Aureoboletus miniatoaurantiacus (Bi & Loh) Ming Zhang, N.K. Zeng & 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 miniatoaurantiacus (Bi & Loh) Ming Zhang, N.K. Zeng & T.H. Li comb. nov. Figs 2D, E , 3C, D , 10 A–D

Basionym.

Boletus miniatoaurantiacus C.S. Bi & Loh, in Bi, Loh & Zheng, Acta Bot. Yunn. 4(1): 60, 1982

Synonym.

Aureoboletus tomentosus G. Wu & Zhu L. Yang, in Wu, Li, Zhu, Zhao, Han, Cui, Li, Xu & Yang, Fungal Diversity 81: 51, 2016

Diagnosis.

In Bi et al. (1982): Pileus 1-1.6 cm latus, siccus, obtuse hemisphaerius, aurantiacus, confertim et minute villoso-tomentosus. Contexto flava, immutibili, ad stipitem 2-3 cm crasso, sapor mitis et odor nullus. Stipes centralis, 3-3.3 cm longus, 3-6 mm crassus, albidus, in parte in feriore flavus, subcylindraceus, solidus, velutinus. Tubuli albidi, immutabiles, ad stipitem breviter decurrentes, 3 mm longi, facile denudati; pori ovati, majuscules, 3 mm diam. Sporae ellipsoideae, laeves, pallido-flavae, 7-10 × 3.3-4 μm, 1 guttatae. Pleurocystidiis 35 × 6.5 μm, paucis.

Basidiomata small to medium-sized. Pileus 1.5-8 cm wide, hemispheric when young, becoming convex to nearly plane in age, fleshy, dry or viscid when wet, surface minutely tomentose or pulverous, slightly wrinkled, orange yellow, reddish-yellow, orange to reddish-orange (4A6-7A6, 4A7-7A7), commonly with a thin and slightly extended margin. Context 5-10 mm thick at centre, firm and tough in youth and, later, soft, white to yellowish-white, with more or less green tint at border contacting tubes, unchanging when exposed. Tube 3-10 mm deep, light orange to orange unchanging when bruised. Pores polygonal, 0.5-1.5 per mm, somewhat relatively larger and shallowly depressed around the stipe, orange to pale orange unchanging when bruised. Stipe 30-80 × 4-10 mm, central, solid, cylindrical or clavate, equal to slightly enlarged downwards, smooth to distinctly longitudinally streaks or broad reticulations, viscid in wet condition, concolorous with pileus. Stipe context concolorous with that of pileus, unchanging when exposed. Basal mycelium white to yellowish-white. Odour strong. Taste mild.

Basidiospores [90/3/3] (6.5 –)7–10.5(– 11) × (4 –)4.5–5.5(– 6) μm, Q = (1.42 –)1.6–2.0(– 2.3), Qm = 1.79 ± 0.18, ovoid and inequilateral in side view with an obtuse apex, 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 18-35 (45) × 7-14 μm, 4-spored, rarely 1-, 2-, 3-spored, clavate, yellowish-white to hyaline in 5% KOH, sterigmata 2-3 μm. Cheilocystidia (21) 26-55 (61) × (6) 8-12 μm, fusiform to subclavate, thin-walled, contained with bright yellow pigments. Pleurocystidia similar to cheilocystidia in shape and size, thin-walled, yellowish-white to hyaline in 5% KOH. Hymenophoral trama composed of interwoven branched hyphae 6-15 μm wide, yellowish-white to hyaline in 5% KOH. Pileipellis an entangled trichodermium to ixotrichodermium of erect hyphae 4-18 μm in diameter, composed of yellow to bright yellow vacuolar pigmented filamentous hyphae, terminal cells cylindrical, clavate or nearly fusoid. Stipitipellis a tangled layer of repent to suberect branching hyphae 7-12 μm in diameter, hyaline in 5% KOH. Caulocystidia 25-75 × 12-18 μm, common, clavate, fusoid or fusoid ventricose and usually contain yellow to yellowish-brown substance in an early stage in 5% KOH. Stipe trama composed of parallel hyphae 4-18 μm wide. Clamp connections absent in all tissues.

Ecology and distribution.

Scattered on soil in tropical to subtropical forests dominated by Fagaceae ( Castanopsis chinensis , C. fissa , Lithocarpus spp. and Quercus spp.). Currently known from southern and southwest China

Additional specimens examined.

China, Guangdong Province, Zhaoqing City, Dinghu Mountain, 6 September 1980, C.S. Bi et al. 677 (GDGM4677, holotype of B. miniatoaurantiacus ); Same locality, 14 April 1981, C. Li (GDGM5071); 11 August 1981, C.S. Bi et al. 855 (GDGM4855); Fujian Province, Zhangping City, alt. 350 m, 2 September 2009, N.K. Zeng 664, 669 (FHMU424, 429); same locality, 27 July 2013, N.K. Zeng 1294 (FHMU848); 29 July 2013, N.K. Zeng 1323 (FHMU876); 1 August 2013, N.K. Zeng 1339 (FHMU891); Guangdong Province, Guangzhou City, Tianluhu Forest Park, alt. 200 m, 29 May 2015, M. Zhang (GDGM42855); Guangdong Province, Shaoguan City, Chebaling National Nature Reserve, alt. 300 m, 3 September 2013, M. Zhang & C.Q. Wang (GDGM43282); Guangdong Province, Huizhou City, Xiangtoushan National Nature Reserve, alt. 300 m, 7 July 2015, M. Zhang (GDGM44727); Jiangxi Province, Chongyi County, Yangling National Forest Park, alt. 280 m, 14 August 2015, M. Zhang (GDGM51694 and GDGM43439); same locality, 31 August 2016, H. Huang (GDGM52888); Same locality, 1 September 2016, M. Zhang (GDGM53350); Same locality, 2 September 2016, M. Zhang (GDGM53274); Same locality, 3 September 2016, M. Zhang (GDGM53501).

Notes.

Aureoboletus miniatoaurantiacus , originally described as B. miniatoaurantiacus , is a rather common species in southern China and can be easily distinguished by its bright orange-yellow basidiomata, tomentose or pulverulent pileus surface, light orange to orange hymenophore unchanging when bruised and ovoid basidiospores. Based on a re-study of the type specimen and other collections quoted by Bi et al. in 1994, we found that the type specimen is composed of two small immature basidiomata, which are in a poor condition for morphological observation, but other voucher specimens fit well with the description of A. tomentosus . Thus, the newly described species A. tomentosus is, in fact, a synonym of A. miniatoaurantiacus , this conclusion also being supported by molecular data in this study ( Bi et al. 1982; Bi et al. 1994; Wu et al. 2016). Aureoboletus auriflammeus , originally described from North America, is similar to A. miniatoaurantiacus ; however, the former differs in having a distinctly reticulate stipe and narrower basidiospores (8-12 × 3-5 μm) ( Murrill 1908; Bessette et al. 2000).

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 10. Aureoboletus miniatoaurantiacus. A Basidiospores B Cheilocystidia C Pleurocystidia D Basidia and pleurocystidia E Pileipellis. Scale bars: 10 µm (A-D), 20 µm (E).