Aureonarius baimaensis X. Guo, Y. Fang & Y. L. Feng, 2025

Fang, Yuan, Feng, Yunli, Li, Jianying, Liu, Shaoxiong, Guo, Xiang, Zhou, Fan, Ma, Ming, Hua, Rong & Sun, Dafeng, 2025, A new species of Aureonarius (Cortinariaceae, Agaricales) from Southwestern China, Phytotaxa 706 (2), pp. 129-138 : 134-135

Aureonarius baimaensis X. Guo, Y. Fang & Y. L. Feng , sp. nov. Figs. 2 & 3 .

Fungal Names No. : FN572395.

Diagnosis: — Aureonarius baimaensis is mainly charaterized by medium-sized basidiomata; brownish-orange to reddish-brown tinge pileus and a pastel yellow tinge in the context; smooth central surface, with yellowish white to butter yellow finely fibrils near the edge; it typically has sterile lamella edges composed of smaller clavate cells.

Etymology: — baimaensis (Lat.) : refers to the type locality, Baimaxueshan National Nature Reserve, Diqing Zang Autonomous Prefecture.

Holotype: — CHINA, Yunnan Province, Diqing Zang Autonomous Prefecture, Deqin County, Quzonggong Baimaxueshan National Nature Reserve , elevation 3880 m, longitude and latitude 28°20′4″N, 99°2′51″E, 13 August 2024, KEF-13277 (GenBank No: ITS=PV124776; nrLSU=PV124777; RPB1=PV147138; RPB2=PV147140).

Description: — Basidiomata medium-sized. Pileus 4.0– 6.5 cm diam, hemispherical when young, later becoming convex to applanate, obtuse umbo at the centre, margin incurved or decurved to upturned; brownish orange (7C6-7) to reddish brown (8D7-8), darker at centre sometimes; central surface smooth, with luster when dry or viscid when wet, more yellowish white (3A2) to butter yellow (4A5) finely fibrils near the edge, with yellowish (5D4) to camel (6D4) universal veil remains at margin. Context up to 6 mm thick at pileus center, pale yellow (2A3) to pastel yellow (3A4). Lamellae adnexed to emarginate, 3–5 mm wide, close to moderately crowded, with irregular edge, pale yellow (2A3) when young, yellowish brown (5D5-5E7) to rust brown (6E7-8) when mature. Stipe cylindrical to clavate, bent, 5.5–9.0 cm long, 0.8–1.4 cm diam, pastel yellow (2A4) to light yellow (3A5), surface covered with universal veil when young, then longitudinally fibrillose above. Partial veil arachnoid, yellowish white (3A2-3) to butter yellow (4A5), then becoming yellowish brown (5D5-5E7). Universal veil distinct and persistent, fibrillose, covering whole basidiomata at first, then forming fibrils on pileus and stipe surface. Spore print rust brown (6E7-8). Chemical reaction with 5% KOH dark brown (8F4-6) on pileus and lamellae.

Basidiospores (6.5–)7.0–8.0(–8.6) × (4.5–)5.0–6.2(–7.1) μm, X av. =7.66 ± 0.54 × 5.94 ± 0.37 μm, Q = (1.10–)1.14– 1.38(–1.41), Q

av.

=1.29 ± 0.09, subglobose to broadly ellipsoid, yellowish brown, moderately to strongly verrucose,

inamyloid. Basidia (22.6–)28.1–35.5 × (6.8–)7.2–9.5 μm, 4-spored, sterigmata up to 3.2–4.5 μm, clavate, colourless or with amber yellow (4B6) oily inclusions or granules. Cystidia absent. Lamella edges heterogeneous, with sterile cells, 15.4–29.0 × 5.5–9.1 μm, clavate, subhyaline. Lamellar trama regular, composed of parallel arranged hyphae, hyphae 2.9–12.0 μm wide. Pileipellis an ixocutis, duplex, long-celled hyphae 2–15 μm wide, epicutis gelatinous, composed of amber yellow, irregularly arranged and strongly interwoven hyphae, hypocutis composed of colourless or amber yellow, nearly parallel cylindrical hyphae. Stipitipellis a cutis, gelatinous, stipe hyphae 5.0–8.0 μm wide, cylindrical, interwoven. Clamp connections present in stipe hyphae.

Habitat and distribution: —In duff and soil or among mosses in moist old-growth forests of Abies spp. and Quercus spp. Currently known from Yunnan Province, southwestern China.

Additional specimens examined (paratype): CHINA, Yunnan Province, Diqing Zang Autonomous Prefecture, Deqin County, Quzonggong Baimaxueshan National Nature Reserve ,in forest dominated by Abies georgei Orr. , elevation 3890 m, longitude and latitude 28°20′8″N, 99°2′39E, 13 August 2024, KEF-13360 (GenBank No: ITS=PV130372; nrLSU=PV124790; RPB1=PV147139; RPB2=PV147141) .

Figures

FIGURE 2. Basidiomata of Aureonarius baimaensis (holotype, KEF-13277) and Scanning electron micrographs (SEM) of basidiospores. Scale bars:A,B,C =1 cm; D = 5 μm.

FIGURE 3. Microscopic structures of Aureonarius baimaensis (holotype, KEF-13277). A: Basidiospores; B: Basidia and lamellar trama hyphae; C: Marginal cells; D: Pileipellis; E: Stipitipellis. Scale bars: 10 μm.