Micropsalliota minor J. Q. Yan sp. nov.
MycoBank: 842891
Etymology: Referring to its small basidiomata.
Diagnosis: Differs from M. pusillissima by bigger basidiospores, which are longer than 5 µm. (Figures 2A–C, 3,10A)
Basidiomata slender (IG = 40–192). Pileus 2.5–6.0 mm in diameter, white (1A1) to cream (2A1) when young, with light brown (6C6–6D6) tone in age, hemispherical, expanding to plano-convex, surface dry, glabrous to finely powdery fibrillose, margin appendiculate. Context less than 0.3 mm thick. Lamellae 0.2–0.5 mm broad, free, subdistant, with two series of lamellulae, white (1A1) becoming light brown (6C6–6D6) as mature. Stipe 12–17 × 0.3–0.6 mm, cylindrical, hollow, white (1A1), surface with white (1A1) fibrils, which easily fall off. Annulus single, membranous, median, white (1A1) to cream (2A1), which easily falls off.
Basidiospores (5.0) 5.5–6.0 (6.5) × 3.0–3.7µm, av. = 5.7 × 3.4µm, Q = (1.40) 1.50–1.82 (1.90), ellipsoid to elongated in face view, amygdaliform in profile view, light brown, wall 0.2–0.4µm thick, apically thickened endosporium indistinct, without germ pore, inamyloid. Basidia 11–16 (17.5) × 5.5–6.5 (7.0) µm, clavate, hyaline, 2- or 4-spored. Pleurocystidia absent. Cheilocystidia (25) 29–45.5 (48) × (6.0) 6.5–11µm, hyaline, tibiiform or lageniform, apex capitate, up to 4.0–6.0µm in diameter or forked with capitate or obtuse to truncate apex. Pileipellis a cutis, hyphae 4.0–6.0µm in diameter, hyaline, constricted at the septa on some hyphae.
Habit and habitat: Scattered on moss layer in mixed forests.
Specimens examined: CHINA. Zhejiang Province, Lishui City, Qingtian County, Huixu Village, 5 Aug 2021, Jun Qing Yan, HFJAU2812, holotype; 6 Aug 2021, Jun-Qing Yan and Zhi-Heng Zeng, HFJAU2796; Jiangxi Province, Jiangxi Agricultural University, 3 Jun 2021, Jun-Qing Yan, HFJAU1259.
Notes: Micropsalliota minor formed an independent lineage in the phylogenetic tree. Morphologically, four Micropsalliota species (M. alba Heinem. and Little Flower, M. albosericea Heinem. and Leelav., M. delicatula R. L. Zhao, J. X. Li and M. Q. He, and M. tenuipes) have the same combination of small basidiomata with pileus generally less than 10 mm in diameter, white pileus, and basidiospores longer than 5.5µm as M. minor, but none of them have the forked cheilocystidia (Heinemann and Flower, 1983; Zhao et al., 2010; Li et al., 2021). Another species, M. bifida R. L. Zhao, Desjardin, Soytong and K. D. Hyde, has variable (including forked) cheilocystidia, but its basidiospores are shorter than 5µm (Zhao et al., 2010).
参考翻译：
小果小蘑菇 新物种 Micropsalliota minor J. Q. Yan sp. nov.
MycoBank编号：842891
词源：种加词minor指其小型的担子果。
该物种和M. pusillissima的区别是本种的担孢子更大，长度超过5μm。
担子果细瘦（IG=40-192）。菌盖宽2.5-6.0mm，幼时白色至奶油色，成熟后带浅褐色色调，半球形，开展至平凸形，表面干，光滑或被粉末状小纤维，边缘有悬垂的菌幕残片。菌肉不到0.3mm厚。菌褶0.2-0.5mm宽，离生，较稀疏，小菌褶2轮，白色，成熟变浅褐色。菌柄12–17 × 0.3–0.6 mm，圆柱形，中空，白色，被易脱落的白色小纤维。菌环单层，膜质，中生，白色至奶油色，容易脱落。
担孢子(5.0) 5.5–6.0 (6.5) × 3.0–3.7µm，平均长宽av. = 5.7 × 3.4µm，长宽比Q = (1.40) 1.50–1.82 (1.90)，背腹观椭圆形至长椭圆形，侧面观杏仁形，浅褐色，孢壁0.2-0.4μm厚，内孢壁顶端不明显加厚，无芽孔，非淀粉质。担子11–16 (17.5) × 5.5–6.5 (7.0) µm，棒状，透明，2或4小梗。侧生囊状体阙如。褶缘囊状体(25) 29–45.5 (48) × (6.0) 6.5–11µm，透明，长颈瓶形至烧瓶形，顶端头状膨大，宽4.0–6.0µm，有时顶端存在分支，有时顶端钝圆或平截。菌盖皮层表皮型（cutis），由宽4.0–6.0µm的菌丝组成，透明，部分菌丝在隔膜处溢缩。
生境与分布：散生在混交林苔藓层上。
研究标本: CHINA. Zhejiang Province, Lishui City, Qingtian County, Huixu Village, 5 Aug 2021, Jun Qing Yan, HFJAU2812, 主模式; 6 Aug 2021, Jun-Qing Yan and Zhi-Heng Zeng, HFJAU2796; Jiangxi Province, Jiangxi Agricultural University, 3 Jun 2021, Jun-Qing Yan, HFJAU1259.
讨论：小果小蘑菇在系统发育树上形成了单独的一个分支。形态学上，另外4个小蘑菇属物种（M. alba，M. albosericea, M. delicatula, M. tenuipes）同样拥有小型子实体，白色、不超过10mm宽的菌盖，和长度超过5.5μm的担孢子，但它们都不存在末端分支的褶缘囊状体。另一个物种，M. bifida有形态多样（包括顶端分支的）褶缘囊状体，但它的担孢子短于5μm。
