Ganoderma gibbosum (Blume and T. Nees) Pat. (1897)
Index Fungorum number: IF 250058; Mycobank number: MB 250058; Facesoffungi number: FoF 05652; Fig. 1.
≡ Polyporus gibbosus (Blume and T. Nees)., Nov. Act. Academiae Caesareae Leo‐poldino Carolinae Germanicae Naturae Curiosorum. 13: 19, 4(1–4) (1826)
≡ Fomes amboinensis var. gibbosus (Blume and T. Nees) Cooke,Grevillea. 13(68): 118 (1885)
≡ Fomes gibbosus (Blume and T. Nees) Sacc. Syll. Fung. 6: 156 (1888)
≡ Scindalma gibbosum (Blume and T. Nees) Kuntze., Revisio generum plantarum 3(2): 518 (1898)
Basidiocarps annual or perennial, sessile. Pileus 7–13 cm in length, 4–7 cm in width, and 0.8–1.0 cm thick, usually thick at the base. Pileus shape convex, imbricate, umbonate, uneven, ungulate, somewhat round, and plump when young, broadly attached to its host. Pileus surface non‐laccate (dull), furrowed, sulcate, undulating on the upper surface, somewhat spathulate to uneven, an irregularly ruptured crust overlying the surface, slightly soft at the margin, incised, woody, and cracked when old to older. Pileus colour is usually pale orange (5A3), light orange (5A4), and orange (5A5-7) when young to mature stage, homogenous with pale yellow (1A3), grayish-yellow (1B4–1B6), greyish-green (1C5-8) at the base when developing to mature, extending to greyish-orange (5B3–5B4), yellowish-brown (5D8), brownish-orange (6C4), reddish closed to margin (7A2), and white at the margin of mature fruiting bodies. Context up to 0.4–1.8 cm thick, often reddish brown (8E6-7) to dark brown (8F5-8), compact and hard, tough when dried. Hymenophore reddish-brown (8E7) with shading dark brown (7F6-7). Tube layers 0.3–1.1 cm in length with brown (7D8) to dark brown (7F7). Margin often white (8A1), wavy, and slippery when fresh close to the underside of basidiomes. Pore 4–7 in number per mm, with subcircular to circular. Pore surface usually white (6A1) and turn reddish-brown (8E4-6) when scratched or touched. Hyphal system trimitic hyphal, hyaline, with abundant thick-walled, with clamp connections, hyaline, with walls varying in thickness with simple septa, composed of narrow and sparingly branched; generative hyphae 1.2–3.8 µm broad (n=50), often brownish-orange (6C7) in Melzer’s reagent, thin-walled, hyaline; skeletal hyphae 3.5–4.9 µm broad (n=50), brown (7D8), abundant thick-walled, dextrinoid, mostly hyaline; binding hyphal 2.3–3.9 µm width (n=50), reddish-brown (8E7) in Melzer’s reagent, usually thick-walled, hymenial, branched, mostly dark brown (7F7) near the layer tubes.
Basidiospores ellipsoid to broadly ellipsoid, with some oblong with double walls (4.6-)6.8–8.1–9.1(-10.6)×(5.3-)5.9–6.2–7.4(-8.1) µm (x̅=8.2×6.3 µm, n=50) µm, with Q=1.49–1.57, L=8.24 µm, W=6.27 µm (including myxosporium), (4.8-)5.2–6.1–6.9(-8.2) × (4.2-)4.9–5.6–5.9(-6.7) µm (x̅=6.4×5.7 µm, n=50) µm, with Q=1.08–1.14, L = 6.24 µm, W = 5.67 µm (including myxosporium), overlaid by hyaline, dextrinoid, echinulae, echinulate brown inner wall, light yellow (4A4–4A5) to grayish-yellow (4B5–4B6) in 5% KOH. Basidia not seen.
Material examined – Thailand, Chiang Rai Province, Muang District, Thasud, 20°2′50′′N, 99°53′44′′E, 20 m, 25 May 2022, T. Luangharn, LT2022-096, MFLU23-0017.
Host and habitat – solitary on the dead stump of a Bauhinia variegate tree.
GenBank numbers – ITS: OQ383906; LSU: OQ383907.
Notes – Ganoderma gibbosum was initially documented in Java; however, the original specimen has been regrettably misplaced (Moncalvo and Ryvarden 1997). This species has been synonymous with non-laccate G. applanatum, which is classified in the G. applanatum–australe complex (Moncalvo and Ryvarden 1997). Ganoderma gibbosum is widely distributed in both tropical and temperate regions. Species of this genus can be pathogens or saprobes on a wide range of hosts (Luangharn et al. 2020, 2021). Ganoderma gibbosum is characterized by its non-laccate basidiomes, annual or perennial, sessile, furrowed and sulcated to undulating, and ellipsoids with double-walled basidiospores. Luangharn et al. (2020) reported the Chinese collections of G. gibbosum and host preferences from Kunming, China. Phylogenetic analysis (Fig. 2) and macro–micro morphological characteristics examined largely overlap with those of G. gibbosum reported by Luangharn et al. (2020). In this study, we illustrate the macro- and micro-characteristics and molecular evidence of G. gibbosum, through its new host record of Bauhinia variegate from Thailand.
Figure 1 – Ganoderma gibbosum (MFLU23-0017, new host record). a, b Mature basidiocarps on host. c Underbasidiocarp. d Pore characteristics. e Tube layer hyphae in Melzer’s reagent. f–h Contaxt hyphae. i, j Basidiospore. Scale bars: a–c=5 μm, d=500 μm, f=10 μm, g–h=20 μm, i–j=5 μm
Figure 2 – Maximum likelihood phylogenetic tree ML obtained from the DNA sequence data of the ITS and LSU data sets. Bootstrap values of maximum likelihood ML in the left, MP in the middle, equal to or greater than 70%, and Bayesian posterior probabilities PP in the right, equal to or greater than 0.95, are indicated above or below the nodes as MLBS/MPBS/PP. The tree is rooted with Tomophagus colossus TC‐02. A known species obtained in this study is indicated in bold