Clitopilus fraxinicola T. Bau & Tian Y. Zhang sp. nov.Figs 2 A, 2 B, 5Etymology.The specific epithet “ fraxinicola ” is derived from Latin fraxinus (ash tree) and - cola (dweller), referring to its growth on decaying branches of the Manchurian ash (Fraxinus mandshurica Rupr.).Holotype.China. • Jilin Province, Jiaohe City, Qianjin Experimental Forest Farm, 16 June 2025, 43°57'29"N, 127°42'39"E, alt. 347 m, Tolgor Bau and Long-Hao Li LH 2561602 (FJAU 75563).Diagnosis.Basidiomata omphalinoid, signal white. Pileus centrally depressed; lamellae sparse; stipe central. Basidiospores subovoid to subfusiform with 6–8 longitudinal ridges. Gregarious on decaying branches of Fraxinus mandshurica in mixed forests.Description.Basidiomata omphalinoid. Pileus diameter 0.3–0.7 cm, initially hemispherical, later concave. When fresh, signal white (RAL 9003) to traffic white (RAL 9016); when dry, nearly white (RAL 1013). Pileus depressed at center, surface finely tomentose; margin entire, slightly incurved. Context thin, grayish white (RAL 9002); odor indistinct. Lamellae decurrent, white, sparse, unequally long. Stipe central, 0.7–2.1 cm long, 0.2 cm thick, subcylindrical, equal, solid, hyaline, signal white (RAL 9003), slightly curved in middle; surface smooth or finely tomentose; base with signal white (RAL 9003) mycelium.Basidiospores.[80 / 4 / 3] (5.9 –) 6.2–6.9 – 7.9 (– 8.3) × (3.2 –) 3.3–3.9 – 4.6 (– 4.9) µm, Q = 1.51–1.98, Q m = 1.75 (± 0.12), hyaline, subovoid to subfusiform or fusiform in profile and face view, obscurely angled in polar view with 6–8 facets produced by obscure longitudinal ridges (often indistinct under the light microscope), with minute transverse folds visible under SEM. Basidia 18–25 × 6–8 µm, clavate, 4 (2) - sterigmata. Cheilocystidia and pleurocystidia absent. Hymenophoral trama subregular, composed of subcylindrical hyphae 4–7 µm wide. Pileipellis a cutis, composed of interwoven, cylindrical, hyaline hyphae 5–8 µm in diameter, terminal cells 12–29 × 4–7 μm, subcylindrical, hyaline. Stipitipellis composed of repent, cylindrical hyphae 4–11 µm in diameter, interspersed with erect, hyaline hyphae 4–6 µm in diameter; terminal cells 15–39 × 5–8 μm, subcylindrical, hyaline, apex slightly acute or inflated. Clamp connections absent in all tissues.Habitat.Gregarious on dead wood or branches of Fraxinus mandshurica in mixed forests during summer.Distribution.Currently known only from Jilin Province, China.Additional specimens examined.China. • Jilin Province, Jiaohe City, Qianjin Experimental Forest Farm, 29 June 2025, 43°57'29"N, 127°42'39"E, alt. 347 m, Hong Cheng C 25062905 (FJAU 75564), Tian-Yu Zhang ZTY 25062909 (FJAU 75565), Wei Sun SW 25062912 (FJAU 75567).Notes.Based on its morphology and phylogenetic position, this species belongs to Clitopilus sect. Scyphoides. Morphologically, the present species resembles C. scyphoides (Fr.) Singer, but the latter possesses a larger pileus (0.5–3 cm) and longer basidiospores (6.5–8.5 × 3.5–5.0 µm) and typically grows on soil, allowing differentiation (Noordeloos 1984; Singer 1986; Bas et al. 1988). While sharing small basidiomata with C. subscyphoides W. Q. Deng et al. from Guangdong, China, the latter species differs in occurring on soil and being distributed in subtropical regions (Deng et al. 2013; Jian et al. 2023). Furthermore, it is distinguished from its five phylogenetically close relatives by key characteristics: from C. cretoalbus Izhar et al. by the latter’s possession of polymorphic cheilocystidia (subcylindrical, lageniform to filiform) and soil habitat (Izhar et al. 2023); from C. pirosylvanus Asif et al. by the latter’s pale brown pileus with a deep depression and a smaller spore Q value (Q m = 1.4) (Asif et al. 2025); from C. giovanellae (Bres.) Singer by the latter’s smooth basidiospores (Moreno et al. 2007); and from both C. zoysiae Kun L. Yang et al. and C. kamaka J. A. Cooper by their pleurotoid basidiomata with an eccentric or reduced stipe, with the latter species also recorded from Oceania (Cooper 2014; Yang et al. 2025).