Marasmius apatelius Singer, Bull. Jard. Bot. État Brux.

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 : 114-115

3. Marasmius apatelius Singer, Bull. Jard. Bot. État Brux. 34: 332. 1964. ( Fig. 4 , Plate 1 )

Type:— DR CONGO, Kisantu, 20 March 1907, H. Vanderyst s.n. ( BR 11377–28, as M. friesianus ).

Description:— Pileus 2–5 mm diam, campanulate to umbilicate, with a dark brown (5 F 4) papilla; margin sulcate to plicate; surface dry, glabrous; greyish orange (5 B 4–5, 6 A – C 2) to buff, dries dark brown. Context thin, buff. Lamellae adnate to a collarium, distant (9–12), broad (2–3 mm), white to orange-white (5 A 2), non-marginate. Stipe 18–54 × <0.5 mm, central, hollow, thin, wiry, insititious; surface glabrous, dark brown (6 F 8). Odor and taste not distinctive.

Basidiospores (7.2–) 8–10.4 (–11.2) × 3.2–4.8 (–5) μm [x mr = 8.9–9.0 × 4.0–4.1 μm; x mm = 8.94 ± 0.02 × 4.02 ± 0.03; Q = 1.8–2.8; Q mr = 2.23–2.25; Q mm = 2.24 ± 0.02, n = 25, s =2], ellipsoid, smooth, hyaline, inamyloid, thin-walled. Basidia 23.2–24.8 × 6.4–8 μm, clavate, 4-spored, hyaline, inamyloid, thin-walled. Basidioles 12–22.4 × 4–8

μm, clavate to fusoid or cylindrical, hyaline, inamyloid, thin-walled. Cheilocystidia abundant, of Rotalis - type broom cells; main body 7.6–23.2 × 8–14.4 μm, globose to subglobose or broadly clavate, hyaline, inamyloid, thin-walled;

divergent setulae 0.5–3.2 × 0.5–2 μm, cylindrical to conical, hyaline, inamyloid, thin-walled. Pleurocystidia absent. Pileipellis not mottled, a hymeniform layer of Rotalis - type broom cells; main body 12–27.2 × 8–27.2 μm, globose to broadly clavate, hyaline, inamyloid, thin-walled; divergent setulae 0.5–2 × 0.5–2 μm, numerous, cylindrical, hyaline to brown, dextrinoid, thin-walled. Pileus trama interwoven; hyphae 1.6–12.8 μm diam, cylindrical to inflated, smooth, hyaline, inamyloid, thin-walled. Lamellar trama regular; hyphae 1.6–8 μm diam, cylindrical to inflated, smooth, hyaline, inamyloid, thin-walled. Stipe tissue monomitic; cortical hyphae 2.4–4 μm diam, parallel, cylindrical, yellow, dextrinoid, thick-walled; medullary hyphae 3.2–6 μm diam, parallel, cylindrical, hyaline, inamyloid, thin-walled. Caulocystidia absent. Clamp connections present.

Habit, habitat and known distribution:—In gregarious clusters on Uapaca littoralis (dicot, Phyllanthaceae ).Africa ( DR Congo, Tanzania, Uganda), Madagascar, Thailand.

Material examined:— MADAGASCAR. Region Atsinanana , District Brickaville , Commune Andevoranto, Andavakimena Forest, elev.- 1 m, GPS: 18˚ 53.231’ S, 49˚ 07.490’ E, 28 January 2014, J. E. Shay 203 ( SFSU) ; Region Vatovavy-Fitovinany , District Ifanadiana , Commune Randomafana , Ranomafana National Park, Piste B, elev. 1004 m, GPS: 21˚ 15.413’ S, 47˚ 25.253’ E, 22 January 2014, J. E. Shay 150 ( SFSU) .

Notes:— Marasmius apatelius is characterized by small (2–5 mm diam), greyish orange to buff pileus, distant (9–12) collariate lamellae, a dark brown, wiry insititious stipe, basidiospores in the range 8–10.4 × 3.2–5 μm with mean 8.9 × 4.0 μm, Rotalis -type broom cells, and growth on dicotyledonous leaves. Described originally from the DR Congo, the Madagascar material matches nicely the African specimens reported by Antonín (2007) and Thai material reported by Wannathes et al. (2009a). An ITS sequence of the holotype of M. andasibensis var. obscurostipitatus Antonín & Buyck ( KX 149005) places the taxon in a clade with M. apatelius ( Fig. 1c ), and differs primarily in several 21–25 base pair insertions. For a comparison with numerous other members of Marasmius sect. Marasmius subsect. Marasmius , refer to Antonín (2007).

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 4. Marasmius apatelius (JES 150, JES 203) a) basidiospores; b) basidia; c) basidioles; d) cheilocystidia; e) pileipellis cells. Scale bar = 10 μm. Illustrated by J.E. Shay.