Phylogeny and taxonomy of Laetiporus (Basidiomycota, Polyporales) with descriptions of two new species from western China Author Song, Jie Author Sun, Yi-Fei Author Ji, Xing Author Dai, Yu-Cheng Author Cui, Bao-Kai text MycoKeys 2018 37 57 71 http://dx.doi.org/10.3897/mycokeys.37.26016 journal article http://dx.doi.org/10.3897/mycokeys.37.26016 1314-4049-37-57 Laetiporus medogensis J. Song & B.K. Cui Figures 2a, 3 Diagnosis. Differs from other Laetiporus species by its pinkish-buff to clay-buff pileal surface, buff-yellow pore surface and ellipsoid to ovoid basidiospores (5-6.2 x 4.2-5.2 μm ). Etymology. Medogensis (Lat.): referring to the locality (Medog County) of the type specimens. Holotype. CHINA. Xizang Auto. Reg. (Tibet), Medog County, on living tree of Abies , 21 Sep 2014, Cui 12240 (BJFC 017154). Basidiocarps. Annual, sessile to laterally substipitate, imbricate, fleshy when fresh, crumbly when dry, without odour or taste. Pileus flabelliform to dimidiate, applanate, projecting up to 9 cm, 12 cm wide and 1 cm thick. Pileal surface pinkish-buff to clay-buff when fresh, becoming pale yellow upon drying, glabrous, azonate to faintly zonate. Margin soft and slightly viscous, fawn when juvenile, fading to reddish-brown when dry. Pore surface buff-yellow when fresh, becoming pale yellow to cream when dry; sterile margin cream when fresh, up to 3 mm wide; pores angular, 2-4 per mm; dissepiments thin, entire to lacerate. Context white when fresh, becoming cream to pale yellow when dry, up to 8.5 mm thick. Tubes concolorous with pore surface, crumbly or chalky, up to 1.5 mm long. Figure 2. Basidiomata of Laetiporus species. a L. medogensis b L. xinjiangensis . Scale bars: a = 2 cm, b = 3 cm. Hyphal structure. Hyphal system dimitic; generative hyphae simple-septate; skeletal hyphae IKI- , CB- , dissolving in KOH. Generative hyphae in context infrequent, hyaline, thin-walled, occasionally branched, up to 11 µm in diam.; skeletal hyphae in context dominant, thick-walled with a wide lumen, frequently branched and interwoven, occasionally simple-septate, hyaline, 4-11 μm in diam. Generative hyphae in tubes dominant, hyaline, thin-walled, frequently branched, simple-septate, 4-5 µm in diam.; skeletal hyphae in tubes thick-walled with a wide lumen, occasionally branched and simple-septate, subparallel along the tubes, 3-5 µm in diam. Cystidia. Cystidia and other sterile hyphal elements absent. Basidia. Basidia clavate, 20-25 x 8-9 μm , bearing four sterigmata and a basal simple-septum; basidioles clavate, smaller than basidia. Spores. Basidiospores ellipsoid to ovoid, hyaline, thin-walled, smooth, IKI- , CB- , 5-6.2 x 4.2-5.2 μm , L = 5.78 μm , W = 4.73 μm , Q = 1.22-1.23 (n = 60/2). Additional specimens (paratypes) examined. CHINA. Xizang Auto. Reg. (Tibet), Medog County, on living tree of Abies , 20 Sep 2014, Cui 12218 (BJFC 017132) & Cui 12219 (BJFC 017133); 21 Sep 2014, Cui 12241 (BJFC 017155); 24 Aug 2014, Cui 12390 (BJFC 017304). Figure 3. Microscopic structures of Laetiporus medogensis (drawn from the holotype). a Basidiospores b Basidia c Basidioles d Hyphae from trama e Hyphae from context.