Pseudohydnum fusiforme Xin Zhang & Y. C. Dai

Pseudohydnum fusiforme Xin Zhang & Y. C. Dai, MycoKeys 131: 257 (2026) Fig. 4 Description. Basidiomata small-sized, gelatinous when fresh, pileate, subsessile to laterally stipitate, solitary or gregarious (sometimes confluent at the base). Pileus up to 35 mm in widest diameter and 6 mm thick, spathulate, flabellate, semicircular, to shell-shaped; pileal surface minutely velutinous to pubescent, initially white to watery-grayish, transitioning through clay-pink or pale brown, and ultimately becoming brown, translucent when fresh; margin sharp to slightly blunt, entire, sometimes undulating, fertile. Hymenophore hydnoid; spines sharp-tipped, 0.8–1.5 mm long, 3–5 per mm, white. Stipe 5–10 mm long, 4–8 mm in diam., lateral, grayish white to watery-grayish, subequal, subcylindrical, translucent; surface often covered with fine spines, rudimentary in some specimens. Context gelatinous, translucent, unchanging. Odor and taste mild. Basidiospores [60 / 3 / 3] (6.5 –) 7.0–8.8 (– 9.5) × (6.5 –) 6.8–8.5 (– 9.5) μm, Q = 1.00–1.09 (– 1.11), Qm = 1.04 ± 0.03, globose to subglobose, hyaline, smooth, thin-walled, nonamyloid, with a small apiculus, frequently germinating by repetition or by germ tubes. Basidia 11–14 × 10–13 μm, longitudinally cruciate-septate, 4 - spored, arranged in a dense palisade extending to the spine apices; sterigmata up to 28 × 2–4 μm. Cystidia fusiform, 20–45 × 2–5 μm; Hyphidia 1–4 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, 2–8 μm in diam., slightly inflated, thin- or slightly thick-walled, hyaline to brownish. Contextual hyphae 1-7 μm in diam., frequently branched, interwoven, thin- to slightly thick-walled, hyaline. Subhymenial hyphae hyaline, thin-walled, interwoven or anastomosing, 2–6 μm in diam., occasionally inflated up to 14 μm. Ecology and distribution. Growing on decayed coniferous wood (Abies spp.). Currently known only from Xizang and Yunnan, southwestern China. Specimens examined. China • Xizang Autonomous Region, Motuo County (墨脱县), near the Guoguotang Great Bend of the Yarlung Tsangpo River (雅鲁藏布江果果糖大拐弯), 29°18'N, 095°18'E, elev. 3,275 m, 18 September 2014, leg. W. L. Lu, X. D. Hu & Y. J. Yao (HMAS 272859, HMAS 272825); • Yunnan Province, Deqin County (德钦县), near Baima Snow Mountain pass (白马雪山), 28°24'30"N, 098°59'13"E, elev. 3,780 m, on decaying Abies wood, 4 October 2025, leg. T. J. Yu (MHKMU YTJ 405, MHKMU YTJ 424; MHKMU YTJ 425, MHKMU YTJ 426). Comments. Pseudohydnum fusiforme was recently described from Xizang, southwestern China, where it grows on fallen trunks of Abies delavayi var. motuoensis at high elevations (> 3,200 m) (Zhang et al. 2026). Here, we report this species for the first time from Yunnan Province. Our specimens conform to the diagnostic features (fusiform cystidia) but also exhibit notable morphological discrepancies from the protologue, including subsessile to laterally stipitate basidiomata, denser spines (3–5 per mm vs. 2 per mm); slightly wider and more globose basidiospores (7.0–8.8 × 6.8–8.5 μm vs. 7.0–8.5 × 5.5–7.0 μm), and a previously undocumented ontogenetic color change, progressing from white to watery-grayish, clay-pink, and ultimately brown. These findings expand both the known geographic range and the morphological circumscription of the species, suggesting that observed differences likely reflect intraspecific morphological variation. Both P. fusiforme and P. incarnatum occur in Xizang on Abies and share fusiform cystidia, but they differ significantly in morphology. Macroscopically, P. incarnatum has a smaller, pink pileus (up to 23 mm vs. 35 mm wide) and sparser spines (2–3 vs. 3–5 per mm). Microscopically, P. incarnatum has wider cystidia (18.5–36.0 × 6.5–10.2 μm vs. 20–45 × 2–5 μm) and slightly narrower and more elongate basidiospores (6.0–8.2 × 5.0–6.2 μm vs. 7.0–8.8 × 6.8–8.5 μm) (Guan et al. 2026).