Basidiomata annual, medium to large, centrally stipitate, solitary to gregarious (Fig. 1a, b, c). Pileus 6.5–17 cm in diameter, convex to flat, slightly concave at centre when mature, black (4F8) to dark grey (13D1) when young, turning pastel brown (6D5–6E5) when mature; surface covered with concolorous to bark brown (3F3–3F4) tomentose squamules when mature or aged; margin undulate. Context 0.7–1.3 cm thick at centre, white (1A1), darkening when bruised, becoming light grey (28A2) when dry. Hymenophore slightly decurrent; surface white (1A1), becoming light grey (28A2) when damaged, pores subangular to angular or irregular, 2–4 per mm; tubes concolorous with hymenophoral surface, darkening when bruised, up to 0.3 cm long. Stipe 5–13 × 2–3 cm, solid, clavate to subcylindrical, concolorous with pileal surface or much paler; basal mycelium white (2A1).

a

b

c

d

e

f

Figure 1.

Basidiomata of Boletopsis species from China:

a: Boletopsis longipes (KUN-HKAS 136927, holotype, photo by Yan-Chun Li);   
b: Boletopsis longipes (KUN-HKAS 113275, photo by Mei-Xiang Li);  
c: Boletopsis longipes (KUN-HKAS 59482, photo by Yan-Chun Li);  
d: Boletopsis macrocarpa (KUN-HKAS 120843, photo by Zhen Wang);   
e: Boletopsis macrocarpa (KUN-HKAS 120843, photo by Zhen Wang);  
f: Boletopsis tibetana (KUN-HKAS 94064, photo by Bang Feng).  

Hyphal system monomitic. Generative hyphae with clamp connections. Basidia thin-walled, 15–36 × 7–15 μm, clavate to cylindrical, sometimes flexuous or ventricose with a peduncle, 4-spored, clamped at base, hyaline in KOH, yellowish to pale yellow in Melzer's Reagent (Fig. 2a). Basidiospores [122/6/5] 5–7 (8) × (3.5) 4–6 μm, Q = 1–1.75, Q_m = 1.21 ± 0.16, globose to oblong, acyanophilic and non-dextrinoid, hyaline to pale yellow in KOH; ornamentation on the surface tuberculate and sometimes furcate (Fig. 2b; Fig. 3a, b). Cystidia absent. Tube tramal hyphae thin-walled, 2–4 μm wide, cylindrical, interwoven, hyaline in KOH. Hyphae of pileipellis thin-walled, 2–7 (9) μm wide, cylindrical, interwoven and occasionally subparallel, hyaline to faint olivaceous in KOH; terminal cells (15) 18–50 (72) × (1) 3–7.5 (9) μm (Fig. 2c). Pileal tramal hyphae thin-walled, up to 26 μm wide, inflated to filamentous, interwoven, hyaline in KOH. Hyphae of stipitipellis thin-walled, 2–7 (10) μm wide, cylindrical, interwoven or subparallel, frequently branched, faint olivaceous in KOH (Fig. 2d).

Figure 2.  

Microscopic features of Boletopsis longipes (KUN-HKAS 136927, holotype). a structure of the longitudinal section of a tube; b basidiospores; c pileipellis; d stipitipellis. Scale bars: a, c = 20 μm, b = 5 μm.

a

b

c

d

e

f

Figure 3.

Basidiospores of Boletopsis species from China under SEM:

a: Boletopsis longipes (KUN-HKAS 136927, type);  
b: Boletopsis longipes (KUN-HKAS 136927, type);  
c: Boletopsis macrocarrpa (KUN-HKAS 116743);  
d: Boletopsis macrocarrpa (KUN-HKAS 116743);  
e: Boletopsis tibetana (KUN-HKAS 94064);  
f: Boletopsis tibetana (KUN-HKAS 94064).  

Boletopsis longipes differs from other species of the genus by its pastel brown pileus when mature, relatively slender stipes 5–13 × 2–3 cm, large basidia 15–36 × 7–15 μm and its occurrence in mixed forests dominated by trees of Quercus sp. and Pinus yunnanensis at an altitude ranging from 1000 m to 2600 m.

“Longipes” reffering to the relatively long-footed basidiomata.

Currently known from Yunnan Province, China.

Growing on the ground in a moist environment in mixed forests dominated by trees of the families Fagaceae (Quercus sp.) and Pinaceae (Pinus yunnanensis).

Boletopsis longipes is characterised by its black to dark grey pileus that turns pastel brown when mature, concolorous to bark brown squamules on the surface, relatively long stipes measuring 5–13 × 2–3 cm, white mycelia at the base of stipe, large basidia measuring 15–36 × 7–15 μm and solitary to gregarious occurrence in mixed forests dominated by trees of Quercus sp. and Pinus yunnanensis at an altitude ranging from 1000 m to 2600 m. This new species represents the ninth member of the genus and the third one from China. Morphologically, B. longipes is similar to B. leucomelaena and B. watlingii in their somewhat black to brown pileus, angular to irregular hymenophoral pores and somewhat decurrent hymenophore. However, B. leucomelaena is characterised by its large hymenophoral pores 1–3 per mm (vs. 2-4/mm in B. longipes), bright orange mycelia at the base of stipe, narrow basidia 17–27 × 5.5–8.5 μm (vs. 15–36 × 7–15 μm in B. longipes) and growing in dense clusters of three to ten or less often solitarily in forests dominated by trees of the genus Picea in Europe (Niemelä and Saarenoksa 1989, Watling and Milne 2008). Boletopsis watlingii has a dark sooty-brown to greyish-brown pileus with greenish tints, white context turning greyish-violet then greyish-black (especially in the stipe) when damaged, vivid orange mycelia at the base of stipe and relatively small basidiospores measuring 4.5–4.8 (5) × 3.5–4.5 μm (Blanco-Dios 2018). Boletopsis longipes and B. macrocarpa both have large basidiomata, white context when fresh and large basidia in Yunnan Province, China. However, B. macrocarpa has a cream to greyish-brown pileus which is up to 21 cm wide, a stout stipe which is up to 8.5 cm long and 5 cm wide and ash-grey or concolorous with pileal surface and a distribution in pure Pinus forest with altitude ranging from 2400 m to 3400 m (Zhou et al. 2022).

