Aureoboletus sinobadius 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 sinobadius Ming Zhang & T.H. Li sp. nov. Figs 2H, I , 3G , 7 A–F

Diagnosis.

This species is distinguished from other Aureoboletus species by its pastel red to reddish-brown pileus, light yellow hymenophore unchanging when bruised, salty taste and two different shapes of basidiospores.

Etymology.

" sino -" refers China, the holotype’s location of the species; " badius " means the brownish-red or chestnut pileus colour.

Type.

China, Guangdong Province, Guangzhou City, Baiyun Mountain Scenic Area, on soil and usually growing amongst moss under broadleaf forest, dominated by Fagaceae trees, alt. 280 m, 18 May 2018, M. Zhang (holotype: GDGM71932).

Description.

Basidiomata medium to large-sized. Pileus 5-10 cm wide, hemispheric when young, becoming convex to nearly plane in age, fleshy, viscid, especially when young and wet, glabrous to minutely velvet-subtomentose, slightly wrinkled, usually violet brown (10E5-8 to 12E5-8) when young, gradually fading to pastel red (8A5-10A5), brownish-red (9C7-10C7), reddish-brown to brownish-violet (9D6-11D6, 9D7-11D7) at maturity, with a thin and slightly incurved margin. Context 7-10 mm thick at centre, firm and tough in youth and later soft, white to yellowish-white, and more or less greyish-red (9C4-10C4) beneath the pileipellis, slightly changing to greyish-red (9C4-10D5) when exposed. Tubes 8-15 mm deep, light yellow to greenish-yellow (2A5, 2B5), unchanging when bruised. Pores small, 1-1.5 per mm, circular to angular, somewhat relatively larger and shallowly depressed around the stipe at maturity, unchanging when bruised; pore-surface concolorous with tubes. Stipe 40-80 × 5-9 mm, central, cylindrical or clavate, equal to slightly enlarged downwards, smooth, viscid when wet, pastel red (8A5-10A5), with a very pale flush of pale orange (5A3-6A3) fibrous stripe. Stipe context white to yellowish-white, slightly changing to greyish-red (9C4-10D5) when bruised. Basal mycelium white. Odour mild. Taste salty.

Basidiospores [150/8/5] 10 –13(– 14) × (4-) 4.5-5 (-5.5) μm, average 11.5-12.5 × 4.5-5, Q = (-2) 2.3-2.67 (-2.88), Qm = 2.44 ± 0.22, subfusiform and inequilateral in side view with an obtuse apex, oblong to ovoid in ventral view, smooth, yellowish to yellowish-brown in 5% KOH, yellow brown to dark brown in Melzer’s reagent, occasionally two different shapes in some specimens. Basidia 22-33 × 8-11 μm, clavate, predominantly 4-spored, partially 2-spored, with sterigmata 2-4 µm long, yellowish-white to hyaline in 5% KOH, without basal clamp. Pleurocystidia 27-50 × 7-13 μm, fusiform, thin-walled, usually containing golden-yellow contents at first, gradually changing from yellowish-white to hyaline in 5% KOH. Cheilocystidia frequent, 23-48 × 9-15 μm, clavate to subfusiform, thin-walled, containing golden-yellow contents at first, gradually changing yellowish-white to hyaline in 5% KOH. Hymenophoral trama composed of subparallel hyphae 4-10 μm broad, yellowish-white to hyaline in 5% KOH. Pileipellis an ixotrichodermium of erect and branched hyphae 6-12 μm in diameter, yellowish-white to hyaline in 5% KOH, dextrinoid in Melzer’s reagent; terminal cells 35-60 × 5-10 μm, cylindrical, clavate or nearly fusoid. Stipitipellis a layer of repent to suberect branched hyphae 3-10 μm in diam., hyaline in 5% KOH. Caulocystidia 30-45 × 9-18 μm, mostly swollen clavate, usually containing yellow to yellowish-brown substance at an early stage in 5% KOH. Clamp connections absent in all tissues.

Ecology and distribution.

Solitary or scattered on ground with humus and debris under Castanopsis fissa Rehder E.H. Wilson mixed with other broadleaf trees, alt. 200-300 m; known from south China.

Additional specimens examined.

China, Guangdong Province, Guangzhou City, Baiyun Mountain Scenic Area, alt. 300 m, 4 June 2015, M. Zhang (GDGM44736 and GDGM44732); Same location, alt. 300 m, 30 May 2013, M. Zhang (GDGM43275); Same location, alt. 300 m, 4 June 2013, M. Zhang (ZhangM55); Same location, alt. 280 m, 14 May 2015, M. Zhang (GDGM45920); Guangdong Province, Huizhou City, Xiangtoushan National Nature Reserve, alt. 300 m, 2 April 2015, M. Zhang (GDGM44473); Hunan Province, Chenzhou City, Jiulongjiang National Forest Park, alt. 280 m, 13 June 2015, M. Zhang (GDGM44730); Guangzhou City, Research Institute of Tropical Forestry, alt. 200 m, 4 May 2018, J. Xu (GDGM72253).

Notes.

Aureoboletus sinobadius is morphologically similar to A. auriporus , A. flaviporus (Earle) Klofac, A. gentilis , A. novoguineensis and A. venustus . However, A. auriporus differs from A. sinobadius in the pinkish cinnamon, vinaceous to vinaceous brown pileus, longer and more robust stipe covered with yellow pruina or floccosity at apex, slight acid taste and broader basidiospores 11-16 × 4-6 μm ( Pouzar 1957; Smith and Thiers 1971; Halling 1989; Both 1993; Bessette et al. 2000; Klofac 2010); A. flaviporus differs in the pale cinnamon to dark reddish-brown pileus, reddish-brown stipe usually with reticulation at the apex, acidic taste, broader basidiospores 11-15 × 4-6 μm and the known distribution in North America ( Bessette et al. 2000); A. gentilis , originally described from Europe, differs in having pinkish-brown to flesh-coloured pileus, whitish context unchanging when exposed and longer and broader basidiospores 12-15 × 5-6.5 μm ( Singer 1945; Pouzar 1957; Klofac 2010); A. novoguineensis , originally described from New Guinea, has pale pink brown or pale red context, shorter (3-4 mm deep) and sometimes compound hymenophore, acid taste and larger basidiospores (11.5-15.5 × 4.5-5.5 μm) and pleurocystidia (36-66 × 13-18 μm) ( Hongo 1973); A. venustus recently described from southern China differs by its shorter and broader basidiospores 7.5-10.5 × 5-6 μm ( Li 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 7. Aureoboletus sinobadius. A Basidiospores B Cheilocystidia and pleurocystidia C Basidia and pleurocystidia D Pileipellis E Stipitipellis. Scale bars: 10 µm (A-C); 20 µm (D, E).