Hydnum luteoalbum YonglanTuo, Bo Zhang & Yu Li sp. nov. Fig. 6 A – F Etymology. The specific epithet “luteoalbum” refers to the yellowish-white color of the entire basidiocarp. Holotype. China • Anhui Province, Lu’an City, Tianma National Nature Reserve, 31°15'43"N, 115°41'41"E, Elevation: ca. 1207 m. on soil in Quercus serrata Thunb. forest, 4 August 2023, Yonglan Tuo FJAU 66564. GenBank accession numbers: ITS: PV 329847, tef 1-α: PP 357254. Diagnosis. H. luteoalbum differs from other species of Hydnum by its ensiform-dagger spines, white pileus, and smaller basidiospores (7.0–7.5 × 6.0–6.5 μm). Description. Basidiocarps small to medium, solitary, 25.0–30.0 mm in height. Pileus 25.0– 60.5 mm wide, white to yellowish white (4 A 1–4 A 2), round to irregular, shallowly depressed in the center, discoloration not observed; margin incurved, azonate, white (4 A 1) tomentum; pileus context 2.0– 4.5 mm thick. Hymenophore hydnoid, spines non-decurrent, ensiform, slightly sparse, 1–2 spines / mm 2, white to yellowish white (4 A 1–4 A 2), 5.0–10.0 mm long, 0.5–1.5 mm diameter. Stipe 20.0–35.0 × 7.0–15.0 mm, central to slightly eccentric, solid, surface covered with white (4 A 1) tomentum. Odor mild or fruity. Basidiospores (6.0) 7.0–7.5 (8.0) × (5.5) 6.0–6.5 (7.0) μm, av. L = 7.08 μm, av. W = 6.10 μm, Q = (1.00) 1.08–1.17 (1.33), av. Q = 1.16, broadly ellipsoid, thin-walled, smooth, hyaline in 3 % KOH, some with granular contents, inamyloid, hilar appendix 0.5–1.0 μm long. Basidia (35.0) 36.0–50.0 (55.0) × (7.0) 8.0–10.0 (11.0) μm, clavate to suburniform, some with granular contents, sterigmata 2–4, 4.0–6.5 × 1.0–2.0 µm, conical, thin-walled, smooth. Basidioles (25.0) 30.0–40.0 (50) × (6.0) 7.0–10.0 (11.0) μm, smaller than basidia, some with granular contents. Subhymenium trama filamentous, hyphae 4.0–5.0 μm wide, thin-walled, hyaline in 3 % KOH. Hyphae of spines 7.0–8.0 μm, thin-walled, apex cylindrical. Pileipellis composed of cylindrical hyphae, slightly interwoven, terminal elements cylindrical at apex, cells 60.0–125.0 × 7.0–11.0 μm. Stipitipellis composed of cylindrical hyphae, slightly interwoven, 6.0–14.0 μm wide, terminal elements dilated at apex. Clamp connections present. Habitat and distribution. The species occurs solitarily in a Q. serrata forest within the core zone of Tianma National Nature Reserve, China (ca. 1100–1300 m, subtropical monsoon climate), with minimal human disturbance. Specimens were collected at a distance of 42.5 cm from a Q. serrata tree, with a diameter at breast height (DBH: 18.14 cm). Soil temperature was 22.5 ° C, soil volumetric water content was 20.5 %, soil pH was 5.8, air temperature was 24.2 ° C, and relative humidity was 90.1 %. Soil temperature, moisture content, and pH were measured at the time of sample collection; air temperature and humidity were monitored over the long term within the sample plot (measurements were taken at 10 - minute intervals; these data are mean values calculated over the 3 days preceding and following sample collection). Additional specimens examined. China • Anhui Province, Lu’an City, Tianma National Nature Reserve, 31°15'40"N, 115°41'46"E, Elevation: ca. 1193 m. on soil in Q. serrata Thunb. forest, 4 August 2023, Yonglan Tuo FJAU 66565. GenBank accession numbers: ITS = PV 329848, tef 1-α = PP 357255. Notes. Morphologically, H. luteoalbum has medium-sized basidiocarps and is similar to H. flavidocanum in pileus and stipe color, but it has smaller basidiospores (7.08 × 6.10 μm vs. 9.81 × 9.03 μm) and smaller basidia (36.0–44.0 × 8.0–10.0 μm vs. 45.0–82.0 × 10.0–14.0 μm). Phylogenetic analysis indicates that H. luteoalbum forms a distinct lineage and forms a sister branch to H. albotomentosum. Based on the above morphological characters and phylogenetic results, H. luteoalbum is easily distinguishable from other species of Hydnum and should be classified in subgenus Pallida.

Published as part of Tuo, Yonglan, Chu, Hang, Wang, Libo, Qi, Zhengxiang, Hu, Jiajun, Zhang, Bo, Li, Yu & Li, Xiao, 2026, Three new species and two new records of Hydnum (Hydnaceae, Cantharellales) from the Dabie Mountains, China, pp. 167-195 in MycoKeys 128 on pages 167-195, DOI: 10.3897/mycokeys.128.168361