MycoBank number: MB 851389 (Figures 3, 4).

Diagnosis: The identifying features of C. changbaishanensis are that the pileus is dirty white to cream, with pulverulent, granulose or subpyramidal squamules, cream, greyish orange, light brown, brown; pileus and pileus context becoming greyish orange to brown after drying; lamellae white to cream, turn grayish orange to light brown when drying; basidiospores obscure small warts visible under SEM; and cheilocystidia lageniform to broadly lageniform.

Etymology: The species epithet “changbaishanensis” is derived from the name of the mountain where the material was collected.

Type: China, Jilin Province, Jiaohe City, Qianjin forest farm, July 23, 2022, coll. T. Bau and H. B. Song (HMJAU68224), Holotype!

Description: Basidiomata small. Pileus 0.8–2.2 cm, hemispherical when young, expanding to plano-convex or applanate, slightly subumbonate with age, dirty white to cream; with pulverulent, granulose or subpyramidal squamules, dirty white to cream, greyish orange (6B2–B8), light brown (7D5–D8), brown (7E5–E8); pileus context whitish, pileus and pileus context becoming greyish orange (6B5–B7) to brown (7E6–E8) after drying. Lamellae free, white to cream, crowded, up to 0.4 cm broad, with 1–3 tiers of lamellulae, turning grayish orange (6B2–B8) to light brown (6D2–D8) when drying. Stipe 3.2–6.2 × 0.1–0.5 cm, subcylindrical, occasionally downward thickened; white to cream on the upper portion, subsmooth, with granulose squamules from the annular area downwards, concolorous with pileus, fragile and fugacious. Annulus white, fugacious. Odor and taste not recorded (Figures 3A–C, 4A).

Basidiospores [150,5,5] 4.6–6.0 (−6.4) × 2.1–3.0 (−3.4) μm, Q = 1.63–2.54, Q_v = 2.08, long ellipsoid to cylindrical, hyaline, slightly thick-walled, smooth-walled under the LM, small warts visible under SEM, inamyloid, non-dextrinoid, metachromatic in cresyl blue, cyanophilous. Basidia13–20 × 4–7 μm, clavate, 4-spored, sometimes 2-spored, greyish yellow (4C4–C6). Lamellar trama regular, greyish yellow (4C3–C7). Cheilocystidia 32–56 × 6–12 μm, lageniform to broadly lageniform, greyish yellow (4C4–C7) to golden yellow (1B4–B8), with a long cylindrical-tortuous apex, slightly thick-walled. Pleurocystidia absent. Pileus and stipe covering an irregular epithelium composed of globose, subglobose, spheropedunculate, 10–21 μm in diam., usually 2–5 cells in a string, brownish orange (5C2–C5). Clamp connections present in all structures (Figures 3D–F, 4B–E).

Habitat: Solitary, scattered or clustered on dead leaves and soil of mixed coniferous forests.

Distribution: Found only in Jilin Province, northwestern China.

Additional specimens examined: China, Jilin Province, Helong City, Xianfeng National Forest Park, August 22, 2021, coll. T. Bau and X. Wang (HMJAU68221); Jiaohe City, Qianjin forest farm, July 23, 2022, coll. T. Bau, L. Y. Zhu, W. N. Hou and H. B. Song, (HMJAU68228, HMJAU68229, HMJAU68230); Dunhua City, State forest farm, July 27, 2022, coll. T. Bau and W. N. Hou (HMJAU68225); Baishan City, Jingyu National White Bear Reserve, July 29, 2022, coll. T. Bau and L. Y. Zhu (HMJAU682310); Tonghua City, Baijifeng National Forest Park, July 8, 2023, coll. T. Bau, Q. R. Liu, Z. Q. Cheng, M. Liu and J. L. Wei (HMJAU68226, HMJAU68227, HMJAU68232, HMJAU68222, HMJAU68223).

Notes: Macromorphologically, this species is similar to C. fumosifolia, C. pyramidalis and C. pyramidosquamulosa, because all of them present subpyramidal squamules on the pileus and stipe surface. But the lamellae of Cystolepiota fumosifolia usually have brown spots, and it has pleurocystidia (Vellinga, 2006). Cystolepiota pyramidalis has orange white to pale orange pileus, pale yellow lamellae, which turn brownish orange when touched or mature, and ellipsoid-ovoid basidiospores (Sysouphanthong et al., 2022). The lamellae of Cystolepiota pyramidosquamulosa are yellowish white, do not change color after drying, and do not have cystidia (Qu et al., 2023).

In the phylogenetic trees (Figures 1, 2), Cystolepiota changbaishanensis and C. hetieri are sister clades, but the lamellae of the latter’s basidiomata did not change color after drying and exhibited pleurocystidia.

