Marasmius yunnanensis Q.Y. Zhang, J. Si & H.J. Li, 2023

Zhang, Qiu-Yue, Si, Jing & Li, Hai-Jiao, 2023, A new Marasmius species (Agaricales, Marasmiaceae) with sessile basidiomata growing on wood, from Yunnan, China, Phytotaxa 578 (2), pp. 169-179 : 175-176

Marasmius yunnanensis Q.Y. Zhang, J. Si & H.J. Li , sp. nov. ( Figs. 2–3 )

MycoBank no.:—846815

Etymology:— yunnanensis (Lat.) : refers to the type locality of Yunnan Province, southwest China.

Habitat and distribution:—gregarious on fallen angiosperm branch in tropical forest.

Diagnosis:—Differs from other Marasmius species by the tiny basidiomata, sessile or short, inconspicuous stipe, and interwoven and anastomosing to subreticulate lamellae.

Type:— CHINA. Yunnan Province: Honghe , Pingbian County, Daweishan Natural Forest Park , on fallen angiosperm branch, 26 June 2019, Dai 19782 (holotype, BJFC 031457 ) .

Description:— Basidiomata annual, gregarious. Pileus conchoidal, reniform to semicircular, 1.6–2.4 mm in diameter, convex to applanate; pileal surface cinnamon to cream when fresh, becoming clay-buff upon drying, dry, dull, striate to sulcate, minutely pruinose; context concolorous with pileal surface, thin. Hymenophore concolorous with pileal surface, lamellate; lamellae adnexed, interwoven and anastomosing to subreticulate, irregularly convex, collarium complete, distinct to indistinct in sessile basidiomata, incomplete, distinct in stipitate basidiomata; lamellae surface powdery. Stipe none, or short and inconspicuous. Odor and taste not distinctive.

Basidiospores (7.2–)8–10 × 5–6.2(–6.3) μm, L = 8.80 μm, W = 5.83 μm, Q = 1.50–1.52 (n = 60/2), ellipsoid, hyaline, thin-walled, smooth, with some guttules, IKI–, CB–. Basidia 24–30 × 6–8 µm, clavate, with a few guttules, 2(–4)-spored, sterigmata 1–2 μm long; basidioles numerous, lanceolate to clavate. Cheilocystidia abundant, of two types, the first type dominant, 12–30 × 8–16 µm, as Rotalis - type broom cells, slightly thick-walled, broadly clavate to pyriform, or turbinate, or irregular, with abundant apical diverticula, often wart-like, some short and digitiform, 1–2 × 0.5–1 μm; the other type, 9–32 × 6–10 µm, smooth, slightly thick-walled, clavate to pyriform. Pleurocystidia not observed. Pileipellis composed of a hymeniform layer of smooth or Rotalis - type broom cells; terminal cells 19–40 × 12–20 μm, in shape similar to cheilocystidia, oriented perpendicular to pileal surface. Hymenophoral tramal hyphae subparallel, hyaline, some partly swollen, thin-walled, 3–7 μm in diameter. Clamp connections present in all tissues. Trama, stipe medulla and stipitipellis hyphae are slightly dextrinoid.

Additional specimen examined (paratype):— CHINA. Yunnan Province: Honghe, Pingbian County, Daweishan Natural Forest Park , on fallen angiosperm branch, 26 June 2019, Dai 19857 ( BJFC 031532 ) .

Figures

FIGURE 2. Basidiomata of Marasmius yunnanensis. (A, B from paratype, Dai 19857; C, D from holotype, Dai 19782). Photos by: Qiu- Yue Zhang.

FIGURE 3. Microscopic structures of Marasmius yunnanensis (Dai 19782, holotype). a Basidiospores. b Basidia and basidioles. c Cheilocystidia. d Hyphae from pileipellis, including terminal cell. e Section of lamellae trama, showing cheilocystidia, basidia and basidioles. Drawings by: Qiu-Yue Zhang.