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

Pseudohydnum roseolostipitatum T. J. Yu & L. P. Tang sp. nov. Fig. 7 Chinese name. 长柄粉盖刺银耳. Diagnosis. Similar to and phylogenetically close to P. himalayanum, but differs in its well-developed stipe often expanding at the base, pinkish gray to cinnamon brown pileus, slightly sparse spines (2–4 per mm), and globose to subglobose basidiospores and basidia. Holotype. China • Yunnan Province, Deqin County (德钦县), 28°24'36"N, 098°59'4"E, elev. 3,770 m, on decaying Abies wood, 3 October 2025, leg. T. J. Yu (holotype, MHKMU YTJ 393). Etymology. From Latin roseolus (pale pink) and stipitatus (stipe), referring to the pale pink pileus and well-developed stipe of this species. Description. Basidiomata medium-sized, gelatinous when fresh, pileate, laterally stipitate, solitary or gregarious (rarely confluent at the base). Pileus up to 45 mm in widest diameter and 3 mm thick, spathulate to flabellate or semicircular; pileal surface minutely velutinous to smooth, pinkish gray (7 B 3) to cinnamon brown (6 C 5, 6 D 6), translucent when fresh; margin sharp to slightly blunt, entire, undulating, fertile. Hymenophore hydnoid; spines sharp-tipped, 1–2 mm long, 2–4 per mm, white (1 A 1). Stipe 30–40 mm long, 10–17 mm in diam., lateral, watery-grayish (1 B 1) to pale brownish gray (3 B 2), clavate, typically tapering upward from a swollen, sometimes bulbous base, translucent; surface generally smooth, rarely bearing spines. Context gelatinous, translucent, unchanging. Odor and taste mild. Basidiospores [60 / 3 / 3] (6.7 –) 7.0–8.3 (– 8.5) × (6.3 –) 6.5–7.8 (– 8.3) μm, Q = (1.00 –) 1.01–1.13 (– 1.17), Qm = 1.05 ± 0.04, globose to subglobose, occasionally broadly ellipsoid, hyaline, smooth, thin-walled, nonamyloid, with a small apiculus, frequently germinating by repetition or by germ tubes. Basidia 10–15 × 9–15 μm, longitudinally cruciate-septate, 4 - spored, arranged in a dense palisade extending to the spine apices; sterigmata up to 15 × 2–4 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, 1–6 μm in diam., slightly inflated, thin- or slightly thick-walled, hyaline to brownish. Contextual hyphae 2-12 μm in diam., interwoven, thin- to slightly thick-walled, hyaline. Subhymenial hyphae hyaline, thin-walled, interwoven or anastomosing, 2–9 μm in diam., occasionally inflated up to 18 μm. Ecology and distribution. Growing on decayed coniferous wood (Abies spp.). Currently known only from Yunnan, southwestern China. Other specimens examined. China • Yunnan Province, Deqin County (德钦县), Yunling Town (云岭乡), 28°21'29"N, 098°49'50"E, elev. 3,800 m, 11 August 2016, leg. Y. Li (HMAS 277444); • ibid., near the Baima Snow Mountain pass, 28°24'20"N, 098°59'09"E, elev. 3,800 m, from decaying Abies wood, 4 October 2025, leg. X. J. Li (paratype, MHKMU LXJ 199). Comments. Pseudohydnum roseolostipitatum is distinguished by its medium-sized basidiomata, well-developed clavate stipe expanding at the base, pinkish gray to cinnamon brown pileus, and globose to subglobose basidiospores (7.0–8.3 × 6.5–7.8 μm). Among sympatric taxa, it differs from P. himalayanum (denser spines 5–6 per mm and broadly ellipsoid to subglobose basidiospores), P. incarnatum (short or sometimes rudimentary stipe, fusiform cystidia, and broadly ellipsoid to subglobose basidiospores) and P. laricicola (subcylindrical stipe lacking a bulbous base, more elongate basidiospores) (Zhou et al. 2022; Wang et al. 2025; Guan et al. 2026; this study). For non-overlapping species with pinkish to cinnamon-brown pigmentation, such as P. brasiliense C. C. Nascim., Zabin & Menolli, P. gelatinosum subsp. pusillum, and P. omnipavum, further distinctions are noted. Pseudohydnum brasiliense differs in its pubescent pileus, significantly shorter and thinner stipe (6–11 × 3.5–6 mm), and predominantly 2 - spored basidia (Coelho-Nascimento et al. 2024). Pseudohydnum gelatinosum subsp. pusillum is readily distinguished by its much shorter and thinner, or sometimes rudimentary, stipe (up to 5 mm long), which is typically covered with spines extending to the base (Spirin et al. 2023). Pseudohydnum omnipavum produces distinctly smaller basidiomata (up to 20 mm in diam.) with a much shorter and thinner stipe (up to 5 mm long). It is associated with Pseudotsuga and Tsuga (Spirin et al. 2023). Phylogenetically, P. roseolostipitatum shows a close affiliation with the Qinghai-Xizang Plateau clade containing P. himalayanum Y. C. Dai, F. Wu & H. M. Zhou but occupies an independent, strongly supported branch.