Rufoboletus hainanensis (N.K. Zeng, Zhi Q. Liang & S. Jiang) N.K. Zeng & Zhi Q. Liang, comb. nov.

≡ Butyriboletus hainanensis N.K. Zeng, Zhi Q. Liang & S. Jiang, in Liang, An, Jiang, Su & Zeng, Phytotaxa 267(4): 257 (2016).

Index Fungorum number: IF 559491; Mycobank number: MB 559491; Facesoffungi number: FoF 14871; Figs. 1, 2

Basidia 32–38 × 8–9 μm clavate, colorless to yellowish in KOH, thin-walled, four-spored; sterigmata 4–6 μm long. Basidiospores [66/3/2] (6.5–)7–9×4–5 μm, Q = (1.4–)1.5–2.13, Qm = 1.81 ± 0.18, subfusiform to ellipsoid, slightly thick-walled (up to 0.8 μm), olive brown to yellowish brown in KOH, smooth. Hymenophoral trama boletoid. Cheilocystidia 32–52×5–8 μm, abundant, subfusiform or fusiform, thin- to slightly thick-walled (up to 0.5 μm), sometimes with yellowish brown contents, without encrustations. Pleurocystidia 38–70×8–12 μm, abundant, fusiform or subfusiform, thin- to slightly thick-walled (up to 0.5 μm), sometimes with brown or golden brown contents, without encrustations. Pileipellis an intricate trichodermal type, 110–160 μm thick, composed of colorless, pale yellowish brown to yellowish brown in KOH, thin- to slightly thick-walled (up to 0.5 μm) hyphae 3–9 μm broad; terminal cells 28–44×4–11 μm, narrowly clavate or subcylindrical, with obtuse apex. Pileus trama composed of thin- to slightly thick-walled (up to 0.5 μm) hyphae 3–9 μm broad. Stipitipellis a trichoderm-like structure 90–160 μm thick, composed of thin- to slightly thick-walled (up to 0.5 μm) hyphae with narrowly or broadly clavate, subfusiform or fusiform terminal cells (14–30×6–10 μm). Stipe trama composed of cylindrical, thin to slightly thick-walled (up to 0.5 μm), parallel hyphae 4–10 μm broad. Clamp connections absent in all tissues.

Materials examined – China, Hainan Province, Yinggeling of Hainan Tropical Rainforest National Park, elev. 850 m, 26 July 2009, N.K. Zeng334 (KUN-HKAS 59816, holotype), N.K. Zeng332 (KUN-HKAS 59814, paratype), N.K. Zeng333 (KUN-HKAS 59815), 16 June 2013, N.K. Zeng1197 (FHMU2410), 31 July 2015, N.K. Zeng2418 (FHMU2437).

GenBank numbers – KUN-HKAS59814: ITS=KU317762, LSU=KF112336, TEF1-α=KF112199; FHMU2410: ITS = KU961653, LSU = KU961651, RPB2 = KU961658; FHMU2437: ITS = KU961654, LSU = KU961652, TEF1-α = KU961656, RPB2=KX453856.

Notes – Rufoboletus hainanensis was firstly described from Hainan, tropical China. The description of macrostructures has been provided by Liang et al. (2016); the microstructures have been reexamined in the present study.

Figure 1 – Rufoboletus hainanensis. a from FHMU2394. b from FHMU2410. c from HKAS 59815. d from HKAS 59816, holotype. e from HKAS 59814, paratype. Photos by N.K. Zeng

Figure 2 – Microscopic features of Rufoboletus hainanensis (FHMU2410). a Basidia and pleurocystidium. b Basidiospores. c Cheilocystidia. d Pleurocystidia. e Pileipellis. f Stipitipellis. Scale bars: 10 μm. Drawings by Y.X. Han