Grifola sinensis S.M. Tang & S.H. Li sp. nov.

Figs 6, 7, 8, 10C, D

Etymology.

The epithet “sinensis” refers to the country China where this fungus was first discovered.

Holotype.

China. Yunnan province: Nujiang prefecture, Fugong city, elev. 2,230 m, 8 September 2019, Shu-Hong Li, L5453 (holotype: HKAS 131995!).

Diagnosis.

Differs from other Grifola species in having a medium-sized basidiomata, with white to olive yellow lobes, smaller and irregular pore (2-4/mm), and ellipsoid to narrowly utriform chlamydospores.

Description.

Basidiomata medium-sized, developing a fruiting structure composed of multiple flattened lobes that emanate from a central base, up to 10 × 12 × 15 cm. Lobes 4-7 cm wide, 7-10 cm long, lower and upper surface white (1A1) to grayish white (1A2) when young, changing to olive yellow (2C-D7) with age or when soaked. Thin cuticle. Context white, 1-2 mm thick. Pores often with a convoluted, maze-like appearance, 2-4 per mm, tubes 2-3 mm deep. Texture fleshy to cartilaginous, becoming hard and woody upon drying, and emitting a pronounced almond scent when fresh or dry.

Skeletal hyphae aligned parallel longitudinal alone lobe, with repent and abundant suberect terminal segments, hyphae thin-walled, non-staining in IKI and 5% NaOH solution, 5-7 μm wide. Pores edge heteromorphous, hyphae thin-walled, colorless in 5% NaOH solution, 2-4 μm wide; trama of tubes regular, parallel, 120-190 μm wide, made up of thin-walled hyphae, 2-5 μm wide.

Basidia 15-28 (-32) × 5-8 μm, av. 23.0 ± 5.4 × 6.7 ± 0.7 μm, clavate, thin-walled, mostly 2-spored, rarely 4-spored; sterigmata 2-5 μm long. Basidiospores [68/2/2] 4.6-7.9 × 3.0-5.9 μm, av. 5.9 ± 0.6 × 4.2 ± 0.5 μm, Q = 1.1-1.6 (-1.8), Qm = 1.42 ± 0.15, broadly ellipsoid to ellipsoid, colorless in IKI and 5% NaOH solution, thin-walled, irregular ornamented (Fig. 10); basidiospores scatter plot, see Fig. 9.

Culture feature (Fig. 8). Colony regular, circular, greenish gray (1B2) to grayish yellow (1B3); reverse pale yellow (1A3). Dimitic hyphal system, generative hyphae rarely branched. Texture sub felty and farinaceous. Growth slow, 4 cm in 3 weeks on Potato Dextrose Agar with Chloramphenicol and 24 °C. Mycelium with no distinctive odor, generative hyphae clamped, thin-walled, and colorless in 5% NaOH solution, 3-5 μm wide. Presence of chlamydospores terminal or intercalary, mostly ellipsoid, rarely narrowly utriform, 9.6-16.1 (-21.9) × 7.4-11.9 μm, av. 13.4 ± 2.9 × 9.2 ± 1.2 μm, Q = 1.1-2.0 (-2.9), Qm = 1.5 ± 0.5, colorless in 5% NaOH solution, thin-walled. Generative hyphae hyaline, thin walled, clamped, 2.7-4.3 μm, av 3.6 ± 0.6 μm, hyphal endings arranged singly or in groups, with contents stained red in Congo solution.

Habitat and distribution.

Grifola sinensis occurs in native forests in Yunnan, on Lithocarpus corneus, at the base of trees, causing an aromatic white rot.

Edibility.

This species is much appreciated by the locals in Yunnan, stir-frying it over high heat with green peppers; it has a robust almond essence that permeates through the palate, accompanied by a hearty, meat-like texture.

Additional species examined.

China. Yunnan Province, Nujiang prefecture, Fugong city, elev. 2,120 m, 5 September 2019, Shu-Hong Li, HKAS 131998; Nujiang prefecture, Bingzhongluo county, elev. 1,980 m 15 October 2023, Song-Ming Tang, HKAS 131994.

Notes.

Morphologically, G. sinensis is similar to G. amazonica Ryvarden in having small irregular pores 2-4/mm. However, G. amazonica has evenly brown lobes, smaller basidiospores 4-4.5 × 3-3.5 μm, and basidia 12-14 × 3.5-4.5 μm, grows on dead hardwood trees, and its distribution is in the North Hemisphere (Ryvarden 2004).

Grifola gargal Singer is close to G. sinensis, both having cream yellow pilei, and pores 1-2/mm. However, G. gargal has larger basidiospores, 7-8 × 5-6 μm, and monomitic hyphal system (Singer 1969; Rugolo et al. 2023).

In our multi-locus phylogeny, G. sinensis is closely related to G. frondosa and G. edulis . However, G. frondosa has dark to pale gray pilei, larger basidiomata, up to 40-50 cm, and white pores. Grifola edulis has irregular, mostly tibiiform or narrowly clavate, rarely narrowly lageniform or ellipsoid and relatively larger chlamydospores, (13-) 22-94 (-115) × 7-12 μm, av. 49.8 ± 28.5 × 9.4 ± 1.4 μm, gray to gray-brown pilei and cuticle hyphae terminal segments slightly enlarged (this study).