Aureoboletus raphanaceus 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 raphanaceus Ming Zhang & T.H. Li sp. nov. Figs 2F, G , 3E, F , 6 A–E

Diagnosis.

This species can be easily distinguished from other Aureoboletus taxa by its dry and yellowish-white to pinkish-white pileus covered with fibrillose to tomentose squamules, radish smell and ovoid basidiospores 7.5-9 × 5-6 μm.

Etymology.

" raphanaceus " refers to the radish smell of the new species.

Type.

China, Jiangxi Province, Chongyi Town, Yangling National Forest Park, on soil under the broadleaf forest dominated by Fagaceae trees, at 25°28'N, 114°19'E, alt. 300 m, 1 September 2016, H. Huang (holotype: GDGM45911).

Description.

Basidiomata small to medium-sized. Pileus 3-8 cm wide, hemispheric when young, becoming convex to nearly plane in age, fleshy, dry or slightly viscid when wet, covered with greenish-grey, yellowish-grey to brownish-grey (1D2-10D2) fibrillose to tomentose squamules on yellowish-white (1A2-4A2) to pinkish-white background, slightly wrinkled at disc; margin thin, slightly incurved at first, then extending. Context 8-12 mm thick at centre, firm and tough in youth, becoming soft, white, more or less pinkish, brownish-orange (5C4-7C4), greyish-red (8C4-10C4) to light brown (5D4-7D4) beneath the pileipellis, unchanging or slightly changing blue near the hymenophore when exposed. Tubes 4-7 mm deep, greyish-yellow (1B5-3B5), light yellow (1A5-3A5) to yellow (2A7-3A7), unchanging when bruised. Pores small, 0.5-1 per mm, circular to angular, somewhat relatively larger and shallowly depressed around the stipe at maturity; pore-surface concolorous with tubes, unchanging when hurt. Stipe 20-40 × 8-15 mm, central, cylindrical or clavate, equal to slightly enlarged downwards, dry, concolorous with pileus, longitudinally streaked and faintly pruinose or tomentose, with a very pale flush of pastel red (8A5-10A5) zone at apex. Stipe context white to yellowish-white, slightly changing pale yellow (2A3-4A3) when exposed, especially in the lower part. Basal mycelium white. Odour as radish. Taste mild.

Basidiospores [80/3/3] (7 –)7.5–9(– 10) × 5-6 μm, Q= (1.27 –)1.45–1.6(– 1.7), Qm = 1.51 ± 0.08, ovoid and inequilateral in side view, ovoid in ventral view, smooth, yellowish to pale brown in 5% KOH and yellowish-brown in Melzer’s reagent, thin-walled. Basidia 20-30 × 8-11 μm, clavate, 4-spored, rarely 1-, 2-, 3-spored, yellowish-white to hyaline in 5% KOH, without basal clamps, sterigmata 2-3.5 µm long. Pleurocystidia 30-60 × 8-13 μm, fusiform, thin-walled, usually containing golden-yellow contents at first, gradually changing yellowish-white to hyaline in 5% KOH. Cheilocystidia infrequent, similar to pleurocystidia in shape and size. Hymenophoral trama composed of subparallel hyphae 5-23 μm broad, yellowish-white to hyaline in 5% KOH. Pileipellis an ixotrichodermium to trichodermium of erect hyphae 4-12 μm in diameter, usually covered with yellow to brownish-yellow pigment slightly dissolving in 5% KOH, branched, yellowish-white to hyaline in 5% KOH, dextrinoid in Melzer’s reagent; terminal cells cylindrical, clavate or nearly fusoid. Stipitipellis a layer of suberect branching hyphae 4-15 μm in diameter, hyaline in 5% KOH. Caulocystidia 30-60 × 8-12 μm, numerous, in clusters, fusiform to lageniform and usually contain yellow to yellowish-brown substance in 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 Fagaceae trees mixed with other broadleaf trees, alt. 300-1300 m; June to September; Currently known from Jiangxi and Hunan Province.

Additional specimens examined.

China, Jiangxi Province, Chongyi County, Yangling National Forest Park, alt. 550 m, 1 September 2016, M. Zhang (GDGM52908); Same locality and date B. Song (GDGM53127), M. Zhang (GDGM52266 and GDGM50266), H Huang (GDGM52890); Hunan Province, Guidong Town, Bamianshan National Nature Reserve, alt. 1250 m, 18 June 2016, Z.P. Song (GDGM52543 and GDGM46333).

Notes.

The yellowish-white basidioma colour makes it easy to distinguish A. raphanaceus from the other species. Boletus orientialbus N.K. Zeng & Zhu L. Yang recently described from China is somewhat similar to A. raphanaceus in colour; however, B. orientialbus differs in having more robust basidiomata, smooth pileus, reticulate stipe and smaller basidiospores 7-10 × 4.5- 5 μm ( Zeng et al. 2013).

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 6. Aureoboletus raphanaceus. A Basidiospores B Basidia and pleurocystidia C pleurocystidia D Pileipellis E Stipitipellis. Scale bars: 10 µm (A-C), 20 µm (D, E).