Type:— DR CONGO. Near Yambao, 21 June 1939, J. Louis 15275 (BR 11426–77).

Description:— Pileus 12–17 mm diam, convex to plano-convex; disc and margin smooth to rugulose; surface, dry, glabrous; orangish red or orange. Context thin, buff. Lamellae subfree, close, narrow, white to buff (5 A 4–5), non-marginate. Stipe 30–49 × 1 mm, central, cylindrical, hollow; surface pruinose; apex cream to yellow, becoming orange (7 C – E 7–8) to brown (6D7) towards the base. Odor and taste not distinctive.

Basidiospores (6.4–) 8–11.2 × 3.2–4.8 μm [x m = 9.08 ± 1.08 × 4.04 ± 0.33 μm; Q = 1.67–2.80; Q m = 2.26 ± 0.14, n = 25, s = 1], ellipsoid, smooth, hyaline, inamyloid, thin-walled. Basidia 16.8–17.6 × 7.2 μm, clavate, 4- spored, hyaline, inamyloid, thin-walled. Basidioles 8–15.2 × 3.2–6.4 μm, clavate to fusoid, hyaline, inamyloid, thin-walled. Cheilocystidia of two types of cells: 1) Siccus - type broom cells with main body 8–17.6 × 6–12 μm, clavate to cylindrical or irregular, hyaline, inamyloid, apically thick-walled; apical setulae 0.8–10.4 × 0.8–1.6 μm, cylindrical to conical, hyaline to golden brown, inamyloid, thick-walled; 2) interspersed non-setulose cells, clavate, smooth, hyaline, inamyloid, thin-walled. Pleurocystidia absent. Pileipellis mottled, a hymeniform layer of Siccus - type broom cells; main body 8–20.8 × 3.2–9.6 μm, clavate to broadly clavate, cylindrical or irregular, seldom 2–3-lobed, smooth, hyaline to brown, inamyloid, apically thick-walled; apical setulae 0.8–12.8 × 0.8–1.6 μm, cylindrical to conical, seldom branched, erect, obtuse, pale brown to hyaline, inamyloid, thick-walled. Pileus trama interwoven; hyphae 1.6–12 μm diam, cylindrical, smooth, hyaline, dextrinoid, thin-walled. Lamellar trama regular; hyphae 3.2–19.2 μm diam, cylindrical to inflated, smooth, pale yellowish brown to hyaline, weakly dextrinoid, thin-walled. Stipe tissue monomitic; cortical hyphae 2.4–12 μm diam, parallel, cylindrical to inflated, smooth, pale yellowish brown to hyaline, dextrinoid, thick-walled; medullary hyphae 2.4–9.6 μm diam, parallel, cylindrical to inflated, smooth, hyaline, dextrinoid, thin-walled. Caulocystidia 11.2–24 × 5.6–7.2 μm, versiform, clavate to lageniform or irregular, seldom lobed, smooth, hyaline, dextrinoid, thin-walled. Clamp connections present.

Habit, habitat and known distribution:—Solitary on leaves of Cryptocarya (Lauraceae). Africa (Cameroon, DR Congo, Ghana, Ivory coast, Uganda), Madagascar.

Material examined:— MADAGASCAR. Region Vatovavy-Fitovinany, District Ifanadiana, Commune Ranomafana, Ranomafana National Park, Piste B, elev. 1004 m, GPS: 21˚ 15.413’ S, 47˚ 25.253’ E, 22 January 2014, J. E. Shay 164 (SFSU); Ranomafana National Park, by the river, January 2013, Lockwood 2132268 W250 (SFSU); Andasibe, moist mountain forest, 12 February 1997, leg. B. Buyck, G. Eyssartier and P.- A. Moreau, Buyck 97.425 (PC).

Notes:— Marasmius corrugatiformis is characterized by a relatively small (12–17 mm), rugulose, reddish orange to orange pileus, close, non-marginate lamellae, a pruinose stipe with cream-yellow apex and brownish orange base, basidiospores with mean 9 × 4 μm, Siccus - type cheilocystidia plus a few smooth, clavate cells interspersed, simple, broadly rounded, cylindrical to clavate caulocystidia, and a lack of Siccus - type broom cells on the stipe. It is similar to M. katangensis Singer, but the latter has only one type of cheilocystidia (Siccus - type), and two types of caulocystidia (broom cells and simple cylindrical cells). Repeated attempts to generate ITS sequences from JES 164 were unsuccessful; however, an ITS sequence of Madagascar material determined as M. corrugatiformis (Buyck 97.425, KX 148981) formed a clade with several sequences of M. corrugatiformis from São Tomé (KX 953756, KX 953757) but with low support (Fig. 1b).