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, Q_v = 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), Q_m = 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.

MycoBank number: MB 849380 (Figures 7, 8).

Diagnosis: C. luteosquamulosa is distinguished from other Cystolepiota species by its light yellow to greyish yellow pileus, with greyish yellow to dark yellow warty to subpyramidal squamules, light reddish brown stipe with white to light yellow floccose squamules, and pleurocystidia and cheilocystidia absent.

Etymology: “luteo-” means yellow, and “luteosquamulosa” refers to the yellow squamules on the pileus.

Type: China, Jilin province, Jiaohe City, Hongyegu, September 6, 2021, coll. T. Bau and X. Wang (HMJAU67711), Holotype!

Description: Basidiomata small. Pileus 0.8–1.4 cm, hemispherical to obtusely conical when young, expanding to plano-convex or applanate with a slightly umbonate center with age, light yellow (1A4–A8) to greyish yellow (2B5–B8), with greyish yellow (2C7–C8) to dark yellow (3C5–C8) warty to subpyramidal squamules; margin appendiculate with veil remnants when young, and then finely appendiculate, concolorous with pileus; context white, thin. Lamellae free, white to cream, crowded, 0.1–0.3 cm wide, with 1–3 tiers of lamellulae, drying brownish orange (5C2–C6). Stipe 2.5–5.6 × 0.1–0.2 cm, subcylindrical, light reddish brown (7E5–E8), with some floccose squamules, white to light yellow (1A2–A8), with conspicuous white mycelia on the base. Annulus not visible. Odor and taste not recorded (Figures 7A–C, 8A).

Basidiospores [120,4,4] 4.9–6.3 (−6.6) × (−2.0) 2.4–3.0 (−3.3) μm, Q = 1.70–2.63, Q_v = 2.10, long ellipsoid to cylindrical, hyaline, smooth-walled under the LM, finely punctate under SEM, inamyloid, non-dextrinoid, metachromatic in cresyl blue, cyanophilous. Basidia 15–23 × 4–7 μm, clavate, 4-spored, sometimes 2-spored. Lamellar trama regular. Pleurocystidia and cheilocystidia absent. Squamules composed of loosely-arranged globose, subglobose, ovoid, 13–62 μm in diam., rarely gourd-shaped or fusiform, 17–42 × 7–16 μm, sometimes 2–4 cells are connected in a string, smooth-walled, slightly thick-walled, hyaline, or orange white (5A2–A3). Clamp connections present in all structures (Figures 7D–F, 8B–D).

Habitat: Solitary or scattered on dead leaves or soil of mixed forest.

Distribution: Northeastern China.

Additional specimens examined: China, Jilin Province, Jiaohe City, Qianjin forest farm, July 24, 2022, coll. T. Bau and L. Y. Zhu (HMJAU67810); Dunhua City, State Forest farm, July 27, 2022, coll. T. Bau, W. N. Hou and F. Guo (HMJAU67808, HMJAU69060); Huadian City, Red Rock National Forest Park, August 28, 2023, coll. T. Bau and H. Cheng (HMJAU67807). Heilongjiang Province, Yichun City, Xing’an National Forest Park, July 25, 2023, coll. T. Bau and W. N. Hou (HMJAU67809).

Notes: Macromorphologically, both C. luteosquamulosa and C. luteohemisphaerica have yellow pileus. But in the latter, the pileus is radially veined and micaceous-mealy, with broadly elliptical to elliptical basidiospores (Saar and Laessoe, 2008). C. icterina also has a yellow pileus, but it is easy to distinguish from C. lutesquamulosa by its pileus surface with finely floccose-farinose squamules, by its smaller (3.5–4.5 × 2.5 μm) and dextrinoid basidiospores and by the presence of cheilocystidia (Knudsen, 1978).

MycoBank number: MB 851388 (Figures 9, 10).

Diagnosis: The main distinguishing features of C. nivalis are the widely umbonate, white, farinose pileus, with a strongly appendiculate margin, with a farinose stipe and cystidia absent.

Etymology: “nivea” refers to snowy white pileus.

Type: China, Jilin province, Jiaohe City, Qianjin forest farm, August 25, 2023, coll. T. Bau and M. Liu (HMJAU68220), Holytype!

