Sporangia grouped, stalked, 1.5–2.0 mm in total height. Sporotheca subglobose, dark purple brown to near black, 0.55–0.65 mm in diameter. Hypothallus membranous, reddish brown. Peridium single, membranous, dark greyish brown to nearly black, haloed, irregularly cracked from the top, part remaining like a high cup. Stalk stout, erect, cylindrical, attenuate toward the apex, dark brown to blackish, 1.0– 1.5 mm long, filled with whitish, rhombic crystals of lime. Columella concolorous with the stalk, capitate form, reaching the middle of the sporotheca, filled with lime. Capillitium white, rigid and fragile, almost entirely limy, merging with the columella, branched and anastomosed, as a tridimensional net. Spores black in mass, dark brown by transmitted light, spherical, 12.0–13.5 µm in diameter, roughly reticulated with irregular warts, making a small number of meshes to a hemisphere.

Specimen examined:— CHINA. Anhui Province: Yuexi County, Yaoluoping Nature Reserve, 30°98′64″N, 116°09′39″E, elevation 1089 m, on dead bark, 21 Oct 2021, collected by Que Du and Wenlong Song (HFNNU 8503, HFNNU 8504).

Distribution:— Costa Rica (Lado et al. 2018), Wales (Lister & Lister 1904), Great Britain, Ireland, Germany (Hosltein), Sandwich Islands, France and Nepal (GBIF), Poland (Stojanowaska & Panek 2003), and China (this study).

Comments:— Craterium was established by Trentepohl in 1797, and 19 species have been reported and accepted in the world (Lado 2005 –2022). Prior to now, twelve species have been reported in China (Li & Li 1989, Li et al. 2008 b, Zhang & Li 2013, Zhao et al. 2018, Zhang et al. 2020), which are C. aureum (Schumach.) Rostaf., C. concinnum Rex, C. leucocephalum (Pers. ex J.F. Gmel.) Ditmar, C. microcarpum H.Z. Li, Yu Li & Shuang L. Chen, C. minutum (Leers) Fr., C. obovatum Peck, C. rubronodum G. Lister, C. corniculatum B. Zhang & Yu Li, C. subpurpurea B. Zhang & Yu Li, C. yichunense S.Y. Liu, F.Y. Zhao & Y. Li, C. dictyosporum (Rostaf.) H. Neubert and C. aureomagnum Hooff & Nann. -Bremek. To our knowledge, this is the first report of C. muscorum from China. Lister & Lister (1904), who originally described this species as Badhamia rubiginosa var. globosa Lister & G. Lister, found it in the north of Wales. Ing (1982) clarified the nomenclatural status of this species, and named it C. muscorum. Our specimens were collected from mossy bark in autumn, supporting the affinity of this species for bryophytes and colder wet environments (Lado et al. 2018). Of the known species of Craterium, C. muscorum is similar only to C. dictyosporum in having irregularly dehiscing sporocarps, rarely circumscissile, and subreticulate or reticulate spores (Neubert et al. 1995, Zhao et al. 2018). However, the reticulation of the spores is almost complete, and with a prominent edge in C. muscorum, sets them apart.