Biodiversity and phylogeny of Marasmius (Agaricales, Basidiomycota) from Madagascar Author Shay, Jackie E. Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, CA 94132, USA Author Desjardin, Dennis E. Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, CA 94132, USA Author Perry, Brian A. Author Grace, Chris L. Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, CA 94132, USA Author Newman, Danny S. Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, CA 94132, USA text Phytotaxa 2017 2017-01-25 292 2 101 149 http://dx.doi.org/10.11646/phytotaxa.292.2.1 journal article 10.11646/phytotaxa.292.2.1 1179-3163 13697833 27. Marasmius megistus Singer, Bull. Jard. Bot. État Brux. 34: 356. 1964. ( Fig. 18 , Plate 7 ) Type :— DR CONGO . Binga, 7 May 1928 , M . Goossens–Fontana 733 ( BR 11492–46). Description:— Pileus 6.5–15 mm diam, campanulate; margin deeply sulcate; surface dry, glabrous; disc yellowish grey (4 B 2), sulcae pale violet brown (10 E 4) to reddish grey (10 B 2), ridges and margin buff (4 A 2) to cream (4 A 3). Context thin. Lamellae subfree, distant (14) broad ( 1–2 mm wide), buff (4 A 2), non-marginate. Stipe 104–115 × 1–2 mm , central, cylindrical, hollow; surface glabrous; brownish grey (10D2) to brownish red (10 E 6). Odor and taste not distinctive. FIGURE 18. Marasmius megistus ( JES 163, Lockwood 2132155 ) a) basidiospores; b) basidioles; c) cheilocystidia; d) pileipellis cells. Scale bar = 10 μm. Illustrated by J.E. Shay. Basidiospores (26.4–) 29.6–32.8 (–40) × 4.8–7.2 μm [x mr = 30.7–34.2 × 5.8–6.7 μm; x mm = 32.44 ± 2.49 × 6.23 ± 0.66 μm; Q = 2.8–6.8; Q mr = 5.09–5.33; Q mm = 5.21 ± 0.17, n = 2–27, s =2], narrowly ellipsoid to clavate, smooth, hyaline, inamyloid, thin-walled. Basidia not observed. Basidioles 18.4–57 × 5.6–10.4 μm, clavate to fusoid, hyaline, inamyloid, thin-walled. Cheilocystidia evenly distributed, of Siccus - type broom cells; main body 16–25.6 × 4.8–9.6 μm, clavate or irregular, 2–3-lobed, hyaline, inamyloid, thin-walled; apical setulae 0.8–8 × 0.8–1.6 μm, cylindrical to conical, sometimes branched, hyaline, inamyloid, thin-walled. Pleurocystidia absent. Pileipellis not mottled, a hymeniform layer of Siccus - type broom cells; main body 16–32 × 6.4–10.4 μm, clavate or irregular, hyaline, inamyloid, thin-walled; apical setulae 2.4–8 × 0.8–3.2 μm, few per cell, broadly conical to cylindrical or utriform, seldom branched, hyaline, inamyloid, thin-walled. Pileus trama interwoven; hyphae 1.6–8 μm diam, cylindrical smooth, hyaline, dextrinoid, thick-walled. Lamellar trama regular; hyphae 2–7.2 μm diam, cylindrical to inflated, smooth, hyaline to pale yellow, dextrinoid, thin-walled. Stipe tissue monomitic; cortical hyphae 1.6–8 μm diam, parallel, cylindrical, smooth, pale yellow, green brown, dextrinoid, thick-walled; medullary hyphae 1.6–9.6 μm diam, parallel, cylindrical to inflated, smooth, hyaline, dextrinoid, thin-walled. Caulocystidia absent. Clamp connections present. Habit, habitat and known distribution:—Solitary on dicotyledonous leaves. Africa ( Burundi , Cameroon , DR Congo, Tanzania , 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 163 ( TAN ) ; Region Vatovavy-Fitovinany , District Ifanadiana , Commune Ranomafana , February 2013 , T . Lockwood 2132155 ( SFSU ) . Notes:— Marasmius megistus forms some of the largest basidiospores in the genus. The Madagascan material is distinguished by a relatively small (up to 15 mm diam) sulcate striped pileus with violet-brown sulcae and cream ridges, distant non-marginate lamellae, a very long (up to 115 mm ) glabrous stipe, basidiospores in the range 29.6–40 × 4.8–7.2 μm, no pleurocystidia, Siccus - type broom cells with few setulae, and growth singly on dicotyledonous leaves. Antonín (2007) reports the species as forming a larger pileus ( 26–50 mm diam) but in all other respects the specimens from Madagascar match those reported from tropical Africa. ITS sequences of two Madagascan specimens ( KX148992 , KX148993 ) are sister to a specimen from São Tomé ( KX953750 ) with strong support (100% BS, 1.0 PP; Fig. 1a ) .