红石囊小伞

3.2.2 Cystolepiota hongshiensis T. Bau and X. Y. Zhou, sp. nov.
MycoBank number: MB 851390 (Figures 5, 6).
Diagnosis: C. hongshiensis is distinguished from other Cystolepiota species by its hemispherical to convex pileus, with granulose to warty squamules, white to cream, and rough basidiospores under SEM. Its ITS, LSU, rpb2, and tef1-α sequences are different from those of other species.
Etymology: The species epithet “hongshiensis” is derived from the name of the park where the material was collected.
Type: China, Jilin Province, Huadian City, Hongshi Township, Red Rock National Forest Park, August 27, 2023, coll. T. Bau and X. Wang (HMJAU68204), Holotype!
Description: Basidiomata small. Pileus 0.3–2.2 cm, hemispherical when young, hemispherical to convex with age, white to cream; with granulose to warty squamules, white to cream, yellowish white (4A2–A3), orange white (6A2–A3); occasionally pinkish orange (6A2–A3) on center, margin appendiculate with veil remnants when young, concolorous with pileus; pileus context white to cream. Lamellae free, white to cream, crowded, up to 0.3 cm broad, with 1–3 tiers of lamellulae. Stipe 2.1–5.3 × 0.1–0.2 cm, subcylindrical, slightly enlarged at base, surface white to cream on the upper portion, greyish orange (5B2–B3) to reddish brown (8E4–E8) at base, with age gradually turning to reddish brown (8E4–E8) towards the middle and lower portion, with pulverulent to granulose squamules, concolorous with pileus, fugacious; context reddish brown (8E4–E8) at stipe base. Annulus white, fugacious. Odor and taste not recorded (Figures 5A–C, 6A).
Basidiospores [120,4,4] (−3.7) 4.4–5.9 (−6.1) × 2.0–3.5 μm, Q = 1.53–2.30, Qv = 1.89, long ellipsoid, hyaline, thin-walled, smooth-walled under the LM, distinct warts visible under SEM, inamyloid, non-dextrinoid, metachromatic in cresyl blue, cyanophilous. Basidia 15–22 × 5–7 μm, clavate, 4(2)-spored. Lamellar trama regular. Pleurocystidia and cheilocystidia absent. Pileus and stipe covering an irregular epithelium composed of globose to subglobose elements, 10–43 μm in diam., usually 2–5 cells forming loosely arranged chains, hyphae 1–4 μm in diam., slightly thick-walled, Clamp connections present in all structures (Figures 5D–F, 6B–D).
Habitat: Solitary to scattered on dead branches and rotten leaves of mixed forest.
Distribution: Found only in Jilin Province, northwestern China.
Additional specimens examined: China, Jilin Province, Jiaohe City, Qianjin forest farm, August 25, 2022, coll. T. Bau and H. Cheng (HMJAU68205); Jiaohe City, Hongyegu, July 31, 2023, coll. T. Bau and S. Y. Li (HMJAU68216); Huadian City, Zhaodaji Mountain National Forest Park, August 21, 2023, coll. T. Bau and X. Wang (HMJAU68207); Huadian City, Red Rock National Forest Park, August 27, 2023, coll. T. Bau, M. L. and X. Y. Zhou (HMJAU68203, HMJAU68206); August 28, 2023, coll. T. Bau, H. Cheng and X. Y. Zhou (HMJAU68202, HMJAU68212, HMJAU68215).
Notes: Macromorphologically, Cystolepiota hongshiensis and C. pseudoseminuda, with similar pileus surface squamules. But the latter pileus is plano-convex or applanate slightly umbonate, basidiospores (−3) 3.5–4.5 (−5) × 2–3 (−3.5) μm, Q = (−1.21) 1.24–1.85 (−2.20), Qm = 1.55 ± 0.19, ovoid to ellipsoid, the basidiospores of C. hongshiensis are more elongated than those of C. pseudoseminuda (Qu et al., 2023). In addition, there are 65 (out of 706) nucleotide differences between the ITS sequences of the holotype of C. hongshiensis and that of the holotype of C. pseudoseminuda.