Gerhardtia yunnanensis M. MU & L.P. Tang, sp. nov. (Figs. 3–5).

MycoBank: MB 837965.

Etymology:—“yunnanensis” refers to the holotype locality Yunnan Province, southwestern China.

Diagnosis:—Characterized by its yellow-brown to reddish brown pileus translucent-striate at margin, subdistant to crowded lamellae, weakly curved stipe, basidia with cyanophilous and siderophilous granules, cyanophilic basidiospore walls with minute granules or verruculose ornamentation blue after staining in Cotton Blue, narrowly clavate to irregular or curved clavate cheilocystidia and pleurocystidia.

Holotype:— CHINA. Yunnan province: Shizong County, Junzi Mountain, 24°39′14″N, 104°9′58″E, elev. 2268 m, 7 th August 2019, L. P. Tang 2686 (MHKMU-Tang 2686).

Gene sequences ex-holotype: MT514924 (ITS); MT514921 (LSU).

Description:— Basidiomata medium to large. Pileus 8–16 cm in diam, slightly hemispherical to convex at first, expanding to plano-convex or applanate, slightly depressed over disc, sometimes slightly broadly umbonate or umbilicate at the center when mature; expanding to inflexed or uplifted when mature, sometimes flexuous, mostly yellow-brown (5C4–6) to reddish brown or grayish red (7C4–5) over disc, dark red (7D5–6), brown to dark brown (6E8) at the center, becoming grayish orange (6B2–5) to whitish (6B1) towards margin; surface smooth or glabrous, margin with faint to obvious striae. Lamellae white to orange-white (5A1–2), adnate to slightly sinuate; 3–6 lamellulae between two complete lamellae; subdistant to crowded when mature, about 36–46 complete lamellae/cap. Stipe 5.5–8 cm long, 0.8–2 cm diam, white to orange-white (5A1–2); subcylindrical or tapering towards base, often weakly curved; occasionally hollow in center. Context white to yellowish white (5A1–2), fleshy in the pileus, fleshy-fibrous in the stipe. Odor and taste not distinctive.

Basidiospores [80/14/6] (–4.8)5.0–6.0(–6.24) × (–2)2.5–3.0(3.2) µm, Q = 1.67–2.08, Q m = 1.79 ± 0.10, short cylindrical or oblong, thin-walled, walls cyanophilous, inamyloid, hyaline, with very minute dots or verrucae under the light microscope after staining in Cotton Blue, slightly undulate and with minute granules or verruculose ornamentation under SEM; apiculus small about 0.5 μm long (Fig. 5a, 5d). Basidia 28–36 × 5–7 µm, narrowly clavate or cylindrical, thin-walled, smooth, hyaline, with cyanophilous and siderophilous granulations, 4-sterigmate up to 3–5 µm long (Fig. 5b, 5c). Cheilocystidia and Pleurocystidia present but not projecting beyond other hymenial elements, narrowly clavate to irregular or curved clavate, 16–35 × 2.5–3.5 µm (Fig. 4a, 4b). Hymenophoral trama composed of regular or somewhat parallel, hyphae 4–9 µm wide, thin-walled, smooth, hyaline (Fig. 4e). Pileipellis a cutis, hyphae 5–9 μm wide, loosely interwoven, thin-walled, smooth, hyaline (Fig. 4c). Stipitipellis consisting of parallel hyphae 4–7 µm wide, thin-walled, smooth, hyaline (Fig. 4d). Clamp connections absent in all tissues.

Substrate and habitat:—Scattered on the soil in broad-leaved forests or coniferous and broad-leaved mixed forests dominated by Pinus yunnanensis, Lithocarpus dealbatus (Hook.f. & Thomson ex Miq.) Rehder, Q. fabri, Rhododendron sp. and Docynia delavayi (Franch) Schneid, elev. 2268–2350 m, July–September.

Other specimens examined:— CHINA. Yunnan Province: Shizong County, Junzi Mountain, 24°37′59″N, 104°9′53″E, elev. 2350 m, 24 th July 2020, H. Y. Huang 609 (MHKMU-Huang 609) [GenBank Acc. No.: MW 040071 (ITS); MW 040072 (LSU)]; the same location, 24°38′21″N, 104°9′6″E, elev. 2275 m, 10 th August 2019, T. Huang 50 (MHKMU-HT 50) [GenBank Acc. No.: MT 514922 (ITS); MT 514918 (LSU)]; the same location, 24°39′33″N, 104°10′31″E, elev. 2272 m, 7 th August 2019, Y. J. Pu 26 (MHKMU-Pu 26) [GenBank Acc. No.: MT 514925 (ITS); MT 514920 (LSU)]; the same location, 24°38′39″N, 104°9′12″E, elev. 2304 m, 8 th August 2018, L. P. Tang 2542 (MHKMU-Tang 2542) [GenBank Acc. No.: MT 514923 (ITS); MT 514919 (LSU)]; Wuding County, Gaoqiao Town, 25°39′15″N, 102°6′6″E, elev. 2272 m, 21 st August 2016, S. D. Yang 412 (MHKMU-Yang 412) [GenBank Acc. No.: MT 584660 (ITS); MT 584662 (LSU)].

Known distribution:—Known from Yunnan province in southwestern China.