Resupinatus angulatus Q. X. Guan, H. Zhao, L. Zhuang, Yuan Yuan & Y. C. Dai sp. nov.

Figs 2 a, b, 3

Etymology.

Angulatus (Lat.): refers to the species having angular pores of hymenophore.

Holotype.

China • Jilin Province, Dunhua County, Yanminghu Forest Park, on fallen branch of Larix olgensis, collected by Yu-Cheng Dai, elev. 400 m, 43.641552°N, 128.527467°E, 13 September 2025, Dai 37973 (BJFC 059232).

Description.

Basidiomata annual, resupinate, gelatinous, without odor or taste when fresh, becoming fragile upon drying, up to 1.5 cm long, 1 cm wide, 120 µm thick at center. Hymenial surface poroid, bluish gray when fresh, turning to dark bluish gray upon drying. Pores angular, 3–4 per mm, Sterile margin indistinct and slightly cream; subiculum felty, loosely attached to the substrate and densely packed, up to 0.2 mm thick.

Hyphal system monomitic; generative hyphae with clamp connections, colorless, thin-walled, frequently branched, flexuous, interwoven, 1–3 µm in diameter; subicular hyphae thin- to thick-walled, branched, interwoven, 1.5–3 µm in diameter, IKI –, CB –; tissues unchanged in KOH. Cystidia absent; cystidioles fusiform, colorless, thin-walled, 10–15 × 3–5.5 µm. Basidia short clavate to pyriform, with four sterigmata and a basal clamp connection, with a few guttules, 17–22 × 5.5–7 µm; basidioles similar to basidia but slightly smaller. Basidiospores curved cylindrical to allantoid, colorless, thin-walled, smooth, IKI –, CB –, (5.4 –) 5.6–7.3 × 2.6–3.6 µm, L = 6.51 µm, W = 3.05 µm, and Q = 2–2.28 (n = 120 / 4).

Habitat and distribution.

It is known from Heilongjiang and Jilin, Northeastern China, growing on fallen branches of Larix olgensis and Pinus koraiensis.

Additional specimens examined (paratypes).

China • Jilin Province, Dunhua County, Yanminghu Forest Park, collected by Yu-Cheng Dai, elev. 400 m, 43.641552°N, 128.527467°E, 13 September 2025: on fallen branch of Pinus koraiensis, Dai 37947; on fallen branch of Larix olgensis, Dai 37958 (BJFC 059217), Dai 37970 (BJFC 059229), and Dai 37986 (BJFC 059245). • Heilongjiang Province: Tonghe County, Wulong National Park, on fallen branch of Larix olgensis, collected by Yu-Cheng Dai, elev. 29 m, 46.176944°N, 128.670833°E, 9 October 2025, Dai 38056 (BJFC 059315) and Dai 38061 (BJFC 059320); Fangzheng County, Longshan Forest Park, on fallen branch of Larix olgensis, collected by Yu-Cheng Dai, elev. 189 m, 45.822100°N, 129.394722°E, 11 October 2025, Dai 38209 (BJFC 059468); Linkou County, Yuanyangfeng Forest Park, on fallen branch of Larix olgensis, collected by Yu-Cheng Dai, elev. 318 m, 45.594848°N, 129.553944°E, 11 October 2025, Dai 38277 (BJFC 059536).

Notes.

Resupinatus angulatus is characterized by resupinate basidiomata; a poroid and bluish gray hymenial surface when fresh, dark bluish gray when drying; angular pores 3–4 per mm; a monomitic hyphal system bearing clamp connections; fusiform cystidioles; and curved cylindrical to allantoid basidiospores. Resupinatus angulatus is closely related to R. yunnanensis in the phylogeny (Fig. 1), but R. yunnanensis differs from R. angulatus by the absence of cystidioles and wider basidiospores (4.5–9 × 3.5–7 µm vs. 5.6–7.3 × 2.6–3.6 µm; Yang et al. 2023).