Caloboletus taienus (W.F. Chiu) Ming Zhang & T.H. Li, 2017

Zhang, Ming, Li, Tai Hui, Gelardi, Matteo, Song, Bin & Zhong, Xiang Jing, 2017, A new species and a new combination of Caloboletus from China, Phytotaxa 309 (2), pp. 118-126 : 122-124

Caloboletus taienus (W.F. Chiu) Ming Zhang & T.H. Li comb. nov.

MycoBank MB 820364

Basionym: Boletus taienus W.F. Chiu, Mycologia 40(2): 220 (1948).

Original description:— Pileus 5–7 cm. in diameter, hemispherical becoming plano-convex, glabrous, “Pale Olive Buff”; margin usually wavy. Tubes 5–8 mm. long, yellow, turning blue when bruised, adnate; pores “Ox-blood Red” or dark “Carmine,” about 1 mm. across. Rather angular. Stipe 6–8 cm. long, 15–20 mm. thick, brown at the basal portion, “Begonia Rose” upward, reticulate at the upper half of the stipe, slightly tapering upward. Flesh firm, white, turning bluish in the cap and pinkish in the stipe, rather fibrous. Spores pale olivaceous or rather hyaline under the microscope, elliptical to subfusiform, 8–9 × 3–4 μm (9 × 3μm).

Macroscopic characters:—Basidiomes small to medium-sized. Pileus 4–7 cm in diam, subhemispherical to convex, sometimes applanate; surface dry, olive yellow, greyish yellow to brownish yellow (2C7–5C7), smooth to covered with white to greenish yellow (1B3–3B3) fibrillose to tomentose, margin inrolled and usually wavy; context 8–15 mm thick in the centre of pileus, white, changing to light blue quickly when exposed. Hymenophore 4–8 mm deep, adnate or slightly depressed around apex of stipe; tubes yellow, greyish yellow to olive yellow (2B8–3B8, 2C8–3C8), bluing quickly when injured; pores angular, 1–3 per mm, deep red, brownish red to ruby (10C8–12C8), quickly staining dark blue to blackish when bruised. Stipe 6–8 × 0.8–2 cm, central, subcylindrical, solid, equal to slightly tapering downwards, surface dry, greyish yellow to greyish orange covered with deep red, brownish red to ruby (10C8–12C8) reticulation on the upper half of the stipe, gradually disappearing downwards; context white to pale red (10A3–12A3), turning bluish in the pileus and upper part of the stipe and pale red to dull red in the lower part when cut, basal mycelium white to yellowish white (1A2). Odour indistinct. Taste bitter.

Microscopic characters:—Basidiospores [60/1/1] 8–10.5 (–11) × (3.5–) 4–4.5(–5) μm, [Q =(1.78–)2–2.4(–2.62), Qm = 2.28 ± 0.2], oblong to subfusoid, barely inequilateral in profile, smooth, yellowish to yellowish-brown in 5% KOH and yellowish brown to dark brown in Melzer’s reagent, thin-walled. Basidia 25–31× 7–10 μm, clavate, hyaline in 5% KOH and yellowish to yellowish brown in Melzer’s reagent, 4-spored, without basal clamps, sterigmata 2–3.5 μm long. Cheilocystidia abundant, 30–50 × 8–12 μm, narrowly fusiform, thin-walled, smooth, yellowish white to hyaline in 5 % KOH, inamyloid; Pleurocystidia similar to cheilocystidia in size and shape. Hymenophoral trama subparallel to nearly bilateral, yellowish to hyaline in 5 % KOH, yellowish to yellowish brown in Melzer’s reagent, composed of branching, thin-walled hyphae 5–10 μm wide, thin-walled. Pileipellis made up of loosely entangled, occasionally branched, smooth, thin-walled, hyaline hyphae, sometimes outer surface covered with brown granular pigments not dissolving in KOH. Stipitipellis composed of broadly clavate inflated cells, yellowish white to hyaline in 5 % KOH; Stipe trama composed of longitudinally running, cylindrical cells 3–7 μm wide, thin-walled, branched, yellowish white to hyaline in 5 % KOH. Clamp connections absent.

Habit, habitat and distribution:—Solitary to scattered on soil in broadleaf forests. Known from southern and southwestern China.

Materials examined: — CHINA, Hainan Province: Ledong County, Jianfengling National Nature Reserve, 18°74′ N, 108°87′ E, alt. 800 m, 01 July 2013, Chao-Qun Wang (GDGM 44081).

Notes: — Duo to unavailable of the type specimen B. taienus , the morphological description given above was mainly depended on our new collection and combined with original description. Caloboletus taienus can be distinguished by the olive yellow to brownish yellow coloured pileus, deep red to ruby pores, reticulated stipe and small spores 8–10.5 (–11) × (3.5–) 4–4.5(–5) μm. This species is similar to C. xiangtoushanensis , but different in the colours of pileus and pores as well as the size of basidiospores (as mentioned above). Caloboletus yunnanensis Kuan Zhao & Zhu L. Yang , recently described from Yunnan Province, is different from C. taienus in its ochraceous to pallid yellow pileus, yellowish to yellowish brown pores, smooth stipe and much broader ovoid-ellipsoid basidiospores (7) 8.5–9 (10.5) × (5) 6.5–7 (8) μm ( Zhao et al. 2014).