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 7D87E85A-A623-5E9C-97B8-B15CE2880D7B Yue Li, S. L. Liu & S. H. He Yue Li, S. L. Liu & S. H. He 2023 Agaricomycetes Peniophoraceae Scytinostroma CoL Fungi Scytinostroma beijingensis Russulales 0 133 Basidiomycota species beijingensis sp. nov.   Figs 2 , 3   Type.   China, Beijing, Haidian District,  Yangtaishan ForestPark, on dead  Pyrustree, 4 September 2022, He 7768 (BJFC 038905, holotype).   Figure 2.Basidiomes of  Scytinostroma beijingensis aHe 7768 (BJFC 038905, holotype) bHe 7201 (BJFC 036518) cHe 7203 (BJFC 036520) dHe 7220 (BJFC 036537) eHe 7668 (BJFC 038804) fHe 7759 (BJFC 038896). Scale bars: 1 cm( a-f).   Figure 3.Microscopic structures of  Scytinostroma beijingensis(from the holotypeHe 7768) abasidiospores bbasidia cbasidioles d, egloeocystidia fskeletal hyphae from hymenium gskeletal hyphae from subiculum. Scale bars: 10 µm( a-g).  Etymology. Refers to the type locality in Beijing, China.  Fruiting body. Basidiomes annual, resupinate, widely effused, closely adnate, inseparable from substrate, coriaceous, first as small patches, later confluent up to 12 cm long, 4.5 cm wide, up to 200 µmthick in section. Hymenophore smooth, greyish yellow (4B5) to greyish orange (5B5), unchanged in KOH, not cracked or deeply cracked with age; margin thinning out, adnate, fimbriate, white or concolorous with hymenophore surface. Context yellow.  Microscopic structures. Hyphal system dimitic. Context thickening, compact. Generative hyphae rare, scattered, simple-septate, colorless, thin-walled, 2-3 µmin diam., IKI-, CB-. Skeletal hyphae dominant, colorless to yellow, distinctly thick-walled, moderately branched, 2.5-4 µmin diam., weakly dextriniod, CB+. Catahymenium composed of skeletal hyphae, gloeocystidia, basidia and basidioles. Skeletal hyphae abundant, similar to those in the context, but strongly dextrinoid, frequently dichotomous-branched with acute tips, 1-2 µmwide at lowest part. Gloeocystidia abundant, SA+, with two shapes (1) ventricose, colorless, thin- to slightly thick-walled, mostly embedded, usually with contents, 28-40 x8-15 µm; (2) subcylindrical, colorless, thin- to slightly thick-walled, mostly projecting beyond the hymenium, usually with contents, 45-65 x5-7 µm. Basidia subcylindrical, slightly curved, thin-walled, colorless, smooth, with four sterigmata and a basal simple septum, 30-36 x4.5-6.5 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-, 5.5-6.5 (-6.8) x(5-) 5.2-6.2 (-6.5) µm, L = 5.9 µm, W = 5.8 µm, Q = 1.01-1.02 (n = 90/3).  Additional specimens examined.   China, Beijing, Haidian District,  Jiufeng ForestPark, on dead  Pyrustree, 26 August 2022, He 7759 (BJFC 038896); Xiangshan Park, on dead  Pyrustree, 16 July 2022, He 7668 (BJFC 038804); Miyun District, Yunmengshan Scenic Spot, on dead  Pyrusbranch, 7 August 2021, He 7201 (BJFC 036518) & He 7203 (BJFC 036520) & He 7220 (BJFC 036537).  Notes.   Scytinostroma beijingensisis characterized by having two kinds of gloeocystidia and short branched skeletal hyphae in hymenium, and growing on  Pyrus. In the phylogenetic tree (Fig. 1),  S. beijingensisformed a distinct lineage with strong support values that is sister to the clade comprising  S. renisporumBoidin, Lanq. & Gilles,  S. subrenisporum,  S. acystidiatumQ.Y. Zhang, L.S. Bian & Q. Chen and  S. caudisporumBoidin, Lanq. & Gilles.  Scytinostroma renisporumdiffers from  S. beijingensisby having cylindrical, subclavate or fusoid gloeocystidia (20-35 x6-10 µm), ovoid to reniform basidiospores (5.2-6.5 x3.2-4.8 µm) and a distribution in Cote d'Ivoire, western Africa ( Boidin and Lanquetin 1987).  Scytinostroma subrenisporumand  S. acystidiatumcan be easily distinguished from  S. beijingensisby the absence of gloeocystidia ( Zhang et al. 2023).  Scytinostroma caudisporumis unique in the group for its distinctly large basidiospores (15-30 x3-3.5 µm, Boidin and Lanquetin 1987). 2022-09-04 China Haidian District Yangtaishan Forest Yangtaishan Forest Park 1 Beijing holotype 2021-08-07 2022-08-26 2021-08-07 China Haidian District Jiufeng Forest Jiufeng Forest Park 1 Beijing