Marasmius dendrosetosus 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 : 128-130

21. Marasmius dendrosetosus J.E. Shay & Desjardin , sp. nov. ( Fig. 13 , Plate 5 )

MycoBank no.: MB 818619

Holotype:— MADAGASCAR. Region Atsinanana , District Brickaville , Commune Andevoranto, Andavakimena Forest, elev. 0–8 m, GPS: 18˚ 53.231’ S, 49˚ 07.490’ E, 28 January 2014, J. E. Shay 205 ( SFSU).

Etymology:— dendro-setosus –referring to the branched, tree-shaped pileosetae.

Description:— Pileus 2–9 mm diam, convex to plano-convex; disc rugulose; margin smooth; surface dry, glabrous;

cream to orangish white (4A2–3, 5A2–3) or greyish orange (5B3), lighter towards the margin. Context thin (<1 mm),

concolorous. Lamellae adnate, distant (8–12) with 3–6 series of lamellulae, narrow, buff to cream (4A2–3, 5A2–3),

non-marginate. Stipe 3–11 × 0.5–0.8 mm, central, cylindrical, hollow, non-insititious; surface pruinose; apex buff

(4A3, 5A3), centrally light brown (6D5), base dark brown (6F5–7). Odor and taste not distinctive.

Basidiospores 7.2–9.6 (–10.4) × 3.2–4 (–4.8) μm [x mr = 8.2–9.1 × 3.9 μm; x mm = 8.66 ± 0.68 × 3.88 ± 0.02 μm; Q = 1.6–2.8; Q mr = 2.12–2.36; Q mm = 2.24 ± 0.17, n = 7–25; s = 2], ellipsoid, smooth, hyaline, inamyloid, thin-walled. Basidia 20–24 × 6.4–8 μm, clavate, 4-spored, hyaline, inamyloid, thin-walled. Basidioles 16–21.6 × 5.6–7.2 μm,

clavate to fusoid, hyaline, inamyloid, thin-walled. Cheilocystidia abundant, of Siccus - type broom cells; main body

14.4–18.4 × 5.6–7.2 μm, clavate to cylindrical or irregular, seldom 2–3-lobed, hyaline, inamyloid, thin-walled; apical setulae dense, 0.8–1.6 × 0.8–1.6 μm, cylindrical or irregular, sometimes branched, hyaline, inamyloid, thin-walled.

Pleurocystidia absent. Pileipellis mottled, a hymeniform layer of three types of cells: 1) thin-walled Siccus - type broom cells with main body 6–20 × 5.6–8.8 μm, clavate or irregular, seldom 2–3-lobed, hyaline, inamyloid; apical setulae

0.8–8 × 0.8–1.6 μm, cylindrical to conical or irregular, hyaline, inamyloid, thin-walled, branched; 2) thick-walled

Siccus - type broom cells with main body 16.8–21.6 × 5.6–8 μm, clavate, lobed, hyaline, inamyloid; apical setulae 0.8–8

× 0.8–3.2 μm, cylindrical to conical, hyaline, inamyloid, thick-walled; 3) pileosetae 40–300 × 1.6–8 μm, cylindrical to antler-like, often highly branched, clustered, hyaline, inamyloid, thick-walled. Pileus trama interwoven; hyphae 2.4–

7.2 μm diam, smooth, hyaline, dextrinoid, thin-walled. Lamellar trama regular; hyphae 2.4–7.2 μm diam, cylindrical,

smooth, hyaline, inamyloid, thin-walled. Stipe tissue monomitic; cortical hyphae 2.4–7.2 μm diam, parallel, cylindrical,

smooth, light brown to pale yellow, dextrinoid, thick-walled; medullary hyphae 2.4–8 μm diam, parallel, cylindrical,

hyaline, dextrinoid, thin-walled. Caulocystidia of Siccus - type broom cells emerging directly from hyphae; main body 3.2–4 × 1.6–5.6 μm, clavate or irregular, frequently lobed, hyaline, inamyloid, thin-walled; apical setulae cylindrical or irregular, branched, hyaline, inamyloid, thin-walled. Clamp connections present.

Habit, habitat and known distribution:—Solitary or in gregarious clusters on stems and leaves of Uapaca littoralis and Pandanus . Madagascar.

Material examined:— MADAGASCAR. Region Atsinanana , District Brickaville , Commune Andevoranto, Andavakimena Forest, elev. 0–8 m, GPS: 18˚ 53.231’ S, 49˚ 07.490’ E, 28 January 2014, J. E. Shay 205 ( SFSU) ; same location, GPS: 18˚ 53.082’ S, 49˚ 07.559’ E, 30 January 2014, J. E. Shay 211 ( SFSU) .

Notes:— Marasmius dendrosetosus is characterized by a small (<10 mm) smooth cream to orangish white pileus, subdistant non-marginate lamellae, a minutely pruinose stipe, basidiospores in the range 7.2–10.4 × 3.2–4.8 μm, Siccus -type cheilocystidia and caulocystidia, a pileipellis composed of Siccus -type broom cells and scattered hyaline branched pileosetae up to 300 μm long, and growth on dicotyledonous leaves and sticks. Morphology and molecular data indicate that this new species is allied with M. longisetosus J.S. Oliveira & Capelari , describe recently from Brazil ( Oliveira et al. 2014). Marasmius longisetosus differs in forming a more deeply pigmented pileus (yellowish orange to pure orange), slightly longer basidiospores (mean 10.5 μm), and shorter, unbranched pileosetae. ITS sequences of M. dendrosetosus (KX148995, KX148996) are only 95% similar to the holotype specimen of M. longisetosus (JX424040), and align sister to the latter in the ITS phylogenetic analysis (99% BS, 1.0 PP; Fig. 1b ). Marasmius jalapensis Murrill , reported from tropical Africa, is also similar, but forms more crowded lamellae, a longer stipe (40–60 mm), has hymenial setae, shorter and broader pileosetae, and numerous caulosetae ( Antonín 2007).

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 5. Basidiocarps representing sect. Sicci ser. Spinulosi a) Marasmius dendrosetosus (JES 205) b) Marasmius nummularius (JES 124). Scale bar = 10 mm. Photography by D.S. Newman.

FIGURE 13. Marasmius dendrosetosus (JES 205, JES 211) a) basidiospores; b) basidia; c) basidioles; d) cheilocystidia; e) thick-walled pileipellis cells; f) thin-walled pileipellis cells; g) pileosetae and stipe surface broom cells (bottom center). Scale bar = 10 μm. Illustrated by J.E. Shay.