Polyporus sinosquamosus L. Zhuang, Y.C. Dai & K.Y. Luo, sp. nov. (Figs. 2–3)

MycoBank no.—MB 855792

Etymology: Sinosquamosus (Lat.) refers to the new species’ similarity to Polyporus squamosus and its discovery in China.

Type:— CHINA. Heilongjiang Province, Harbin, Laodong Park, on rotten angiosperm root, 27 July 2024, Dai 29814 (BJFC). Holotype DNA sequences: PQ306797 (ITS), PQ306794 (LSU).

Description:—Basidiomata annual, eccentrically stipitate, leathery, and without odor or taste when fresh, corky to slightly fragile when dry. Pilei flat with a depressed center, up to 12 cm in diameter and 4 mm thick at the center. Pileal surface buff-yellow to light brown when fresh, honey-yellow to grayish brown when dry, glabrous at margin squamosus at the center; margin sharp, incurved upon drying. Pore surface white to cream when fresh, honey-yellow to grayish brown when dry; pores angular, usually elongates or irregular, mostly 0.5–1 per mm, occasionally elongated to 2 mm long and 1 mm wide; dissepiments thin, entire to lacerate. Context white to cream when fresh, cream to light ivory when dry, corky upon drying, up to 2 mm thick. Tubes concolorous with pore surface, fragile, decurrent on the stipe, up to 2 mm long. Stipe brown to black, glabrous, up to 7 cm long and 2.5 cm in diam.

Hyphal structure—Hyphal system dimitic; generative hyphae bearing clamp connections; skeleto-binding hyphae IKI–, slightly CB+; tissues unchanged in KOH.

Context—Generative hyphae dominant, colorless, thin- to fairly thick-walled, rarely branched, 3–4 μm in diam; skeleto-binding hyphae colorless, thick-walled, moderately branched, interwoven, 3.5–4.5 μm in diam.

Tubes—Generative hyphae dominant, colorless, thin- to fairly thick-walled, rarely branched, 3–5 μm in diam; skeleto-binding hyphae, colorless, thick-walled, moderately branched, interwoven, 3.5–5 μm in diam. Cystidia and cystidioles absent. Basidia clavate, with a basal clamp connection and four sterigmata, 30–41 × 5.5–11 μm; basidioles in shape similar to basidia, but slightly smaller.

Stipe—Generative hyphae infrequent, colorless, fairly thick-walled, rarely branched, 2–3.5 μm in diam.; skeleto-binding hyphae dominant, colorless, thick-walled with a wide to narrow lumen, moderately branched, interwoven, 3–3.5 μm in diam.

Basidiospores cylindrical to oblong ellipsoid, hyaline, thin- to slightly thick-walled, smooth, some with one guttule, IKI–, CB–, (9.2–)10.6–14.1(–14.8) × (4.8–)4.9–6.9(–7.1) µm, L = 12.29 µm, W = 5.85 µm, Q = 2.08–2.12 (n=60/2) (the specimen Dai 26113b is sterile).

Additional specimens (paratypes) examined:— CHINA. Heilongjiang Province, Harbin, Maoershan Forest Park, on rotten angiosperm wood under grassland, 27 August 2023, Dai 26113b (BJFC); Songle Park, on rotten angiosperm root, 5 August 2024, Dai 29815 (BJFC).