Aureoboletus clavatus N.K. Zeng & Ming Zhang, 2015

Zeng, Nian-Kai, Zhang, Ming & Liang, Zhi-Qun, 2015, A new species and a new combination in the genus Aureoboletus (Boletales, Boletaceae) from southern China, Phytotaxa 222 (2), pp. 129-137 : 132-133

Aureoboletus clavatus N.K. Zeng & Ming Zhang sp. nov. ( Figs. 2a–d and 3 )

MycoBank: MB812119

Etymology: referring to the pileipellis composed of a turf of clavate hyphae.

Diagnosis: Characterized by its large-sized basidiomata with slightly viscid pileus, a context stainning yellowish olivaceous, subglobose basidiospores, and the pileipellis composed of a turf of clavate hyphae.

Holotype: CHINA. Hainan Province: Qiongzhong County, Limushan Nature Reserve , elev. 850 m, 3 August 2010, N. K. Zeng 807 ( HKAS 59802 ).

Paratype: CHINA. Hainan Province: Ledong County, Jianfengling National Nature Reserve, elev. 940 m, 3 July 2013, M. Zhang (GDGM 42963).

Basidiomata medium to large-sized. Pileus 6–15 cm in diameter, subhemispherical, convex to applanate, surface slightly viscid and rugose, covered with brownish red (8C8–9C8) to reddish brown (8D8–9D8) squamules; margin slightly projecting; context 1–1.5 cm in thickness in the center of the pileus, yellowish white, the portion nearing to hymenophore changing yellowish olivaceous slowly in colour when injured. Hymenophore poroid, depressed around apex of stipe; pores angular, 0.3–0.5 mm in diameter, pale yellow to olivaceous yellow (4A3–4A4), unchanging in colour when injured; tubes 0.6–1.2 cm in length, yellowish (2A3–4A3). Stipe 5–12 × 2–5 cm, central, attenuating upward, base sometimes enlarged to subglobose; surface dry, fibrous, brownish red (8C8–9C8) to reddish brown (8D8–9D8); context yellowish white, turning yellowish olivaceous slowly in colour when injured; annulus absent. Basal mycelium white (1A1). Odor not distinct. Taste mild.

Basidia 22–30 × 9–13 μm, clavate, thin-walled, 4-spored, hyaline to colourless in KOH; sterigmata 4–5 μm in length. Basidiospores [160/8/5] (6–)7–8(–9) × (5–) 5.5–6 (–6.5) μm, Q = (1.08–)1.17–1.40(–1.50), Q m = 1.27 ± 0.09, subglobose, slightly thick-walled (up to 0.5 μm), olive brown to yellowish brown in KOH, smooth. Cheilocystidia 20–41 × 6–9 μm, abundant, subclavate, clavate or clavate-ventricose, sometimes forked, thin-walled, with yellow contents, no encrustations. Pleurocystidia 38–54 × 7–11 μm, rare, fusiform or subfusiform, thin-walled, hyaline to colourless in KOH, no encrustations. Hymenophoral trama boletoid. Pileipellis a slightly interwoven trichoderm 60–70 μm in thickness, composed of 3–7 μm in diameter, occasionally branching, yellowish brown in KOH, thin- to slightly thick-walled (up to 1 μm) hyphae; terminal cells 17–50 × 4–7 μm, clavate, with obtuse apex. Pileal trama made up of hyphae 2–5 μm in diameter, thin- to slightly thick-walled (up to 0.5 μm), hyaline to colourless in KOH. Stipitipellis hymeniform about 100 μm in thickness, composed of thin- to slightly thick-walled (up to 0.5 μm), yellowish brown in KOH, emergent hyphae with narrowly or broadly clavate, fusiform or subfusiform terminal cells (19–32 × 4–11 μm). Stipe trama composed of 6–11 μm wide, cylindrical, thin- to slightly thick-walled (up to 1 μm), hyaline to colourless in KOH, parallel hyphae. Clamp connections absent in all tissues.

Habitat: Gregarious on the ground in forests mixed with Castanopsis spp. and Cyclobalanopsis spp.

Known distribution: Southern China.

Additional materials examined: CHINA. Hainan Province: Qiongzhong county, Limushan Nature Reserve , elev. 850 m, 3 August 2010, N. K. Zeng 807-1 ( FHMU) ; Ledong county, Jianfengling National Nature Reserve , elev. 940 m, 3 July 2013, M. Zhang ( GDGM 42962 ) ; same locality, 4 July 2013, M. Zhang ( GDGM 42984 ) .

Figures

FIGURE 2. Basidiomata of Aureoboletus species. a–d. A. clavatus (a, d from HKAS 59802, holotype; b, c from N.K. Zeng 807-1); e–i. A. longicollis (e, h–i from HKAS 59808; f–g from HKAS 59810) (photo N.K. Zeng).

FIGURE 3. Microscopic features of Aureoboletus clavatus (HKAS 59802, holotype). a. Basidia and pleurocystidium. b. Basidiospores. c. Cheilocystidia. d. Pileipellis. e. Stipitipellis. Bars = 10 μm.