Two new species of Metacampanella (Agaricales, Marasmiaceae) from China and Mongolia Author Hou, Wei-nan 0000-0002-9838-3489 Key Laboratory of Edible Fungal Resources and Utilization (North), Ministry of Agriculture and Rural Affairs, Jilin Agricultural University, Changchun 130118, China Author Ganbaatar, Burenbaatar 0000-0003-0720-2441 Key Laboratory of Edible Fungal Resources and Utilization (North), Ministry of Agriculture and Rural Affairs, Jilin Agricultural University, Changchun 130118, China & Laboratory of Plant Taxonomy and Phylogenetic, Botanic Garden and Research Institute, Mongolian Academy of Sciences, Ulaanbaatar 13330, Mongolia & School of Animal Science & Biotechnology, Mongolian University of Life Sciences, Ulaanbaatar 17024, Mongolia Author Bau, Tolgor 0000-0003-2461-9345 Key Laboratory of Edible Fungal Resources and Utilization (North), Ministry of Agriculture and Rural Affairs, Jilin Agricultural University, Changchun 130118, China text MycoKeys 2024 2024-09-10 108 227 247 journal article 302879 10.3897/mycokeys.108.131983 2b6d1731-073e-4f12-9eb2-483818fea5d3 Metacampanella tricolor (Alb. & Schwein.) T. Bau & W. N. Hou comb. nov. Figs 2 E, F , 5 Agaricus tricolor Alb. & Schwein., Consp. fung. (Leipzig): 224 (1805) Basionym. Marasmiellus tricolor (Alb. & Schwein.) Singer , Pap. Mich. Acad. Sci. 32: 128 (1948) [1946] Synonym. Type material. Holotype . China • Inner Mongolia , Tongliao City , horqin left back banner, Udantara Forest Farm , 15 July 2023 , 43 ° 1 ′ 17 ″ N , 122 ° 44 ′ 47 ″ E , alt. 345 m , Weinan Hou , H 230754 ( FJAU 69314 ). Metacampanella tricolor A basidiomata B basidiospores C basidia D basidioles E cheilocystidia F pileipellis G stipitipellis. Scale bars: 2 mm ( A ); 5 µm ( B ); 15 µm ( C – G ). Description. Pileus 4–10 mm , convex when young, applanate after maturity, slightly concave at the center, and shallow grooves on the edge. The surface of the pileus white, creamy, center light yellow, with pink tone, rough, white powder frosty fine scale, membranous. Context white, thin. Lamellae rice white to cream color, distant (L = 8–10, I = 1–2), decurrent. Stipe 6–24 × 1–2 mm , cylindrical, slightly thinner at the base, white at the top of the stipe, light yellow in the middle, brown to grayish brown at the base, densely white fine scale on the surface, fibrous, hollow. Basidiospores 8.6–11.8 × 4.8–6.3 µm, Q = 1.9, long ellipsoid, not protuberant on the front, slightly sharp at base, colorless, transparent, thin-walled, non-amyloid. Basidia 22–32 × 7.4–11 µm, clavate, 4 (2) - spored, colorless, transparent, thin-walled, base with clamp connections. Basidioles 20–30 × 5–10 µm, clavate or subfusiform, thin-walled. Trama hyphae of lamellae irregularity, 3.8–5.7 µm in width, with clamp connections, thick-walled. Cheilocystidia tetrapyrgoid, 18–27 × 5–8 µm, the main body cylindrical, irregular protrusion on the surface. Pleurocystidia absent. Terminal cellular elements of pileipellis two types : a. tetrapyrgoid, 30–47 × 6–12 µm; b. long cylindrical or long clavate, verrucous base, colorless, 37–49 × 4.4–6 µm, thick-walled. Caulocystidia three types : a. long cylindrical or long clavate, thick-walled, smooth, 23–59 × 3.7–6.6 µm; b. U-shaped, smooth, 16–28 × 3.3–6.7 µm; c. a few short clavate, base with irregular protrusion, 16–29 × 3–6.8 µm. Stipitipellis composed of cylindrical hyphae, 3.3–5.6 µm in width, parallel, pale yellow, thick-walled. Stipitipellis composed of cylindrical hyphae, 4–6 µm in width, parallel, colorless, transparent, thick-walled. Trama hyphae of stipe composed of cylindrical hyphae, 3.3–5.6 µm in width, parallel, transparent, colorless, thick-walled. Clamp connections present in all tissues. Habitat and distribution. Summer-growing, on the residues of herbaceous plants. Known from south, northwest and northeast China . Additional specimens examined. China • Inner Mongolia , Tongliao City , Liaohe Park , 19 July 2023 , 43 ° 39 ′ 10 ″ N , 122 ° 16 ′ 57 ″ E , alt. 179 m , Tolgor Bau and Weinan Hou , H 2307216 ( FJAU 69318 ) . China • Inner Mongolia , Tongliao City , horqin left back banner, Udantara Forest Farm , 15 July 2023 , 43 ° 1 ′ 17 ″ N , 122 ° 44 ′ 47 ″ E , alt. 345 m , Weinan Hou , H 230759 ( FJAU 69313 ) . China • Heilongjian , Yichun City , Beishan Park , 25 July 2023 , 47 ° 44 ′ 13 ″ N , 128 ° 53 ′ 18 ″ E , alt. 318 m , Weinan Hou , H 2307334 ( FJAU 69315 ) . China • Liaoning , Zhuanghe City , Xishan Park , 6 July 2024 , 39 ° 37 ′ 51 ″ N , 121 ° 59 ′ 51 ″ E , alt. 70 m , Weinan Hou , H 2470619 ( FJAU 69319 ) . China • Liaoning , Dalian City , Heping Park , 9 July 2024 , 38 ° 47 ′ 22 ″ N , 121 ° 8 ′ 57 ″ E , Hong Cheng , C 24070901 ( FJAU 69320 ) . Notes. Because the macroscopic morphological characteristics of Metacampanella tricolor are very close to species of Marasmiellus , Singer classified this species into Marasmiellus in the early stage ( Singer 1948 ). However, now it was observed that the microstructure characteristics of pileipellis and cheilocystidia were more in line with the definition of Metacampanella ( Petersen and Hughes 2024 ) .