) Cheilocystidia. (E) Globulares-type pileipellis cells. (F) Pileipellis cells
transitional between broom cells and non-setulose cells. (G) Siccus-type pileipellis cells. Bar: (A) 20 mm; (B–E) 10 mm.
Wannathes N, Desjardin DE, Lumyong S 2007– Mating studies, new species, and new reports of Marasmius from northern Thailand. Mycological Research 111: 985-996. https://doi.org/10.1016/j.mycres.2007.06.013