Species diversity and taxonomy of Scytinostroma sensu stricto (Russulales, Basidiomycota) with descriptions of four new species from China Li, Yue Xu, Wei-Qi Liu, Shi-Liang Yang, Ning He, Shuang-Hui MycoKeys 2023 2023-06-13 98 133 152 AF3960CF-734C-5E44-A411-1F19AC3DD68C Yue Li, S. L. Liu & S. H. He Yue Li, S. L. Liu & S. H. He 2023 Agaricomycetes Peniophoraceae Scytinostroma CoL Fungi Scytinostroma boidinii Russulales 0 133 Basidiomycota species boidinii sp. nov.   Figs 4 , 5   Type.   China, Beijing, Mentougou District,  Xiaolongmen ForestPark, on dead angiosperm branch, 28 August 2020, He 6911 (BJFC 033860, holotype).   Figure 4.Basidiomes of  Scytinostroma boidinii aHe 6911 (BJFC 033860, holotype) bHe 4985 (BJFC 024503) cHe 7465a (BJFC 038600) dHe 7465b (BJFC 038601). Scale bars: 1 cm( a-d).   Figure 5.Microscopic structures of  Scytinostroma boidinii(from the holotypeHe 6911) abasidiospores bbasidia cbasidioles dgloeocystidia eskeletal hyphae from hymenium fskeletal hyphae from subiculum. Scale bars: 10 µm( a-f).  Etymology. Named to honor Dr. Jacques Boidin (Lyon, France) who contributed much to the taxonomy of  Scytinostroma.  Fruiting body. Basidiomes annual, resupinate, widely effused, closely adnate, inseparable from substrate, membranaceous to coriaceous, first as small patches, later confluent up to 9 cm long, 3.5 cm wide, up to 300 µmthick in section. Hymenophore smooth, pale yellow (4A3), greyish yellow (4B4) to greyish orange [5B(3-4)], unchanged in KOH, not cracked; margin thinning out, adnate, fimbriate, white or concolorous with hymenophore surface. Context pale yellow.  Microscopic structures. Hyphal system dimitic. Context thickening, compact. Generative hyphae rare, scattered, simple-septate, colorless, slightly thick-walled, 2-3 µmin diam., IKI-, CB-. Skeletal hyphae dominant, colorless to yellow, distinctly thick-walled, moderately branched, 1.5-2 µmin diam., dextriniod, CB+. Catahymenium composed of skeletal hyphae, gloeocystidia, basidia and basidioles. Skeletal hyphae abundant, similar to those in the context, but strongly dextrinoid, dichotomous-branched with acute tips, 1-1.5 µmwide at lowest part. Gloeocystidia abundant, subcylindrical to subfusiform, colorless, slightly thick-walled, with or without contents, weakly SA+, 50-80 x5-10 µm. Basidia subclavate to subcylindrical, thin-walled, colorless, smooth, with four sterigmata and a basal simple septum, 30-50 x4-7 µm; basidioles in shape similar to basidia, but slightly smaller. Basidiospores subglobose, with a distinct apiculus, thin-walled, colorless, smooth, occasionally with oil-drops, amyloid, CB-, (4.5-) 5-5.5 (-6.5) x(4-) 4.5-5.5 (-6.2) µm, L = 5.1 µm, W = 5.0 µm, Q = 1.02-1.04 (n = 60/2).  Additional specimens examined.   China, Beijing, Mentougou District, Lingshan Scenic Spot, on dead angiosperm branch, 10 April 2022, He7465a (BJFC 038600) & He7465b (BJFC 038601);  Gansu Province, Tianshui County, Dangchuan ForestFarm, on dead  Quercustree, 9 August 2015, He2499 (BJFC 020952);  Hebei Province, Xinglong County, Wulingshan Nature Reserve, on dead angiosperm branch, 2 September 2017, He4985 (BJFC 024503);  Jilin Province, Jiaohe County, forestry experimental area, on fallen angiosperm trunk, 3 September 2017, He5138 (BJFC 024656).  Notes.   Scytinostroma boidiniiis characterized by the relatively long gloeocystidia and subglobose basidiospores. In the phylogenetic tree (Fig. 1),  S. boidiniiformed a distinct lineage sister to  S. alutumLanq., which differs in having cracked basidiomes, slightly larger basidiospores (5-7 x5-7.5 µm) and a distribution in France, Spain and Pakistan ( Boidin and Lanquetin 1987; Bernicchia and Gorjon2010).  Scytinostroma yunnanenseC.L. Zhao from Yunnan Province, southwestern China, has similar-sized basidiospores (4.5-5.5 x4.2-5.2 µm) to  S. boidinii, but differs in having white to cream hymenophore, smaller gloeocystidia (28-33 x4-5 µm) and smaller basidia (21-28 x4-5.5 µm, Wang et al. 2020). 2020-08-28 China Mentougou District Xiaolongmen Forest Xiaolongmen Forest Park 1 Beijing holotype 2022-04-10 He China Lingshan Scenic Spot Mentougou District 1 Beijing 2015-08-09 He China Tianshui County Dangchuan Forest 1 Gansu Province 2017-09-02 He China Xinglong County Wulingshan Nature Reserve 1 Hebei Province 2017-09-03 He China Jiaohe County Jiaohe County 1 Jilin Province