Marasmius somalomoensis Antonín, Mycotaxon (MM)

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 : 112-114

2. Marasmius somalomoensis Antonín, Mycotaxon 88: 66. 2003. ( Fig. 3 , Plate 1 )

Type:— CAMEROON. Sud Province, Somalomo, Dja Biosphere Reserve, 8 April 2001, V. Antonín Cm 01.42 ( BRNM 666108).

Description:— Pileus 2–9 mm diam, plano-convex to campanulate, umbilicate, with a brown papilla; margin plicate to sulcate; surface dry, glabrous; tan to pale brown (4–5 A 3). Context thin (<1 mm), white. Lamellae adnate to a collarium, distant to subdistant (11–14), no lamellulae, broad, buff (4 A 2), non-marginate. Stipe 13–32 × <0.5 mm, central, narrow, wiry, twisted, insititious; surface glabrous; dark brown (6 F 8). Odor and taste not distinctive.

Basidiospores (6.4–) 7.2–10.4 × 3.2–4.8 μm [x mr = 7.9–9.3 × 3.6–3.9 μm; x mm = 8.53 ± 0.70 × 3.79 ± 0.10; Q = 1.5–2.8; Q mr = 2.18–2.44; Q mm = 2.27 ± 0.10, n = 25, s = 3], ellipsoid to narrowly ellipsoid, smooth, hyaline, inamyloid, thin-walled. Basidia 16.8–22.4 × 6.4–7.2 μm, cylindrical to subclavate, 4-spored, hyaline, inamyloid, thin-walled; sterigmata 3.2–4.8 × 0.8 μm. Basidioles 18.4–24 × 5.6–8 μm, clavate to fusoid, hyaline, inamyloid, thin-walled. Cheilocystidia few, of Rotalis - type broom cells; main body 7.2–28.8 × 6.4–21.6 μm, cylindrical to clavate, subglobose or irregular, hyaline, inamyloid, thin-walled; divergent setulae 0.3–1.6 × 0.8 μm, dense, cylindrical, hyaline, inamyloid, thin-walled. Pleurocystidia absent. Pileipellis mottled, a hymeniform layer of Rotalis - type broom cells; main body 12–31.2 × 8.8–24 μm, globose to subglobose, broadly clavate or irregular, hyaline, inamyloid, thin-walled; divergent setulae 0.5–1.6 × 0.5–1.6 μm, dense, cylindrical, hyaline to brown, inamyloid, thin-walled. Pileus trama interwoven; hyphae 1.6–12 μm diam, cylindrical to inflated, smooth, hyaline, inamyloid, thin-walled. Lamellar trama regular; hyphae 1.6–14.4 μm diam, cylindrical to inflated, smooth, inamyloid, thin-walled. Stipe tissue monomitic; cortical hyphae 2–8.8 μm diam, parallel, cylindrical, dark brown, dextrinoid, thick-walled; medullary hyphae 1.6–8 μm diam, parallel, cylindrical to inflated, hyaline, inamyloid, thin-walled. Caulocystidia absent. Clamp connections present.

Habit, habitat and known distribution:—Solitary or in small gregarious clusters on Uapaca densifolia (dicot, Phyllanthaceae ). Africa ( Cameroon, DR Congo), Madagascar.

Material examined:— MADAGASCAR. Commune Ranomafana , District Ifanadiana , Region Vatovavy-Fitovinany , Ranomafana National Park, Talatakely Trail, elev. 973 m, GPS: 21˚ 15.44’ S, 47˚ 25.116’ E, 20 January 2014, J. E. Shay 129 ( SFSU) ; Ranomafana National Park , Piste B, elev. 1004 m, GPS 21˚ 15.413’ S, 47˚ 25.253’ E, 22 January 2014, J. E. Shay 165 ( SFSU) ; District Moramanga , Region Alaotra-Mangoro , Commune Andasibe , Vohimana forest, Piste 5, elev. 844 m, GPS 18˚ 55.422’ S, 48˚ 30.201’ E, 27 January 2014, J. E. Shay 181 ( SFSU) .

Notes:—Described originally from Cameroon, Marasmius somalomoensis is characterized by a tan to pale brown pileus, subdistant (11–14), collariate, non-marginate lamellae, a brown stipe with cortical hyphae that do not turn olive in KOH, basidiospores in the range 7.2–10.4 × 3.2–4.8 μm with mean 8.5 × 3.8 μm, Rotalis - type broom cells, and growth on dicotyledonous leaves. It is nearly indistinguishable from M. colorimarginatus , which differs in forming a darker brown pileus, greyish brown lamellae with brown margins, and stipe cortical hyphae that are olive in KOH.

ITS sequences of the Madagascar material of M. somalomoensis ( KX 149002, KX149003, KX 149004) are more than 3% different from the single available sequence of M. somalomoensis ( EU 935559) derived from a specimen from Thailand ( NW 232), but it should be noted that the Thai material is reported as forming pilei with more reddish brown tones and more lamellae (12–18) with brown edges. It is possible that the Thai material represents a species different from the African M. somalomoensis . ( Fig. 1c ).

Figures

PLATE 1. Basidiocarps representing sect. Marasmius subsect. Marasmius a) Marasmius rotalis (JES 154) b) Marasmius apatelius (JES 203) c) Marasmius somalomoensis (JES 129). Scale bar = 5 mm (a); = 10 mm (b, c). Photography by D.S. Newman.

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 3. Marasmius somalomoensis (JES 129, JES 165, JES 181) a) basidiospores; b) basidioles; c) basidia; d) cheilocystidia; e) pileipellis cells. Scale bar = 10 μm. Illustrated by J.E. Shay.