Marasmius sokola J.E. Shay & Desjardin, 2017

Shay, Jackie E., Desjardin, Dennis E., Perry, Brian A., Grace, Chris L. & Newman, Danny S., 2017, Biodiversity and phylogeny of Marasmius (Agaricales, Basidiomycota) from Madagascar, Phytotaxa 292 (2), pp. 101-149 : 135-136

25. Marasmius sokola J.E. Shay & Desjardin , sp. nov. ( Fig. 17 )

MycoBank no.: MB 818621

Holotype:— MADAGASCAR. Commune Ranomafana , District Ifanadiana , Region Vatovavy-Fitovinany, Ranomafana National Park, 22 Jan. 2014, J. E. Shay 154 ( SFSU).

Etymology:— sokola –Malagasy for chocolate, referring the dark chocolate brown colored basidiomes.

Description:— Pileus 20 mm diam, campanulate; disc rugulose; margin sulcate; surface dull, glabrous; dark brown (5E7). Context thin. Lamellae subfree, distant (11), no lamellulae, broad (4 mm), light grey (5C3), with brown edges. Stipe 45 × 1 mm, central, cylindrical, hollow, pliant; surface glabrous; dark greyish brown (6F4). Odor and taste not distinctive.

Basidiospores (16.8–) 18.4–23.2 (–26.4) × 4–4.8 μm [x m = 21.93 ± 2.36 × 4.40 ± 0.40 μm; Q = 3.50–6.40; Q m = 5.03 ± 1.20, n = 25, s =1], subcylindrical to subfusoid, smooth, hyaline, inamyloid, thin-walled. Basidia 32.8– 46.4 × 6.4–8 μm, clavate, 4-spored, hyaline, inamyloid, thin-walled. Basidioles 29.6–42.4 × 7.2–8.8 μm, clavate, hyaline, inamyloid, thin-walled. Cheilocystidia abundant, of Siccus - type broom cells; main body 14.4–22.4 × 6.4–8.8 μm, clavate to subglobose or irregular, seldom 2–3-lobed, hyaline, inamyloid, thin-walled; apical setulae 0.8–13.6 × 0.8–1.6 μm, cylindrical to conical, often branched, brown, inamyloid, thick-walled. Pleurocystidia absent. Pileipellis mottled, a hymeniform layer of Siccus - type broom cells; main body 8.8–22.4 × 5.6–10.4 μm, cylindrical to clavate or irregular, seldom 2–3-lobed, hyaline, inamyloid, thick-walled; apical setulae 0.8–9.6 × 0.8–1.6 μm, cylindrical to conical, seldom branched, hyaline to brown, inamyloid, thick-walled. Pileus trama interwoven; hyphae 2.4–17.6 μm diam, cylindrical to inflated, rough, hyaline, dextrinoid, thick-walled. Lamellar trama regular; hyphae 3.2–8.8 μm diam, cylindrical, smooth, hyaline, dextrinoid, thin-walled. Stipe tissue monomitic; cortical hyphae 3.2–11.2 μm diam, cylindrical, smooth, pale greenish brown, dextrinoid, thick-walled; medullary hyphae 2.4–12.8 μm diam, cylindrical to inflated, smooth, hyaline to pale brown, inamyloid, thin-walled. Caulocystidia absent. Clamp connections present. Habit, habitat and known distribution:—Solitary on woody sticks of Weinmannia ( Cunoniaceae ). 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 154 (SFSU).

Notes:— Marasmius sokola is characterized by a dark brown, smooth to rugulose pileus 20 mm diam, distant (11), broad (4 mm), brown-marginate lamellae, a glabrous, dark brown stipe 45 mm long, basidiospores with mean 21.9 × 4.4 μm (Q = 5.0), basidia 32–46 μm long, Siccus - type cheilocystidia and pileipellis cells with brown setulae up to 12 μm long, no pleurocystidia or caulocystidia, and growth on woody dicotyledonous debris. The new species shows closest phenetic similarity to M. carcharus Singer , M. selangorensis Y.S. Tan & Desjardin , and M. mazatecus Singer. Marasmius carcharus , described from the DR Congo, differs in a pinkish brown pileus, broader (6–7 mm), non-marginate lamellae, cheilocystidia with shorter apical setulae (up to 8 μm), and growth on dicotyledonous leaves ( Antonín 2007). Marasmius selangorensis , described from Malaysia, differs in a paler brown pileus with pink tones, narrower and more numerous (12–18) lamellae, and growth on dead dicotyledonous leaves ( Tan et al. 2009); its micromorphology is indistinguishable from M. sokola . ITS sequences of two specimens of M. selangorensis from Malaysia ( Fig. 1a ), however, show only 70% similarity to JES 154 (KX148994) ( Fig. 1b ) and are distant in the ITS phylogeny. Marasmius mazatecus , described from Mexico, differs in an orange-ferruginous pileus, fewer (9) and narrower (2 mm) lamellae with orange-ferruginous edges, a shorter (20 mm) stipe, and slightly shorter basidiospores (17–21 μm) ( Singer 1976). Marasmius sokola is on a long branch in the ITS phylogeny, sister to M. imitarius Wannathes, Desjardin & Lumyong , a species described from Thailand.

Figures

FIGURE 1a. Maximum likelihood phylogeny based on ITS sequence data. Marasmius from Madagascar are indicated in bold type.Values separated by / refer to nonparametric ML bootstrap proportions and Bayesian posterior probabilities, respectively. Values greater than 70/0.70 are shown (- designates a value below 70% or below 0.70). Nodes receiving support values greater than 90/0.95 are represented by bold branches. G—sect. Globulares; N—sect. Neosessiles; SA—sect. Sicci ser. Atrorubentes; SL—sect. Sicci ser. Leonini; SH—sect. Sicci ser. Haematocephali.

FIGURE 17. Marasmius sokola (JES 154) a) basidiospores; b) basidia; c) basidioles; d) cheilocystidia; e) pileipellis cells. Scale bar = 10 μm. Illustrated by J.E. Shay.