Cystoderma yadongense R.L. Zhao, B. Cao & J.Xin Li, in Cao et al., Fungal Diversity 132: 562 (2025)
Index Fungorum number: IF 571629; MycoBank number: MB 571629; Facesoffungi number: FoF 17129; Figs. 111, 115
Etymology – yadongense (Latin), refers to the distribution where the type specimen was collected, Yadong County, Shigatse City, Xizang Autonomous Region in China.
Holotype – HMAS 287489.
Diagnosis – Cystoderma yadongense is characterized by a yellowish-ochre, granulose pileus with radial wrinkles, whitish lamellae, yellowish-brown stipe with evanescent ring zone, ellipsoid, smooth, weakly amyloid, small basidiospores. Gregarious under coniferous trees, surrounded by herbs, at high altitudes over 3000 m.
Pileus 20–45 mm in diameter, initially convex to plano-convex, eventually expanding to applanate; surface dry, yellowish-ochre, slightly granulose when young but becoming less apparent with maturity; developing radial wrinkles from the center towards the margin, less prominent when mature. Sometimes appendiculate with remnants of a partial veil, but not conspicuous. Lamellae adnexed or adnate, often with 1–2 lamellulae, approximately 3 mm broad, whitish, subdistant, occasionally ventricose in the middle. Stipe 37–64 × 3–6 mm, cylindrical, yellowish, yellowish-brown, or brownish, with an evanescent floccose-scaly ring zone; yellowish above the ring zone, brown to dark brown below the ring zone towards the base, attached with numerous small squamules similar to the ring zone. Context 1–3 mm broad, concolorous with the stipe; odor not distinctive.
Basidiospores (3.9–)4.1–5.0(–5.4) × (2.5–)2.7–3.2(–3.8) µm (x̄ = 4.6 ± 0.4 × 3.0 ± 0.2, Q = 1.4–1.7, Qm = 1.5 ± 0.1, n = 60), ellipsoid, smooth, hyaline, without a germ pore, weakly amyloid. Basidia 18.4–21.2 × 6.1–7.1 µm, clavate, smooth, hyaline, 4-spored. Pleurocystidia and cheilocystidia absent. Pileipellis composed of chains of numerous sphaerocytes, globose to subglobose, ellipsoid, slightly thick-walled, 12.9–25.4 µm, hyaline in KOH. Clamp connections present. Ring zone composed of hyaline hyphae, 3.2–10.8 µm in diameter, with attached sphaerocytes.
KOH reaction – strongly black on pileus of dry specimen.
Habitat – Gregarious on soil under coniferous trees, usually surrounded by herbaceous vegetation.
Known distribution – Southwest China.
Materials examined – CHINA, Xizang Autonomous Region, Shigatse City, Yadong County, Lower Yadong Town, 26 July 2022, Mao-Qiang He & Bin Cao, ZRL20220065 (HMAS 287489, holotype) and ZRL20220068 (HMAS 287490); 27 July 2022, Rui-Lin Zhao, ZRL20220248 (HMAS 287491).
GenBank – HMAS 287489: PP505410 (ITS), PP505413 (LSU); HMAS 287490: PP505411 (ITS), PP505414 (LSU); HMAS 287491: PP505412 (ITS), PP505415 (LSU).
Notes – Cystoderma yadongense can be distinguished by its yellowish-brown basidiomata with a slightly granulose surface and the presence of a well-developed but evanescent floccose-scaly ring zone. It produces relatively small basidiospores (4.1–5.3 × 2.6–3.1 µm). Phylogenetic analyses using ITS and nrLSU sequences indicated that C. yadongense clustered with C. amianthinum, C. pseudoamianthinum, C. rugosolateritium, and C. andinum, forming a well-supported lineage in Cystoderma (BS = 95, PP = 1). Morphologically, C. rugosolateritium and C. andinum can be differentiate by producing brick-colored Basidiomata with strongly radially wrinkled pilei in the field (Saar and Laessoe 2006; Li et al. 2022a). While C. yadongense, C. amianthinum, and C. pseudoamianthinum are similar in having pale yellow to yellowish-brown pilei and evanescent floccose-scaly ring zones (Li et al. 2022a), C. yadongense produces smaller basidiospores (4.1–5.3 × 2.6–3.1 µm) compared to the larger ones in C. amianthinum (4.0–)5.0–6.0(–7.0) × (2.5–)3.0–3.5(–4.0) µm and C. pseudoamianthinum (5–6.6 × 3–3.9 µm) (Li et al. 2022a). Morphologically, C. subglobisporum and C. granosum also form yellowish buff to pale-yellow pilei; however, both species develop a persistent membranous ring. Additionally, the basidiospores of C. subglobisporum are smaller (3.6–4.3 × 3.2–3.7 µm) (Li et al. 2022a).
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 yadongense (HMAS 287489, holotype). a Basidiomata in field. b Basidiospore. c Basidia. Scale bars: a = 1 cm, b, c = 5 µm.