Ganoderma donkii Steyaert, Persoonia
Index Fungorum number: 314312; Facesoffungi number: FoF05650
Basidiome annual to perennial, corky, with distinctly contracted base to host, becoming hard corky to woody hard when dry. Pileus 3–5.5 cm, up to 1 cm thick at the base, suborbicular, plano convex, applanate; upper surface hard, light brown (6D6) to dark brown (6F6), non laccate, distinctly concentrically sulcate zones, crust overlies the pellis, differentiated zone at the point of attachment. Margin 3mm thick, concolorous with the pileus, rounded, inflexed; lower surface yellowish white (4A2) to light brown (6D6). Hymenophore up to 8 mm long, indistinctly stratose, orange grey (6B2), pores circular. Context duplex, not completely homogeneous in color; upper layer dark brown (7F8), pithy, composed of coarse loose fibrils, soft; lower layer light brown (5D4), woody. Basidiospores (n = 25) (6.6)6.7–7.7–8.7(11.3) × (4.2)4.6–5.4–6.2(7.8) μm (Qm = 1.4, Q = 1.1–1.7, with myxosporium). (n = 25) (4.7)4.9–5.8–6.7(7.8) × (2.5)3.2–3.9–4.7(6.2) μm (Qm = 1.4, Q = 1.0–1.8. without myxosporium), ellipsoid, with a yellowish brown (5D8) to brown (6D6) eusporium bearing fine and short echinulae, overlaid by a hyaline myxosporium. Pileipellis a hymeniderm, dark brown (6F8), composed of apically acanthus like branched cells. Context trimitic; generative hyphae (n = 20) (0.5–1.1–2.0) μm in width, colorless, thin-walled; skeletal hyphae (n = 25) (0.9–1.4–1.9) μm in width, light brown (6D6), thick walled, sometimes branched; binding hyphae (n = 25) (0.6–1.0–1.6) μm in width, light brown (6D6), branched, with clamp-connections, intertwined the skeletal hyphae. (Fig. 1)
Habitat: On a living Dipterocarpus tree, accompanied in humus rich soil with over heavily rotted litter on the ground.
Specimens examined: THAILAND, Chiang Mai Province, Mushroom research Center, 19°20′N–98°44′E, elev. 770 m, 21 December 2015, K.K Hapuarachchi (GACP15122107, GACP15122108, GACP151221010, GACP151221012).
Notes: Ganoderma donkii was introduced by Steyaert (1972) from Indonesia and characterized by radially corrugated pileus, hard context and small, ovoid (truncate when mature) basidiospores (7.5–9 × 5.5–7) μm. This species belongs to G. applanatum – australe complex and can be clearly distinguished from G. applanatum and G. australe by having smaller basidiospores (Steyaert 1972, Martinez et al. 1991, Moncalvo & Ryvarden 1997). Ganoderma donkii is distributed in China (Wu & Dai 2005), West Java (Indonesia) (Steyaert (1972) and Thailand (Chandrasrikul et al. 2011). Our collections agree well with the description provided by (Wu & Dai 2005). (from Hapuarachchi et al. 2019)