Description: Basidiomata small. Pileus 1.2–1.7 cm, hemispherical, then campanulate, with a broad umbo, with concolorous farinose squamules; margin appendiculate strongly farinose, concolorous with pileus; context thin, whitish. Lamellae free, crowded, white to light cream, unequal, with 1–3 tiers of lamellulae. Stipe 3.7–5.6 × 0.1–0.2 cm, central, subcylindrical to cylindrical, surface strongly farinose, white to cream, light brown (6D5–D8) to reddish brown (7E4–E8) towards the base. Annulus white, fugacious. Odorless, taste not recorded (Figures 9A–C, 10A).

Basidiospores [120,4,4] 3.8–4.7 (−4.9) × 2.0–3.0 μm, Q = 1.47–2.06 (−2.28), Q_v = 1.85, ellipsoid to cylindrical, slightly thick-walled, smooth-walled under the LM and SEM, hyaline inamyloid, non-dextrinoid, metachromatic in cresyl blue, cyanophilous. Basidia 12–17 × 3.5–5 (−6) μm, clavate, 4-spored, sometimes 2-spored, hyaline. Lamellar trama regular. Pleurocystidia and cheilocystidia absent. Pileus and stipe covering composed of globose, subglobose, pyriform cells 8–36 μm in diam., or 9–25 × 4–12 μm, sometimes 2–5 cells connected in a string, thin-walled, hyaline. Clamp connections present in all structures (Figures 9D–F, 10B–D).

Habitat: Solitary to scattered in mixed forest.

Distribution: Found only in Jilin Province, northwestern China.

Additional specimens examined: China, Jilin province, Jiaohe City, Qianjin forest farm, August 25, 2023, coll. T. Bau and H. Cheng (HMJAU68219); Huadian City, Red Rock National Forest Park, August 27, 2023, coll. T. Bau and X. Y. Zhou (HMJAU68217, HMJAU68218).

Notes: Morphologically, P. petasiformis also has a white pileus with an obvious umbonate, but it is easy to distinguish from C. nivalis by its context turns pale orange after cut, and lacks clamp connections (Vellinga and Huijser, 1998; Yang et al., 2019).

Key to species of Cystolepiota in China.

1. Pileus surface squamules fluorescent pink or greyish yellow……………………………………………………………………………2

1′. Pileus and pileus surface squamules white, cream, pale pinkish, pale yellow, light yellow brown………………………………………………………………………………………….………………………3

2. Pileus surface squamules fluorescent pink………………………………………………………………………………C. squamulosa

2′. Pileus surface squamules greyish yellow……………………………………………………………………………C. luteosquamulosa

3. Pileus and pileus surface squamules white only……………………………………..…………………………………………C. nivalis

3′. Pileus white to cream, pileus surface squamules white, cream, pale pinkish, pale yellow, light yellow brown……………………………………………………………………………………………………4

4. Lamellulae dry to greyish orange, light brown, greyish brown…………………………………………………………………5

4′. Lamellulae dry unchanged to greyish orange, light brown, greyish brown…………………………………………………………6

5. Pleurocystidia absent…………………….……………………….………………………………………………...C. changbaishanensis

5′. Pleurocystidia present, numerous…………………….……………………………………………………………………C. fumosifolia

6. Cheilocystidia present……………………………………………………………………………………………………………………7

6′. Cheilocystidia absent……………………………………………………………………………………………………………………9

7. Pleurocystidia absent…………………………………………………...……………………………………………………C. adulterina

7′. Pleurocystidia present…………………………………………………………………………………………………………………8

8. Cheilocystidia ventricose-capitate at apex, pleurocystidia rarely, occasionally clavate to fusiform……………………………… ……………………………………………………C. pseudofumosifolia

8′. Cheilocystidia capitate and cylindrical or moniliform excrescence at apex, pleurocystidia similar to cheilocystidia………………………………………………………………………………C. hetieri

9. Basidiospores strongly dextrinoid……………………………………………………………………………………C. pseudogranulosa

9′. Basidiospore inamyloid, non-dextrinoid………………………………………………………………………………………………10

10. Basidiospores surface rough under SEM………………………………………………….………………………………………….....11

10′. Basidiospores surface smooth under SEM………………………………………….………………………………………….12

11. Pileus expanding to plano-convex or applanate slightly umbonate, basidiospores (−3)3.5–4.5(−5) × 2–3 (−3.5) μm, Q_m = 1.55 ± 0.19, ovoid to ellipsoid……………………C. pseudoseminuda

11. Pileus hemispherical to convex, without umbonate, basidiospores (−3.7)4.4–5.7(−6.1) × 2–3.5 μm, Q_m = 1.89 ± 0.02, long ellipsoid…………………………………….………….C. hongshiensis

12. Pileus surface squamules irregular pyramidal……………………………………………………………………C. pyramidosquamulosa

12′. Pileus surface squamules powdery to granulose…………………………………………………………………………C. seminuda