Aureoboletus velutipes Ming Zhang & T.H. Li

Zhang, Ming, Li, Tai-Hui, Wang, Chao-Qun, Zeng, Nian-Kai & Deng, Wang-Qiu, 2019, Phylogenetic overview of Aureoboletus (Boletaceae, Boletales), with descriptions of six new species from China, MycoKeys 61, pp. 111-145 : 111

Aureoboletus velutipes Ming Zhang & T.H. Li sp. nov. Figs 2L , 3I , 9 A–E

Diagnosis.

This species can be easily distinguished from others in Aureoboletus by its dry and small basidiomata, brown orange to reddish-brown pileus, light yellow to pastel yellow stipe, covered with fibrillose to tomentose squamules and smooth basidiospores 10-13 × 4-6.5 μm.

Etymology.

" velutipes " refers to the stipe, covered with fibrillose to tomentose squamules.

Type.

China, Guangdong Province, Huizhou City, Xiangtoushan National Nature Reserve, on soil under the broadleaf forest, dominated by Fagaceae trees, alt. 350 m, 2 April 2015, M. Zhang (holotype: GDGM44713).

Basidiomata small-sized. Pileus 2-4 cm wide, obtuse to convex when young, becoming broadly convex to plane at mature, fleshy, dry, covered with fibrillose to tomentose squamules, light yellow, light orange (4A4-6A4), brownish-orange (6C7-7C7), brown to reddish-brown (6D7-9D7), slightly fading to light orange to brownish-orange towards margin. Context 3-5 mm thick at stipe, firm and tough in youth, soft when matured, yellowish to white on the whole, more or less reddish-brown beneath the pileipellis, slightly changing to pastel red (7A4-9A4) when exposed. Tubes 3-5 mm deep, distinctly depressed around stipe, yellowish-white (2A2-4A2) when young, becoming pale yellow, greyish-yellow, pastel yellow to olive yellow (2A3-4A3, 1B3-2B3, 2A4-3A4, 2C6-3C6) in age, often with an olive tint, unchanging when bruised. Pores 0.5-0.8 mm in diam., mostly subangular, slightly elongated around stipe at maturity, smaller near pileus margin, concolorous with tubes. Stipe 30-60 × 5-10 mm, central, cylindrical or narrowly clavate, solid, equal to slightly enlarged downwards, covered with white, yellowish-white to yellowish-brown fibrillose to tomentose squamules, usually forming reticulation or longitudinally striate, light yellow to pastel yellow (2A4-4A4, 2A5-4A5), with white basal mycelium. Odour none. Taste mild.

Basidiospores [90/3/3] 10-13 × (4 –)5–6(– 6.5) μm, Q = (1.75 –)1.8–2.2(– 2.4), Qm = 2.08 ± 0.35, subfusiform and inequilateral in side view, oblong to ovoid in ventral view, smooth, yellowish to yellowish-brown in 5% KOH and yellow brown to dark brown in Melzer’s reagent, thin-walled. Basidia 25-30 × 9-13 μm, clavate, predominantly 4-spored but frequently also 2-spored, with sterigmata 2-3 µm long, yellowish-white to hyaline in 5% KOH, without basal clamps. Pleurocystidia 35-65 × 10-18 μm, fusiform, thin-walled. Cheilocystidia frequent, similar to pleurocystidia in shape and size. Hymenophoral trama composed of subparallel hyphae 6-10 μm broad, yellowish-white to hyaline in 5% KOH. Pileipellis a trichodermium of erect and often branched hyphae 4-17 μm in diameter, yellowish-white to hyaline in 5% KOH, dextrinoid in Melzer’s reagent; terminal cells 30-60 × 4-17 μm, cylindrical, clavate or nearly fusoid. Stipitipellis a layer of repent to suberect branching hyphae 3-15 μm in diameter, with swollen tips, terminal cells 30-70 × 11-21 μm, hyaline in 5% KOH. Clamp connections absent in all tissues.

Ecology and distribution.

Scattered on soil in subtropical forests, dominated by Fagaceae ( Castanopsis spp., Lithocarpus spp. and Quercus spp., etc). Currently known from southern China.

Additional specimens examined.

China, Guangxi Province, Guilin City, Maoershan National Nature Reserve, alt. 1380 m, 1 July 2012, M. Zhang (GDGM42608); Jiangxi Province, Jinggangshan City, Jingganshan National Nature Reserve, alt. 1000 m, 21 June 2016, H. Huang (GDGM52409).

Notes.

The obviously villose or fibrous squamulose stipe can distinguish it from other species in Aureoboletus . Aureoboletus catenarius , recently described from southwest China, is somewhat similar to A. velutipes with a dry and tomentose pileus, but A. catenarius has a cracked and light brown to reddish-brown pileus, faintly or finely fibrillose stipe and smaller basidiospores 7-9 × 3.5-5 μm ( Wu et al. 2016).

Figures

Figure 2. Basidiomata of six new species and one new combination of Aureoboletus from China. A, B A. glutinosus (A GDGM 44476 B GDGM 44477, holotype) C A. griseorufescens (GDGM 28490, holotype) D, E A. miniatoaurantiacus (D GDGM 43439 E GDGM 43282) F, G A. raphanaceus (F GDGM 45911, holotype G GDGM 52890) H, I A. sinobadius (H GDGM 44732 I GDGM 71932, holotype) J, K A. solus (GDGM 44759, holotype) L A. velutipes (L GDGM 44713, holotype). Scale bars: 2 cm.

Figure 3. Scanning electron micrograph of basidiospores of six new species and one new combination of Aureoboletus from China. A A. glutinosus (GDGM 44477, holotype) B A. griseorufescens (GDGM 28490, holotype) C, D A. miniatoaurantiacus (C GDGM 43439 D GDGM 4855) E, F A. raphanaceus (GDGM 45911, holotype) G A. sinobadius (GDGM 71932, holotype) H A. solus (GDGM 44759, holotype) I A. velutipes (GDGM 44713, holotype). Scale bars: 5 µm.

Figure 9. Aureoboletus velutipes. A Basidiospores B Pleurocystidia C Basidia and pleurocystidia D Pileipellis E Stipitipellis. Scale bars: 10 µm (A-C), 40 µm (D, E).