Marasmius blandus J. Q. Yan & H. Chen sp. nov.

Fig. 2

Etymology.

“blandus” refers to its smooth and non-striate pileus.

Holotype.

China • JiangXi Province, Jiangxi Agricultural University, 6 October 2020, collected by Jia-Yue Sun, HFJAU 2362.

Diagnosis.

Marasmius blandus is mainly characterized by the rather small basidiomata, light orange pileus, with a non-striate surface; basidiospores mainly shorter than 7.5 μm; variably shaped pleurocystidia, subfusiform, narrowly utriform, with a short or long papilla at the apex and rarely with nodulose on the surface; cheilocystidia clavate, subfusiform, apex obtuse, rarely with short papilla or branched. It differs from M. brunneospermus by having smaller cheilocystidia, which are mainly shorter than 30 μm in length.

Description.

Pileus 25–50 mm, plano-convex to plane, with or without a slight obtuse umbo at the center, smooth, non-striate, hygrophanous, light orange (6 A 5–6) at center, slightly paler to white towards margin, drying out to white, the center and the margin with pale brown. Context thin, white. Lamellae 3.0–5.0 mm broad, adnexed, ventricose, subdistant, white with slightly brown, with 2–3 tiers of lamellules, edges even, concolorous. Stipe 20–50 mm long, 2.0–3.0 mm thick, central, cylindric, equal, fibrous, hollow, light yellow (4 A 3–4), becoming reddish brown (8 D 5–6) as stipe dries, smooth, apex velutinous, and the base covered with white mycelium.

Basidiospores (5.0) 5.5–7.5 (8.0) × 2.4–3.5 μm (av = 6.5 × 3.0 μm), Q = (1.6) 1.8–2.6 (3.0), elongated-ellipsoid to cylindrical, slightly flattened on one side in profile, 2.4–4.0 μm broad, elongated-ellipsoid to cylindrical in face view, smooth, colorless, hyaline, inamyloid, thin-walled. Basidia 24.0–30.5 × 4.0–6.5 μm, clavate, 4 - spored. Pleurocystidia 37.0–80.0 × 7.5–18.0 μm, variable, subfusiform, narrowly utriform, apex with short or long papilla, surface rarely with nodulose, smooth, slightly thick-walled, yellowish in 5 % KOH. Cheilocystidia 18.5–31.0 (38.0) × 5.0–15.5 μm, variable, clavate, subfusiform, apex obtuse, rarely with short papilla or branched, smooth, thin-walled. Pileipellis a hymeniderm composed of cells 16.5–31.5 × 7.0–16.0 μm, pyriform or broadly clavate, smooth, hyaline, thin-walled. Lamellae trama interwoven, with hyphae 4.0–6.5 μm in diam, hyaline, dextrinoid, thin-walled. Stipitipellis a cutis composed of cylindrical hyphae, 4.0–9.5 μm wide, parallel, smooth. Caulocystidia absent. Clamp connections present.

Habitat.

Scattered on soil in broad-leaved forest or mixed coniferous and broad-leaved forests.

Additional specimens examined.

China • JiangXi Province, Jiangxi Agricultural University, 1 May 2019, collected by Jia-Yue Sun, HFJAU 3367; 23 May 2023, collected by Lin-Gen Chen, Cheng-Feng Nie HFJAU 4946; Hubei Province, Xingshan County, Yichang City, 23 July 2024, collected by Jun-Qing Yan, Lin-Gen Chen, Hong Chen, Ling Ding, HFJAU 5635.

Note.

Based on molecular systematics and morphological analysis, M. blandus belongs to subg. Globulares ser. Brunneospermi (Oliveira et al. 2020 b; Oliveira et al. 2024), within this series, M. blandus is morphologically similar to M. brunneospermus, M. fusicystidiosus, and M. macrocystidiosus. However, M. brunneospermus has an irregularly wrinkled to rugulose reticulate pileus and larger cheilocystidia (30–57 × 4–13 μm) (Takahashi 1999); M. fusicystidiosus differs in the reddish ochre-brown pileus at the center, slightly paler towards margin and larger basidiospores (8.5–10 × 3.5–4.0 μm) (Antonín et al. 2010 a); M. macrocystidiosus is distinguished from M. blandus by a light brown or grayish brown pileus, larger basidiospores (6.9–10.5 × 3.3–4.4 μm) and larger pleurocystidia (78.3–123.0 × 12.5–13.8 μm) (Kiyashko et al. 2014).

In addition, morphologically, among the known species of sect. Globulares, only M. desjardinii K. Das, Antonín & D. Chakr., M. muramwyanensis Antonín, M. goossensiae Beeli, and M. phlebodiscus Desjardin & E. Horak. share similar morphological characteristics with the new species M. blandus, including a hymenidermal pileipellis composed of Globulares - type cells, the basidiospores range in size from 5.0–8.0 × 2.0–4.0 μm, and have the well-developed pleurocystidia. However, M. desjardinii differs from M. blandus by a longer stipe (70–180 × 4–10 mm), grayish orange to apricot pileus when dry, pleurocystidia sometimes lageniform and possesses pileocystidia (Das et al. 2019); M. muramwyanensis differs by having a stipe white at apex, ochraceous to brownish-orange at base, pleurocystidia cylindrical, clavate, fusoid (Antonín 2003); M. goossensiae differs from M. blandus in forming a cream colored pileus with fuligineous or ochraceous brown centre, clavate, and rostrate pleurocystidia (Antonín 2007); M. phlebodiscus has a pale beige to tan colored pileus with reticulate wrinkles at center and only fusoid pleurocystidia, fusoid and mucronate cheilocystidia (Petrini et al. 1997).