Marasmius apatelius Singer
Marasmius apatelius Singer
Index Fungorum number: IF 333658; MycoBank number: MB 333658.
Pileus 2–7 mm diam, at first hemispherical, becoming convex in age, umbilicate, with or without a brown papilla in the umbilicus; margin striate; surface dull, dry, glabrous, brown (E76–7) in centre, brownish yellow at margin. Context thin, cream (3A2). Lamellae adnate to a free collarium, subdistant (9–16 reaching stipe) with no lamellulae, non-intervenose, narrow, cream (3A2), non-marginate. Stipe 7–33 × 0.1–0.3 mm, central to slightly eccentric, cylindrical, tough, terete, glabrous, insititious, yellowish white at apex when young, becoming reddish brown (8E7) to black overall in age; rhizomorphs absent. Odour and taste not distinctive.
Basidiospores (6–)7–9(–10.5) × (3–)4–5(–5.5) mm [xmr= 7.7–9.2 × 3.9–4.6 mm, xmm = 8.2 0.7 × 4.2 0.3 mm, Q= 1.4–2.6, Qmr= 1.7–2.3, Qmm= 2.0 × 0.3, n= 25 spores per 5 specimens], ellipsoid, curved in profile, smooth, hyaline, inamyloid, thin-walled. Basidia 16–24 × 7–9 mm, clavate, 4-spored. Basidioles clavate to fusoid. Cheilocystidia common, of Rotalis-type broom cells (Fig 1D); main body (16–)23–32(–34) (7–)12–20 mm, clavate to broadly clavate or pyriform, hyaline, thin-walled; divergent setulae 0.5–4 × 0.8–1.5 mm, conical to narrowly cylindrical obtuse, pale yellow to light brown, inamyloid, thick-walled.
Pleurocystidia absent. Pileipellis hymeniform, mottled, composed of Rotalis-type broom cells; main body 16–35 × 10–20 mm, clavate to broadly clavate, pyriform or turbinate, hyaline, inamyloid, thin- to thick-walled; divergent setulae 1–3 × 0.5–1 mm, cylindrical to conical, obtuse, crowded over upper half of cell, yellow to light brown, inamyloid, thick-walled. Pileus trama interwoven; lamellar trama regular; hyphae 3–6 (–13) mm diam, cylindrical to inflated, smooth, hyaline, inamyloid, thin-walled, non-gelatinous. Stipe tissue monomitic; cortical hyphae (2.5–)4–6 mm diam, parallel, cylindrical, smooth, reddish brown to brown, weakly dextrinoid to inamyloid, thin- to thick-walled (up to 1 mm), non-gelatinous; medullary hyphae (2–)3–7(–10) mm diam, parallel, cylindrical, smooth, hyaline, inamyloid, thin-walled. Caulocystidia absent. Clamp connections present.
Habitat: Scattered to gregarious on undetermined dicotyledonous leaves or bamboo debris. Africa, Thailand.
Material examined: Thailand: Chiang Mai Province: Doi Suthep-Pui National Park, Mok Fa waterfall on Hwy 1095, N19º6.581’, E 98º 46.353’, alt. 1014 m, 3 Jul. 2003, N. Wannathes 017 (CMU, SFSU); same location, 21 Aug. 2004, N. Wannathes 265 (CMU, SFSU); Mushroom Research Centre, 27 km marker on Hwy 1095, 27 Jul. 2003, N. Wannathes 035 (CMU, SFSU); same location, 27 Jul. 2003, N. Wannathes 043 (CMU, SFSU); Chiang Mai University, 11 Aug. 2004, N. Wannathes 251 (CMU, SFSU).
Notes. The specimens from northern Thailand match quite closely the descriptions of populations from Africa (Singer 1965; Pegler 1977), except for forming a few more lamellae per basidiome (9–16 versus 9–12). Distinctive features of this species include an entirely brown, umbilicate pileus with or without a brown papilla, collariate and subdistant lamellae, an absence of well-developed rhizomorphs, and small basidiospores with mean 8 × 4 mm. The Rotalis-type broom cells on the pileipellis and lamellae edges indicate placement in sect. Marasmius subsect. Marasmius. This is the first report of this species outside Africa.
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 Microcharacters of A. brunneopileatus Callac & R.L. Zhao, sp. nov. (ZRL2012115) a. basidiospores, b. basidia, c. cheilocystidia, d. pileipellis, bars: a, b = 5 μm, c, d = 10 μm
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
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