Cystoderma alticola R.L. Zhao, B. Cao & J.Xin Li, in Cao et al., Fungal Diversity 132: 557 (2025)
Index Fungorum number: IF 572413; MycoBank number: MB 572413; Facesoffungi number: FoF 17670; Figs. 1, 2
Etymology – alticola (Latin), made up of “altus” (high) and “cola” (dweller, inhabitant), referring to the habitat of this species in high-altitude regions of Xizang Autonomous Region, China, where all specimens were collected at elevations above 3800 m.
Holotype – HMAS 288001.
Pileus 12–30 mm in diameter, initially hemispherical to paraboloid with obtuse umbo, gradually becoming convex to plano-convex with age, surface dry, yellowish-ochre to pale yellow, darker toward the disc, covered with granulose scales or fine powdery texture, slightly wrinkled, an incurved margin at first, then applanate with age, the margin often separates from the partial veil, yellowish-ochre and yellowish-white. Lamellae adnate, white to pale cream, crowded, with 2–3 lamellulae of different lengths, 1–3 mm broad, ventricose. Stipe 25–60 × 2.5–5.5 mm, cylindrical, yellowish, yellowish-brown, or brownish, with an evanescent floccose-scaly ring zone, persistent, yellowish brown and silky striate above the ring zone, below the ring zone yellowish-ochre to pale yellow, attached with numerous small granular furfuraceous squamules. Odor and taste are undocumented.
Basidiospores (4.1–)5.1–6.0(–6.9) × (2.8–)3.1–3.7(–4.2) µm (x̄ = 5.5 ± 0.5 × 3.4 ± 0.3, Q = 1.5–1.8, Qm = 1.6 ± 0.2, n = 60), ellipsoid both in side view and front view, smooth, hyaline, thin-walled, without a germ pore, inamyloid. Basidia 22.1–31.0 × 6.0–7.6 µm, clavate, smooth, hyaline and thin-walled, 4-spored. Pleurocystidia and cheilocystidia absent. Pileipellis on the upper layers composed of chains of numerous sphaerocytes, globose to subglobose, ellipsoid, thick-walled, the lower layers composed of tightly interwoven hyphae, with internal brown pigment. The composition of the evanescent floccose-scaly ring zone and pileipellis is identical. Clamp connections present in all tissues.
Habitat – Solitary, scattered, sometimes gregarious. Saprobic on mixed coniferous-broadleaf forest, found at elevations above 3,000 m, approaching 4,000 m in highland regions.
Materials examined – CHINA, Xizang Autonomous Region, Bomi to Motuo, 24 July 2021, Mao-Qiang He & Zhi-Lin Ling, ZRL20210848 (HMAS 288001, holotype) and ZRL20210866 (HMAS 288002); Linzhi City, Forest Ecology Monitoring Station, 27 July 2021, Mao-Qiang He & Zhi- Lin Ling, ZRL20211049 (HMAS 288003); Shigatse City, Yadong County, Lower Sima Township, 14 September 2015, Xu-Ming Bai, ZRL20152147 (HMAS 288005).
GenBank – HMAS 288005: PV389788 (ITS), PV389796 (LSU); HMAS 288001: PV389789 (ITS), PV389797 (LSU); HMAS 288002: PV389790 (ITS), PV389798 (LSU); HMAS 288003: PV389791 (ITS), PV389799 (LSU).
Notes – Phylogenetic analyses based on ITS and nrLSU sequences indicate that Cystoderma alticola clusters with C. carcharias, C. granosum, and C. tuomikoskii, forming a well-supported lineage within Cystoderma (Fig. 1). Morphologically, C. carcharias can be distinguished by its white pileus and stipe, which exhibit a grayish-pink or vinaceous tinge (Saar 2003, 2012). Cystoderma granosum features basidiospores measuring 4.5–5.2 × 2.9–3.5 µm, which are shorter and narrower than those of C. alticola (Li et al. 2022a). Cystoderma tuomikoskii closely resembles C. alticola due to its brownish pileus and similar basidiospore dimensions. However, C. tuomikoskii has been reported from low-altitude regions (Saar 2003), whereas C. alticola occurs in the Xizang Autonomous Region at elevations above 3,000 m.
Figure 1 – Maximum Likelihood tree of Cystoderma inferred from ITS and nrLSU sequences data, rooted with Crucibulum leave. Branches supported by both BS = 70% and PP = 0.90 were labeled. The examined specimens in this study are bolded.
Figure 2 – Cystoderma alticola. a Basidiomata (HMAS 288001, holotype). b Basidiomata (HMAS 288002). c Basidiospores. d Basidia. Scale bars: a–b = 1 cm, c–d = 5 µm.