Marasmius ferrugineodiscus J.S. Kim & Y.W. Lim, sp. nov.
Index Fungorum number: IF 900041; Mycobank number: MB 900041; Facesoffungi number: FoF 13255; Fig. 1
Etymology – ‘ferrugineodiscus’ refers to the light brown color of the center of the pileus.
Holotype – SFC20160714-57.
Pileus 15–30 mm in diam, convex when young, becoming plano-convex to undulate when old, sometimes slightly depressed in center, wrinkled, glabrous, orange grey (5B2), greyish orange (5B5) to light brown (6D4), margin yellowish grey (4B2) to greyish orange (5B3), hygrophanous. Lamellae adnexed to sinuate, subdistant (L=20–32), with 2–4 series of lamellulae, white with concolorous edge. Stipe 23–68×1.3–3 mm, central, cylindrical, hollow, brownish orange (5B4), grayish brown (5D3) to brownish orange (6C3) towards base, yellowish grey (4A2) to orange grey (5B2) towards apex, non-insititious, with whitish basal mycelium.
Basidiospores 5.4–7.8 (–8.4) × 2.7–4(–4.5) μm (x̅=6.7×3.5 μm, n/s=30), Q=1.6–2.6 (x̅=1.98), oblong to amygdaliform, hyaline, inamyloid, thin-walled, with oil drops. Basidia 26.3–30.8×3.5–6 μm, cylindrical, (narrowly) clavate. Basidioles 19.2–29.4×2.8–5.6(–6) μm, cylindrical, fusoid to narrowly clavate, hyaline, thin-walled. Pleurocystidia absent. Cheilocystidia 16–27 × (5.4–)5.7–12.6 μm, variable in shape, (broadly) clavate, pyriform, obovoid, branched, hyaline. Tramal hyphae formed by cylindrical, slightly thick-walled, hyaline, up to 12 μm wide cells. Pileipellis a hymeniderm composed of cells 15.6–22.3 × 8.7–17.5 μm, ellipsoid, (broadly) clavate, obovoid, vesiculate, thin-walled, smooth, yellowish white (1A2) in KOH. Stipe tramal hyphae 3.5–9.2(–11) μm broad, cylindrical to fusoid, hyaline, strongly dextrinoid, slightly thick-walled. Caulocystidia 20–42×5.5–12 μm, sometimes clustered, cylindrical to clavate, hyaline, inamyloid, slightly thin-walled. Clamp connections present in all tissues.
Material examined – Republic of Korea, Gyeongsangbukdo, Ulleung-gun, Ulleung-eup, 37°30′44.4″N 130°54′31.1″E, on the decomposed branch, 14 July 2016, Jae Young Park, SFC20160714-57 (holotype); Seoul, Gwanak-gu, Seoul National University, 37°27′51.8″N 126°57′08.0″E, on leaf litter, 21 August 2014, Jae Young Park, SFC20140821-08; Incheon, Ongjin-gun, Yeongheung-myeon, 37°15′25.0″N 126°27′37.1″E, on leaf litter, 19 July 2016, Nam Kyu Kim, SFC20160719-13.
GenBank numbers – SFC20160714-57: ITS=OP730950; SFC20140821-08: ITS = OP730951; SFC20160719-13: ITS=OP730952.
Habitat – On litter of leaves and branches in a mixed forest of conifer and broadleaf trees.
Notes – Marasmius ferrugineodiscus is characterized by a convex to undulate pileus which is orange grey to light brown colored center but gets whiter as it goes to margin, subdistant and adnexed lamellae, central and cylindrical stipe, oblong to amygdaliform basidiospores, (broadly) clavate to pyriform cheilocystidia, and a hymeniderm formed pileipellis composed of clavate, obovoid, vesiculate cells. These characteristics place this species under sect. Globulares. The macromorphological characteristics of this species are similar to Marasmius wynneae. Marasmius wynneae has more whitish and greyish pileus when comparing with M. ferrugineodiscus. Marasmius ferrugineodiscus is phylogenetically close to Marasmius albimyceliosus (Fig. 2). However, M. albimyceliosus can be distinguished from M. ferrugineodiscus by pale cream pileus, fewer lamellae, and the lack of caulocystidia (Wannathes et al. 2009).
Figure 1 – Basidiomes and microscopic drawings of Marasmius ferrugineodiscus (SFC20160714-57, holotype). A Field pictures of the basidiomes, B Drawings of the microscopic features. Abbreviations: s Basidiospores. b Basidia. ch Cheilocystidia. p pileipellis cells. ca Caulocystidia. Scale bars: A=1 cm, B=20 μm
Figure 2 – Phylogenetic tree conducted from maximum likelihood analysis based on ITS sequence data of Marasmius species with Bayesian Information Criterion values. Related sequences are mostly taken from Oliveira et al. (2020). A total of 49 Marasmius and two Crinipellis species as outgroup taxa are included in the phylogenetic analysis. Crinipellis malesiana and Crinipellis brunneipurpurea are used as the outgroup taxa. Support values at the nodes consist of BS over 70 and PP over 0.95. The nodes with 100 BS are represented as thicker stems. The sequences obtained in this work are indicated in blue