Hydnum flosculoides Y. H. Xu, Y. F. Sun & B. K. Cui 2026, sp. nov.

Hydnum flosculoides Y. H. Xu, Y. F. Sun & B. K. Cui sp. nov. Figs 2 a, b, 3 Etymology. Flosculus (Lat.), refers to the flower-like appearance of the species with undulate pileus. Type. CHINA. Yunnan Province, Mangshi, alt. ca. 1200 m; 31 Aug. 2023, Yunnan Shanshifu leg., on ground of forest mixed by bamboo, Quercus and Pinus, Cui 23128 (BJFC, holotype). Diagnosis. Characterized by its flower-like basidiomata with large and undulate pileus (up to 110 mm wide), orange hymenophore with decurrent spines. Description. Basidiomata solitary to gregarious, fleshy and moderately firm when fresh, becoming leathery upon drying. Pilei up to 110 mm wide, round to reniform, plano-convex when young; ellipsoid or irregularly round, umbilicate at center or infundibuliform when old. Pileus surface dry, subglabrous, azonate, pale orange to orange (5 A 3–6 B 8) when fresh, yellow-orange to grayish orange (4 B 8–5 B 4) when dry. Pileus margin thin, entire, undulate, strongly decurved, same color or sometimes darker than the pileus surface. Context 1–5 mm thick, white to cream white (4 A 2). Hymenophore hydnoid, spines decurrent, crowded, evenly distributed; surface orange-white (5 A 2) when fresh, light orange or brown (5 A 4 / 6 D 4) when dry; subulate, acute, straight to somewhat flexuous, solitary, 1–3.5 mm long, shortest near the pileus margin, 3–4 per mm, brittle when dry. Stipes central, 40–70 mm long, 16 mm wide, subcylindrical, solid; surface glabrous, white to cream white (4 A 2); stipe base enlarged and covered with a little amount of white basal mycelium. Odor mild and fruity. Basidiospores subglobose to broadly ellipsoid, hyaline, thin-walled, smooth, some with granular contents, IKI –, (5.4 –) 5.6–6.7 (– 6.9) × (4.7 –) 5–5.8 (– 6.4) μm, av. 6.14 ± 0.31 × 5.37 ± 0.30 μm, Q = 1.05–1.23 (n = 90 / 3), Qm = 1.14 ± 0.06. Under SEM, the basidiospores smooth without any ornamentation, each bearing a distinct hilar appendix at the attachment point. Basidia subcylindrical to clavate, 27–39 × 6.5–8.5 μm, sometimes containing granular contents; sterigmata 2–4, up to 4–8 μm long, 1–1.2 μm wide at base, slightly curving. Basidioles numerous, subcylindrical to subclavate, 25–36 × 6.5–7 μm. Cystidia absent. Hyphae of spines 2.3–3.7 µm wide, cylindrical, thin-walled, smooth, hyaline, subparallel, enlarged at hyphal apex or septum, up to 4.7–9.9 μm, greenish yellow in KOH. Pileipellis composed of loosely interwoven erect to cylindrical hyphae, occasionally containing granular contents, 4–7.5 µm wide, enlarged at hyphal apex to 6–11 μm. Stipitipellis composed of subcylindrical hyphae, thin-walled, interwoven, 3–3.6 μm wide, terminal elements rounded at apex, sometimes containing hyaline oily droplets. Clamp connections present in all tissues. Additional materials examined. CHINA. Yunnan Province, Chuxiong, Zixi Mount., alt. ca. 1500 m, 11 Aug. 2023, Bao-Kai Cui leg., on ground of forest mixed by Fagus and Pinus, Cui 22857 (BJFC). Yunnan Province, Mangshi, alt. ca. 1200 m, 31 Aug. 2023, Yunnan Shanshifu leg., on ground of forest mixed by bamboo, Quercus and Pinus, Cui 23129 (BJFC). Distribution. Known only from China. Notes. In the phylogenetic tree, Hydnum flosculoides was involved in subg. Hydnum forming a separate group (98 % ML bootstrap, 1.00 BPP; Fig. 1). It is closely related to H. sphaericum which both have a cream to orange pileus surface, crowded spines, thin-walled hyphae with clamps in the spines. However, H. sphaericum differed from H. flosculoides in having a subglobose and smaller pileus (25–35 mm), smaller stipes (18–25 × 5–8 mm, non-decurrent to subdecurrent spines in white, white (3 A 1–4 A 1) hymenophore when fresh and bigger basidiospores (8.0–8.8 × 6.5–7.5 μm; Cao et al. 2021).