Pseudohydnum ellipsosporum T. J. Yu & L. P. Tang 2026, sp. nov.

Pseudohydnum ellipsosporum T. J. Yu & L. P. Tang sp. nov. Fig. 3 Chinese name. 椭圆孢刺银耳. Diagnosis. Similar to P. laricicola, but differs in its dark olive-brown pileus, compressed stipe, and longer and more elongate basidiospores (9.0–11.7 × 5.5–7.0 μm). Holotype. China • Yunnan Province, Ninglang County (宁蒗县), en route from Gewa Village (格瓦村) to Labo Town (拉伯乡), 27°43'23"N, 100°31'59"E, elev. 3,460 m, on decaying Picea wood, 2 October 2023, leg. T. J. Yu (holotype, MHKMU YTJ 198-1). Etymology. From Greek elleipsis (ellipse) and spora (spore), referring to the ellipsoid shape of the basidiospores, a key diagnostic feature of this species. Description. Basidiomata large-sized, gelatinous when fresh, pileate, laterally stipitate to rarely subsessile, solitary. Pileus up to 55 mm in widest diameter and 10 mm thick, semicircular to flabellate; pileal surface strigose to pubescent, dark olive-brown (4 E 8) to dark brown (6 E 6), translucent when fresh; margin sharp, entire, undulated, upturned, fertile. Hymenophore hydnoid; spines sharp-tipped, up to 2 mm long, 2–3 per mm, white (1 A 1). Stipe 5–40 mm long, 6–24 mm in diam., lateral, white (1 A 1) to watery-grayish (1 F 1), compressed, translucent; surface densely covered by short spines, rudimentary in some specimens. Context gelatinous, translucent, unchanging. Odor and taste not recorded. Basidiospores [60 / 3 / 2] (8.7 –) 9.0–11.7 (– 12.0) × (4.5 –) 5.5–7.0 (– 7.2) μm, Q = (1.36 –) 1.46–2.11 (– 2.27), Qm = 1.71 ± 0.18, ellipsoid to elongate, occasionally cylindrical, hyaline, smooth, thin-walled, nonamyloid, with a small apiculus, frequently germinating by repetition or by germ tubes. Basidia 12–17 × 10–16 μm, longitudinally cruciate-septate, 4 - spored, arranged in a dense palisade extending to the spine apices; sterigmata up to 17 × 2–4 μm. Hyphidia 1–3 μm in diam., common, branched, with simple septa or clamp connections. Hyphal system monomitic, generative hyphae with clamp connections. Pileipellis composed of subparallel or ascending hyphae, 1–7 μm in diam., occasionally branched and inflated up to 30 μm, thin- or slightly thick-walled, hyaline to brownish. Contextual hyphae 1-11 μm in diam., interwoven, thin- to slightly thick-walled, hyaline. Subhymenial hyphae hyaline, thin-walled, interwoven or anastomosing, 1–6 μm in diam., occasionally inflated up to 22 μm. Ecology and distribution. Growing on decayed conifer wood (Picea and Taxus spp.). Currently known only from Yunnan, southwestern China. Other specimens examined. China • Yunnan Province, Ninglang County (宁蒗县), en route from Gewa Village (格瓦村) to Labo Town (拉伯乡), 27°43'45"N, 100°32'02"E, elev. 3,260 m, on decaying Picea and Taxus wood, 30 September 2023, leg. T. J. Yu (paratype, MHKMU YTJ 152); • ibid., 27°43'23"N, 100°31'59"E, elev. 3,460 m, on decaying Picea wood, 2 October 2023, leg. T. J. Yu (MHKMU YTJ 198-2, MHKMU YTJ 198-3). Comments. Pseudohydnum ellipsosporum is distinguished by its large-sized, stipitate to subsessile basidiomata (pileus up to 55 mm in widest diameter), dark olive-brown pileus, and ellipsoid to elongate basidiospores (9.0–11.7 × 5.5–7.0 μm). Morphologically, it resembles P. brunneovelutinum C. C. Nascim. & Menolli and P. meridianum, but differs in basidiome size, stipe development, spine density, and spore dimensions. Pseudohydnum brunneovelutinum differs in its flabelliform to petaloid basidiomata with a short to rudimentary stipe, a smaller pileus (up to 35 mm in widest diameter), strongly and irregularly branched hyphidia, and its occurrence in tropical South America on angiosperm wood (Coelho-Nascimento et al. 2024). Pseudohydnum meridianum differs in its denser and shorter spines (0.5–1 mm long, 3–4 per mm), and smaller, subglobose to globose basidiospores (5.1–6.2 × 4.9–5.8 μm), and its occurrence on decayed wood in lowland evergreen mixed forest (Spirin et al. 2023; Wang et al. 2025). Phylogenetically, P. ellipsosporum was recovered as sister to the temperate P. sinobisporum from Northeast China. However, the latter is readily distinguished by its smaller ivory pileus (up to 12 mm), shorter and more rounded basidiospores (7.5-9.5 × 5.8-7.2 μm), and predominantly 2 - spored basidia (Zhou et al. 2023).