Phylogeny
Phylogenetic analyses were conducted using the combined dataset, including the ITS, RPB2, and TEF1 sequences of 36 taxa. These sequences belong to the genus Ganoderma and were grouped into six clades. Reference sequences were obtained from GenBank (from samples collected in the USA, UK, Czech Republic, France, Italy, Korea, China, Japan, Netherlands, Thailand, and Vietnam) with holotypes (G. lingzhi, G. leucocontextum, and G. multipileum). Tomophagus colossus (Fr.) Murill 1905 (TC-02, Vietnam) is the outgroup of the taxonomic tree. The dataset comprised 2176 sites with gaps (558 sites for ITS, 946 sites for RPB2, and 672 sites for TEF1). Tree topologies resulting from the ML analysis were similar to the Bayesian analysis. The best-scoring ML tree and Bayesian analysis are shown in Fig. 1. The results showed that specimens collected from Vietnam clustered significantly, forming a monophyletic group with the G. multipileum taxon, including the holotype (CWN 04670) and other sequences from China (Cui 14373, Dai 9447) and Thailand (MLU 19-2166), with high ML/PP support values (100% and 1.00, respectively).
Taxonomy
Habitat: G. multipileum VNHCM1805 lived on the roots and trunk of a royal poinciana tree (D. regia, Fabaceae). When the basidiocarps were observed in November 2018, the tree bloomed thereafter in May 2019. In contrast, the tree was no longer flowering in May 2020 and its leaves were lost, with branches dying back until May 2021 (Fig. 2).
Basidiome
annual, stipitate, laccate, woody. Pileus 15–25 × 7–10 cm up to 2.2 cm thick at the base, flabelliform, upper surface brownish orange (6C8), orange-rooted to reddish brown (8D8) at maturity, weakly to strongly laccate, reniform, dimidiate, pilei expanding, sometimes with pilei growing from the lower pilei or growing together, up to 36 cm, and 54 cm in overall width from the lower pilei, curly and wavy edges; lower surface yellowish white (4A2) to brownish gray at maturity. The young basidiocarp’s upper surface brownish orange (6C8), orange-rooted to reddish brown (8D8), somewhat lacquered, obviously sulcate, rugged and non-rough, margin obtuse or not, white to orange-yellow. Context 0.1–1.8 cm thick, light brown (6D6) to dark brown (6F8), occasionally melanoid in KOH, corky. Hymenophore whitish cream on the surface while young, straw or light brown (6D6) at maturity. Pores, subcircular to circular, 25–110 µm thickness, 60–80 µm per mm, 60–220 µm in diameter, 3–5 spores/mm. Stipe 1.5–3.5 cm in length, up to 0.7–3.0 cm in width, sub-cylindrical to cylindrical, strong laccate, reddish brown (9D7), and brownish red (10D6) at maturity.
Hyphal structure
hyphae system trimetric, colored, generative hyphae; 2.0–5.2 µm in diameter (n = 30), colored, thin-walled; skeletal hyphae 4.3–7.1 µm broad (n = 30), yellowish brown to reddish brown in KOH; binding hyphae, 1.2–2.0 µm in diameter, few, wall thick, very ramified. Basidiospores ellipsoid, mostly truncated, double walls, brownish orange (7C4) to brown (7E5), (7.3)8.0–11.5(12.2) × (5.3)5.5–7.8(8.3) µm, ( with Qavg = 1.79 ± 0.28, Lm = 10.63 ± 0.7µm, Wm = 6.81 ± 0.54 µm (with myxosporium), (6.6)7.3–10.9(11.3) × (4.9)5.1–7.2(7.7) µm, ( with Qavg = 1.47 ± 0.34, Lm = 8.73 ± 0.63µm, Wm = 6.2 ± 0.35 µm (without myxosporium). Exosporium (outer wall), hyaline, light brown to brownish orange (6A4, 6C8), endosporium (inter-wall) with conspicuous echinulae, fine dark brown (7F) eursporium. Pileipellis cutis, consisting of clavate cells, 13–426.0–13.6 µm, dextrinoid to mildly or severely amyloid.