Marasmius jinfoshanensis Chun Y. Deng & Gafforov sp. nov.

Index Fungorum number: IF 836094; MycoBank number: MB 836094; Facesoffungi Number: FoF 09969; Figs. 1, 2

Etymology – Referring to the Jinfoshan National Nature Reserve, the location where the type specimen was collected.

Holotype – HGASMF 01–4344

Pileus 3–5 mm, convex to broadly conical, umbonate; glabrous; greyish orange (5B4, 5B5, 6B5), light brown (7D5), brownish orange (6C6, 7C6, 7C4), at center with a surrounding white dot. Lamellae subdistant, L=12–16, l=0, collariate, pale cream, with a concolorous edge. Stipe up to 60–80 mm long, filiform, insititious, smooth, glabrous, white at apex, reddish brown (7E8, 8E8) to dark brown (7F7, 8F8) to black. Basidiospores (6.5–)7–8(–9.8)×4–5 µm, E=1.6–2, Q=1.7, ellipsoid, sublacrymoid, ellipsoid-fusoid, thin-walled, smooth, hyaline, inamyloid. Basidia 19–27 × 9–11 µm, 4-spored, clavate. Basidioles 12–28 × 4–9 µm, clavate, cylindrical, fusoid. Cheilocystidia in the form of broom-cells of the Rotalistype, 20–30×5–8 µm, clavate, subcylindrical, thin-walled, with±thin-walled or slightly thick-walled, projections. Pleurocystidia absent. Trama hyphae cylindrical to subinflated, thin-walled, hyaline, dextrinoid, up to 12 µm wide. Pileipellis a hymeniderm consisting of broom-cells of the Rotalistype, 13–18×7–14 µm, clavate, subvesiculose, pyriform, thin-walled, sometimes with slightly thick-walled apex, with cylindrical to warty, up to 2×1 µm large projections. Stipitipellis a cutis composed of cylindrical, parallel, slightly thick-walled, smooth, up to 5 µm wide hyphae with yellowish walls in KOH; medulla hyphae slightly dextrinoid. Caulocystidia absent. Clamp connections present in all tissues.

Material examined – CHINA, Chongqing, Nanchuan district, Jinfoshan National Nature Reserve, N107.182222, E29.030152, 2 037 m alt., 6 Apr. 2020, C.Y. Deng, DCY 2409 (HGASMF 01–4344, holotype); ibid., 6 Apr. 2020, C.Y. Deng, DCY 2413, (HGASMF 01–4345, paratype).

GenBank numbers – HGASMF01–4344: ITS=MT556448, LSU=MW237220; HGASMF 01–4345: ITS=MT556449, LSU=MW237221.

Notes – Marasmius sect. Marasmius species are unique because they have collariate lamellae (Singer 1976, 1986; Desjardin 1989; Antonín 1991, 2007; Antonín and Noordeloos 2010). Based on nrITS sequences, subsect. Maramius is monophyletic while subsect. Sicciformes is paraphyletic (Tan et al. 2009; Wannathes et al. 2009). Marasmius subsect. Horriduli might have a wider range (de Oliveira et al. 2020). Marasmius jinfoshanensis is in Marasmius sect. Marasmius because it has collariate lamellae. ITS and LSU dataset of M. siccus were chosen as an outgroup for rooting purposes based on a study by Tan et al. (2009) and Wannathes et al. (2009). Two sequences of M. jinfoshanensis constitutes a subclade on a long branch with 100% bootstrap support. Marasmius jinfoshanensis is sister to Marasmius wisteriae with high support. Marasmius wisteriae was described from Korea. It differs from other Maramius species by a pale colored pileus with a dark central dot and large, clavate-fusoid, fusoid, narrowly lacrymoid basidiospores (Antonín et al. 2013). Two sequences of Marasmius rotalis (KC415765 and JN003837) were likely misidentified. Marasmius capillaris is represented on two separate branches in our phylogeny (Fig. 3). Both species were collected in two different states in North America. At least one of these species must be misidentified.

Figure 1 – Marasmius jinfoshanensis (HGASMF 01-4344, holotype): Basidiomata of on decaying leaves of dicotyledons in the litter in a subtropical-montane forest

Figure 2 – Marasmius jinfoshanensis (HGASMF 01-4344, holotype): Microscopic structures. a Basidiospores. b Basidia. c Cheilocystidia. d Pileipellis. Scale bar: d=10 μm

Figure 3 – Maximum likelihood tree inferred from ITS-LSU nrDNA, using RAxML GUI v. 2.0.0 (Edler et al. 2020), showing the placement of Marasmius jinfoshanensis. Support values (>50% with 1,000 replicates) are shown above branches. Marasmius ruforotula (FJ936150, FJ936152, MK278352) and M. siccus (FJ904985, JN943596) were chosen as outgroup. Ex-type strain is in bold and newly generated sequences are in blue