Marasmius rubrobrunneus 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 : 119-120

12. Marasmius rubrobrunneus J.E. Shay & Desjardin , sp. nov. ( Fig. 7 , Plate 2 )

MycoBank no.: MB818617

Holotype:— MADAGASCAR. 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 191 ( SFSU).

Etymology:— rubro –reddish, - brunneus –brown, referring to the dark reddish brown pileus.

Description:— Pileus 4–9 mm diam, campanulate, umbilicate, with a dark brown papilla; margin sulcate; surface glabrous; dark reddish brown (7–8E–F5–8). Context thin, dark reddish brown. Lamellae adnate to a collarium, distant (11–12), broad, no lamellulae; white to buff (4A2) with reddish brown edges. Stipe 16–26 × <0.5 mm, central, hollow, twisted, wiry, insititious; surface glabrous; dark brown. Odor and taste not distinctive.

Basidiospores (12–) 13.6–19.2 × 2.4–4 μm [x mr = 14.9–16.5 × 3.2 μm; x mm = 15.71 ± 1.13 × 3.2 ± 0.06; Q = 2.8–6.7; Q mr = 4.6–5.18; Q mm = 4.89 ± 0.41, n = 25, s = 2], narrowly fusoid, smooth, hyaline, inamyloid, thin-walled. Basidia not observed. Basidioles 17.6–26.4 × 4.8–7.2 μm, clavate to fusoid, hyaline, inamyloid, thin-walled. Cheilocystidia abundant, of Siccus - type broom cells ; main body 12–20 × 6.4–8 μm, clavate to cylindrical or subglobose, seldom bilobed, light brown, inamyloid, thick-walled; apical setulae 0.8–4.8 × 0.8–2.4 μm, cylindrical to conical, sometimes branched, light brown, inamyloid, thick-walled. Pleurocystidia absent. Pileipellis mottled, a hymeniform layer of

Siccus - type broom cells; main body 9.6–19.2 × 6.4–12 μm, clavate to cylindrical or subglobose, brown to hyaline,

inamyloid, thick-walled; apical setulae 0.8–6.4 × 0.8–2.4 μm, cylindrical to conical, obtuse, seldom branched, brown to hyaline, inamyloid, thick-walled. Pileus trama interwoven; hyphae 3.2–8.8 μm diam, smooth, hyaline, inamyloid,

thin-walled. Lamellar trama regular; hyphae 2.4–16 μm diam, cylindrical, smooth, hyaline, inamyloid, thin-walled.

Stipe tissue monomitic; cortical hyphae 2.4–8 μm diam, parallel, cylindrical, smooth, light brown to brown, dextrinoid,

thick-walled; medullary hyphae 4–10.4 μm diam, parallel, cylindrical, smooth, light yellow to hyaline, inamyloid,

thin-walled. Caulocystidia absent. Clamp connections present.

Habit, habitat and known distribution:—Solitary or in small gregarious clusters on a variety of leaf litter and stems of Uapaca densifolia ( Phyllanthaceae ), Canarium boivinii ( Burseraceae ), Pandanus, Contium and other unknown dicots. Madagascar.

Material examined:— MADAGASCAR. 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 191 (SFSU) &

J.E. Shay 183 (SFSU).

Notes:—Features of Marasmius rubrobrunneus include a small (4–9 mm diam), sulcate, dark reddish brown pileus, distant collariate lamellae with reddish brown edges, a black wiry insititious stipe, basidiospores with mean

15.7 × 3.2 μm (Q m = 4.9), Siccus - type broom cells, and growth on dicotyledonous leaves and twigs. Morphologically, the new species is nearly indistinguishable from M. purpureobrunneolus Henn. , described originally from Java. The latter species has been redescribed several times ( Desjardin et al. 2000, Tan et al. 2009, Wannathes et al. 2009a)

from material collected in southeast Asia, and is distinguished by a dark purplish brown pileus and basidiospores in the range 12–17 (–19) × 2.5–5 μm, with means in the range 14.0–14.8 × 3.2–4.1μm (Q mr = 3.6–4.5). In comparison, Marasmius rubrobrunneus has a dark reddish brown pileus lacking purple tones, and basidiospores with means in the range 14.9–16.5 × 3.2 μm, i.e., slightly longer and narrower than in M. purpureobrunneolus . Although this variability may seem trivial, a comparison of the ITS sequence of the Madagascar holotype specimen (KX148989) with two specimens of M. purpureobrunneolus from Thailand (EU935556, EU935557) show only 85% similarity. In the ITS phylogenetic analysis ( Fig. 1c ), M. rubrobrunneus is sister to M. purpureobrunneolus with good support (81% BS; 1.0

PP).

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.

PLATE 2. Basidiocarps representing sect. Marasmius subsect. Sicciformes a) Marasmius conicopapillatus (JES 180) b) Marasmius aff. curreyi (JES 135) c) Marasmius rubrobrunneus (JES 183). Scale bar = 5 mm (a); = 10 mm (b, c). Photography by D.S. Newman.

FIGURE 7. Marasmius rubrobrunneus (JES 183, JES 191) a) basidiospores; b) basidioles; c) cheilocystidia; d) pileipellis cells. Scale bar = 10 μm. Illustrated by J.E. Shay.