Sutorius subrufus N.K. Zeng, H. Chai & S. Jiang

Chai, Hui, Liang, Zhi-Qun, Xue, Rou, Jiang, Shuai, Luo, Shi-Hong, Wang, Yong, Wu, Lu-Ling, Tang, Li-Ping, Chen, Yun, Hong, Deng & Zeng, Nian-Kai, 2019, New and noteworthy boletes from subtropical and tropical China, MycoKeys 46, pp. 55-96 : 73-75

10. Sutorius subrufus N.K. Zeng, H. Chai & S. Jiang sp. nov. Figures 6 i–k, 13

Typification.

CHINA. Hainan Province: Qiongzhong County, Yinggeling National Nature Reserve, elev. 850 m, 29 May 2017, N.K. Zeng 3043 (FHMU 2004, holotype).

GenBank accession numbers: 28S = MH879698, ITS = MH885360, tef1 = MH879728, rpb2 = MH879745.

Etymology.

Latin, “subrufus” refers to the stipe surface and context of the species turning reddish when injured.

Description.

Basidiomata medium to large. Pileus 5-10 cm in diameter, subhemispherical to convex when young, then applanate; surface dry, finely tomentose, brown to pale reddish brown (10C2-11C3); context about 1.6 cm thick in the center of the pileus, white (6A1), changing reddish (9C3) when injured. Hymenophore poroid, adnate or slightly depressed around apex of stipe; pores angular, about 0.3 mm in diameter, pale brown (8C3), brown (7E2) to pale reddish brown (10C2), mostly unchanging in color when injured, but sometimes changing reddish; tubes about 1 cm in length, pale brown (8D3), unchanging in color when injured, but sometimes changing reddish. Stipe 6-10 × 1-2.2 cm, central, subcylindric, solid; surface dry, gray-white, but brownish yellow at base, covered with pale reddish-brown (7B2) to blackish-brown squamules, usually changing reddish when injured; context white (1D1-2), changing reddish (9C3) when injured; annulus absent; basal mycelium white (1A1). Odor indistinct.

Basidia 18-30 × 6-9 μm, clavate, thin-walled, colorless to yellowish in KOH; four-spored, sterigmata 2-3 μm in length. Basidiospores [200/24/3] (8 –)9–12(– 13.5) × 3.5-4.5 μm, Q=(2.25 –)2.50–3.00(– 3.29), Qm=2.79 ± 0.21, subfusoid and inequilateral in side view with a weak or distinct suprahilar depression, elliptic-fusiform to subfusiform in ventral view, slightly thick-walled (to 0.5 μm), olive-brown to yellowish brown in KOH, smooth. Hymenophoral trama boletoid; composed of colorless to yellowish in KOH, 5-10 μm wide, thin- to slightly thick-walled (up to 0.5 μm) hyphae. Cheilocystidia 28-45 × 7-10 μm, ventricose, fusiform or subfusiform, thin-walled, colorless to yellowish in KOH, no encrustations. Pleurocystidia 35-50 × 7-10 μm, fusiform or subfusiform, thin-walled, colorless to yellowish in KOH, no encrustations. Pileipellis a trichoderm about 100-150 μm thick, composed of rather vertically arranged, yellowish in KOH, 3.5-6 μm wide, thin-walled hyphae; terminal cells 30-43 × 3.5-6 μm, clavate or subclavate, with obtuse apex. Pileal trama made up of hyphae 4.5-10 μm in diameter, thin-walled, nearly colorless in KOH. Stipitipellis hymeniform about 60-80 μm thick, composed of thin-walled emergent hyphae, colorless in KOH, with clavate, subclavate terminal cells (22-28 × 4-9 μm), and occasionally with scattered clavate, four-spored basidia. Stipe trama composed of longitudinally arranged, parallel hyphae 4-8 μm wide, cylindrical, thin- to slightly thick-walled (to 0.5 μm), fawn to tawny in KOH, parallel hyphae. Clamp connections absent in all tissues.

Habitat.

Scattered, gregarious or caespitose on the ground in forests dominated by fagaceous trees, including Lithocarpus spp.

Distribution.

Southern China.

Additional specimens examined.

CHINA. Hainan Province: Qiongzhong County, Yinggeling National Nature Reserve, elev. 860 m, 29 May 2017, N.K. Zeng 3045 (FHMU 2006); Ledong County, Yinggeling National Nature Reserve, elev. 650 m, 27 July 2017, N.K. Zeng 3140 (FHMU 2101).

Note.

Sutorius subrufus is characterized by a brown to pale reddish-brown pileus, stipe surface and context turning reddish when injured, relatively smaller basidi ospores, and it is restricted in tropical China. It is both morphologically similar and phylogenetically related to S. eximius (Peck) Halling et al. and S. australiensis (Bougher & Thiers) Halling and N.A. Fechner. However, stipe surface and context of S. eximius does not change when injured. Moreover, S. eximius has larger basidiospores, and a distribution in North and Central America ( Singer 1947; Smith and Thiers 1971; Halling et al. 2012); S. australiensis has relatively larger basidiospores, a distribution in Australia, and is associated with Myrtaceae and Casuarinaceae ( Halling et al. 2012).