Ganoderma artocarpicola

Ganoderma artocarpicola J. He and S.H. Li

MycoBank number: MB845720

Basidiomata: annual, sessile and broadly attached, usually concrescent, woody hard. Pileus: imbricate, flabelliform to reniform, slightly convex to applanate, projecting up to 9 cm, 8 cm wide and 2 cm thick at the base. Pileus surface reddish brown (9E8) to yellowish brown (5C7), weakly to strongly laccate, with shallowly concentric furrows and radial rugose, concentrically zonate or azonate. Margin: buff (1A3) to grayish orange (6D8), entire, obtuse, irregularly wavy. Context: up to 1.8 cm thick, heterogeneous, the upper layer greyish white(2B1), the lower layer cinnamon brown (6D7) to chestnut brown (8E5), without black melanoid lines, hard corky and fibrous. Tubes: 0.2–0.5 cm long, dark brown (6E8), woody hard, unstratified. Pores: 5–7 per mm, circular to angular, dissepiments thick, entire; pores surface cream (2B2) to greyish white (2B1) when fresh, golden grey to greyish brown when bruising and drying. Hyphal system trimitic: generative hyphae 2.0–3.5 μm in diameter, colorless, thin-walled, with clamp connections; skeletal hyphae 2.0–5.0 μm in diameter, thick-walled with a narrow lumen to sub-solid, arboriform and flexuous, pale yellow to yellowish brown; binding hyphae 1.5–3.0 μm in diameter, thick-walled, frequently branched, interwoven, colorless, scarce; all the hyphae IKI–, CB+; tissues darkening in KOH. Pileipellis: a crustohymeniderm, cells 35–50 × 5–10 μm, thick-walled to sub-solid, apical cells clavate, inflated and flexuous, pale yellow to golden yellow, without granulations in the apex, moderately amyloid at maturity. Basidiospores: ellipsoid to ovoid, not obviously truncated, with apical germ pore, yellowish to golden yellow, IKI–, CB+, inamyloid; double walled with slightly thick walls, exospore wall smooth, endospore wall with inconspicuous spinules; (60/3/2) 8.0 (8.5)–9.3–10.0 (10.5) × 5.0 (5.5)–6.2–7.0 (7.5) μm, L = 9.25 μm, W = 6.20 μm, Q = (1.23) 1.31–1.50–1.72 (1.78), Qm = 1.50 ± 0.14 (including myxosporium). Basidia: barrel-shaped to utriform, colorless, with a clamp connection and four sterigmata, thin-walled, 10–15 × 5–9 μm; basidioles pear-shaped to fusiform, colorless, thin-walled, 8–10 × 4–7 μm.

Specimen examined: CHINA, Yunnan Province, Lincang City, Yongde County, Dedang Town (24°01′12″N, 99°15′34″E), on a living tree of Artocarpus pithecogallus, alt. 1,484 m, Qian-Qiu Luo, 22 August 2021, HL173 (HKAS 123783).

Notes: In the phylogenetic analyses, G. artocarpicola is sister to G. bubalinomarginatum, which was described from the southwest Guangxi Province in China (Figure 3; Sun et al., 2022). Morphologically, both species share similar characteristics of the connate and sessile basidiomata, reddish brown to yellowish brown pileus surface, and non-stratified tubes. However, G. bubalinomarginatum differs from G. artocarpicola in having buff and obtuse pileus margin, smaller basidiospores (7.0–8.8 × 4.3–5.8 μm), and larger basidia (15–22 × 7–11 μm, Sun et al., 2022). Ganoderma weberianum and G. artocarpicola are similar in having imbricate, sessile and hard basidiomata. However, G. weberianum has a pale-yellow pore surface when dry, homogeneous greyish brown context, smaller basidiospores (6.0–7.0 × 4.0–6.0 μm), and longer pileipellis (60.0–90.0 × 6.0–12.0 μm, Steyaert, 1972; Pan and Dai, 2001). In addition, the pileus of G. weberianum is more laccate than G. artocarpicola. The comparison of the ITS sequences of G. weberianum and G. artocarpicola showed 2.12% (13/614 bp) nucleotide differences.

Fig. 1 Maximum likelihood (ML) tree generated from a combined ITS + nrLSU sequence dataset. Bootstrap support values of maximum likelihood (ML) equal to or greater than 60% and Bayesian posterior probabilities (PP) equal to or greater than 0.90 are given above the nodes as “ML/PP.” New collections are indicated in black bold and new species are in red bold.