Phaeocollybia lulangensis R. Y. Li & S. M. Tang 2026, sp. nov.

Phaeocollybia lulangensis R. Y. Li & S. M. Tang sp. nov. Figs 2 D, 3 C, 3 D, 5 Chinese name. 鲁朗暗金钱菌 (Lu Lang An Jin Qian Jun). Etymology. The epithet “lulangensis” refers to Lulang Town, Linzhi City, Xizang Autonomous Region, China, where the type specimen was collected. Holotype. China • Xizang Autonomous Region, Linzhi City, Lulang Town, elev. 3,419 m, 18 July 2025, Rui-Yu Li, (HKAS 154127!). Diagnosis. Phaeocollybia lulangensis is distinguished by a pure orange to strong orange pileus with an oily-subwaxy luster, a hollow stipe with a root-like pseudorhiza, limoniform basidiospores (5.3–6.3 × 3.8–4.6 μm) with a distinct suprahilar depression, and the absence of pleurocystidia. Clamp connections rare. Description. Pileus 2.5–4.0 cm diam, broadly conical to conical with subumbonate in center, margin inflexed and even edge, often wavy, surface smooth, mostly pure orange (# fda 200), deepening to strong orange (# c 16728) at the center and toward the margin, with an oily, subwaxy luster, pileus context thick, 0.1–0.3 cm wide, pale yellow (# fffa 9 e). Lamellae arcuate, adnexed, moderately close together, edge even or entire, 3–4 irregularly arranged tiers, 1–2 mm wide, vivid orange (# ffa 627). Stipe central, cylindrical, hollow, 5–8 cm long, including pseudorhiza, 0.8–1.0 cm diam, smooth in surface, subwaxy luster, pure orange (# f 69900), darkening toward the base. Pseudorhiza is 1–2 cm long, root-like, somewhat hollow in the upper part, with a base that tapers abruptly and becomes solid. Basidiospores [84 / 2 / 2] 5.3–6.3 × 3.8–4.6 μm, (N = 84, Q = 1.09–1.67, Q m = 1.40 ± 0.12, av. 5.83 ± 0.49 × 4.17 ± 0.36 μm, in face view limoniform with an apical papilla; in lateral view with a profile dominated by a suprahilar depression, rarely verruculose on the smooth; brown-toned in 1 % Congo Red and 5 % KOH solution. Basidia 19–33 × 6–9 μm (N = 20), av. 26.0 ± 3.7 × 7.5 ± 0.7 μm, mostly 4 - spored, rarely 2 - spored, sterigmata 3.2–4.9 μm long, sometimes with basal clamp connections, cylindrical to clavate, guttulate. Cheilocystidia 12–25 × 2–5 μm (N = 20), av. 27.2 ± 5.7 × 4.3 ± 0.6 μm, intermixed with basidia, narowly cylindrical, lageniform or flexuose, most have a long, rostrate apex, occasionally septate. Pleurocystidia not observed. Subhymenium thin-walled, 5–8 μm thick, with 2–3 layers of ovoid, fusiform or globose, and 1.8–5.1 × 1.1–6.6 μm, av. 3.1 ± 0.8 × 3.3 ± 1.2 μm. Hymenophoral trama regular, 45–105 μm wide, consisting of thin and hyaline hyphae, narrowly cylindrical hyphal elements, 25–40 × 4–8 μm wide. Pileipellis 90–150 μm thick, with a superficial layer of parallel, repent hyphae overlying an intricate trichoderm; the hyphae are slender, loosely arranged, 1.5–2.5 μm wide. Stipitipellis parallel aligned, thin-walled, hyphae 4–12 µm wide, sometimes constricted at the septal areas. Tibiiform diverticula abundant on pseudorrhizal pellis, 3–14 × 1–3 μm (N = 20), av. 5.8 ± 2.8 × 1.3 ± 0.4 μm, flexuose, narrowly cylindrical to narrowly conical with subcapitate apex, transparent and colorless, thin-walled. Clamp connections absent in all tissues examined. Habitat. Solitary or scattered in broad-leaved forests. Additional specimens examined. China • Xizang Autonomous Region, Mi Lin City, elev. 3,074 m, 18 July 2025, Song-Ming Tang, (HKAS 154128), paratype. Notes. Phaeocollybia lulangensis is morphologically similar to P. chefensis Norvell & Exeter, particularly in having a broadly conical pileus with a subumbonate center and overall orange coloration. However, P. chefensis is currently known from the Oregon coast and Coast Range in the USA; the two species can be distinguished by the following characters: the pileus of P. chefensis exhibits a distinctive uniform copper metallic sheen when dry, has larger basidiospores (av. 8.9 × 5.6 μm vs. 5.8 × 4.2 μm) that are consistently verruculose to verrucose, and has tibiiform cheilocystidia with thick-walled, refractive necks and capitula (Norvell et al. 2022). In the phylogenetic tree (Fig. 1), P. lulangensis forms a sister clade to P. ratticauda E. Horak. However, P. ratticauda is known from New Zealand and has a dry, reddish-brown to yellowish-brown pileus, pale violet lamellae, and heavily verrucose basidiospores, while the spore surface of P. lulangensis is smooth to rarely verruculose (Horak 1977). The ITS sequence difference between P. lulangensis (HKAS 154127, holotype) and P. ratticauda (PDD 72544) was 6.14 % (34 / 553, including three gaps).