Marasmius centrocinnamomeus J.S. Kim & Y.W. Lim, sp. nov.
Index Fungorum number: IF 900042; Mycobank number: MB 900042; Facesoffungi number: FoF 13254; Fig. 1
Etymology – ‘centrocinnamomeus’ refers to the cinnamon (bright brown) colored center of pileus.
Holotype – SFC20180704-02.
Pileus 12–67 mm in diam, convex to campanulate when young, becoming plano-convex to uplifted when old, sometimes slightly depressed in or near the center, rugulose, glabrous, hygrophanous, greyish orange (5B5) to brown (6E6) when moist, yellowish white (3A2) to greyish yellow (4B6), margin white to yellowish white (3A2 to 4A2). Lamellae adnexed, distant (L=12–22), with 1–3 series of lamellulae, white to yellowish white (3A2 to 4A2), concolorous with margin. Stipe 30–110×11–50 mm, central, cylindrical, greyish yellow (4B4) to orange white (5A2) toward apex, brownish orange (5C4) to light brown (6D5) towards the base, non-insititious, with whitish basal mycelium.
Basidiospores (5.8–)6.1–8(–8.7) × 3.4–4.6(–5.1) μm (x̅= 7.1 × 4 μm, n/s = 30), Q = 1.3–2.1 (x̅= 1.78), asymetrical, ellipsoid to oblong, hyaline, inamyloid, thin-walled, sometimes with oil drops. Basidia (29–)31.2–3 8.8(–42) × 5.4–7.3 μm, cylindrical, clavate. Basidioles 20–37 × 3.3–7 μm, cylindrical, fusoid, clavate, hyaline, thin-walled. Pleurocystidia absent. Cheilocystidia (18–)20–3 2.5(–37)×(5.5–)6–9.9(–11) μm, (broadly) clavate, obovoid, hyaline, thin- to slightly thick-walled. Tramal hyphae formed by cylindrical or sometimes inflated, thin walled, hyaline, up to 12 μm wide. Pileipellis a hymeniderm composed of cells 13.5–26×7–17 μm, broadly clavate to sphaeropedunculate, vesiculate, thin- to slightly thick-walled, smooth, yellowish white (1A2) in KOH. Stipe tramal hyphae 3–7(–7.6) μm broad, cylindrical, hyaline, moderately dextrinoid, slightly
thick-walled. Caulocystidia (13–)14.5–38(–41) × (4.5–)5 .2–8.5(–9.3) μm, abundant, cylindrical to clavate, fusoid, branched, hyaline, inamyloid, thin-walled. Clamp connections present in all tissues.
Material examined – Republic of Korea, Jeollanamdo, Wando-gun, cedar Recreation Forest, 34°20′47.4″N 126°40′14.4″E, on leaf litter dominated with pine needles, 4 July 2018, Young Woon Lim, SFC20180704-02 (holotype); Jeju island, Jeolmul Natural Recreation Forest, 33°26′22.7″N 126°37′34.7″E, on leaf litter, 3 July 2014, Jae Young Park (SFC20140703-03); Incheon, Ganghwa-gun, Manisan, 37°36′41.8″N 126°26′05.4″E, on leaf litter in a mixed forest dominated with Carpinus laxiflora, 16 July 2015, Jae Young Park, SFC20150716-07; Incheon, Ongjin-gun, Jangbongdo, 37°32′20.7″N 126°20′12.0″E, on leaf litter of broadleaf tree, 26 July 2016, Nam Kyu Kim, SFC20160726-33.
Habitat – On litter in a mixed forest of conifer and broadleaf trees.
GenBank numbers – SFC20180704-02: ITS=OP730947; SFC20140703-03: ITS=OP730948; SFC20150716-07: ITS=OP730949; SFC20160726-33: ITS=OP730946.
Notes – The diagnostic characteristics of Marasmius centrocinnamomeus are convex to plano-convex and brownish pileus, adnexed and distant lamellae, central, cylindrical, greyish yellow to light brown colored, non-insititious stipe that becomes brownish toward the base, ellipsoid to oblong basidiospores, (broadly) clavate to obovoid cheilocystidia, and a hymeniderm pileipellis composed of broadly clavate to sphaeropenduculate cells. Marasmius maximus is morphologically similar species and phylogenetically close species to M. centrocinnamomeus (Fig. 2). However, Marasmius maximus differs from M. centrocinnamomeus by shorter stipe with a darker brownish base, larger basidiospores, and bigger caulocystidia (Hongo 1962; Antonín et al. 2010).
Figure 1 – Basidiomes and microscopic drawings of Marasmius centrocinnamomeus (SFC201807014-02, 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