Basidiomata annual, medium to large, centrally stipitate, solitary to gregarious (Fig. 1d, e). Pileus 6.5–21 cm in diameter, roundish to irregular, slightly depressed at centre, cream (5A2) to greyish-brown (5E6), becoming pale brownish-grey (5D3) to black when dry; margin occasionally cream, undulate. Context white (1A1), becoming pale mouse-grey (2B/C2) when dry. Hymenophore slightly decurrent; surface white (1A1) to cream (5A2), becoming clay buff (6D4) to fawn (7D/E4) when dry, pores subangular to angular or irregular, 1–3 per mm; tubes concolorous with hymenophoral surface, turning fawn (6D7) when bruised, up to 0.5 cm long. Stipe up to 8.5 cm long and 5.5 cm wide, solid, subcylindrical, pale ash-grey (17B1) or concolorous with pileal surface.

Hyphal system monomitic. Generative hyphae with clamp connections. Basidia thin-walled, 18–45 × 5.5–10 μm, clavate to cylindrical, sometimes flexuous or ventricose with a peduncle, 4-spored, clamped at base, hyaline in KOH (Fig. 4a). Basidiospores [60/3/3] (4.5) 5–6 × (3.5) 4–5 (5.5) μm, Q = 1–1.38 (1.5), Q_m = 1.20 ± 0.13, globose to oblong, acyanophilic and non-dextrinoid, hyaline to pale yellow in KOH; ornamentation on the surface tuberculate and sometimes furcate (Fig. 3c, d; Fig. 4b). Cystidia absent. Tube tramal hyphae thin-walled, 2–4 μm wide, cylindrical, interwoven and occasionally subparallel in a bunch, hyaline in KOH. Hyphae of pileipellis thin-walled, 3–9 μm wide, cylindrical, interwoven and occasionally subparallel, hyaline to faint olivaceous in KOH; terminal cells 22–53 (56) × (3) 4–7 (9) μm (Fig. 4c). Pileal tramal hyphae thin-walled, 4–44 μm wide, inflated, sometimes branched, interwoven, hyaline in KOH. Hyphae of stipitipellis thin-walled, 3–20 μm wide, cylindrical, parallel, rarely branched, faint olivaceous in KOH.

Figure 4.  

Microscopic features of Boletopsis macrocarpa (KUN-HKAS 120843). a basidia and basidioles; b basidiospores; c pileipellis. Scale bars: a,c = 20 μm, b = 5 μm.

Currently known from Yunnan Province, China.

Growing on the ground in the pure coniferous forests dominated by trees of the genus Pinus (Pinus yunnanensis) at an altitude ranging from 2400 m to 3400 m.

Boletopsis macrocarpa is characterised by its large pileus (6.5–21 cm wide) with cream to greyish-brown surface, white to cream hymenophoral surface, solitary to gregarious in coniferous forests of Pinus yunnanensis in slightly dry environments at a high altitude ranging from 2400 m to 3400 m. Morphologically, B. macrocarpa is similar to B. grisea in their somewhat greyish-tinged pileus, white to cream hymenophoral surface and distribution in the pure Pinus forests. However, B. grisea originally described from Europe is characterised by its grey pileus, short stipes 2–6 cm long (vs. 8.5 cm long in B. macrocarpa), small pores 2–4/mm (vs. 1–3/mm in B. macrocarpa), gloeoplerous hyphae in pileipellis and narrow basidiospores (4.2) 5–6 (6.5) × (3.2) 3.9–4.5 (5.1) [vs. (4.5) 5–6 × (3.5) 4–5 (5.5) μm in B. macrocarpa] (Peck 1873, Niemelä and Saarenoksa 1989). In our re-examination of B. macrocarpa, we found larger basidia measuring 18–45 × 5.5–10 μm (14–19 × 6–7 μm in the protologue) and wider hyphae of pileal trama measuring 4–44 μm wide (5–25 μm wide in original description) than those in the protologue of Zhou et al. (2022).

Basidiomata annual, medium, centrally stipitate, solitary to gregarious (Fig. 1f). Pileus up to 12 cm in diameter, convex or irregular, clay buff (5C3) to dark brown (5F7), becoming greyish-brown (4C3) to black when dry; margin undulate and incurved. Context white (1A1), becoming pale brown (1B3) when dry. Hymenophore slightly decurrent, surface white (1A1), becoming clay buff (6D4) to fawn (7D/E4) when dry; hymenophoral pores round to angular or irregular, 1–4 per mm; tubes concolorous with hymenophoral surface, darkening when bruised. Stipe up to 9 cm long and 2 cm wide, solid, subcylindrical or tapering towards the base, concolorous with pileal surface.

Hyphal system monomitic. Generative hyphae with clamp connections. Basidia thin-walled, 19–25 (35) × 8–11 μm, clavate to cylindrical, sometimes flexuous or ventricose with a peduncle, 4-spored, clamped at base, hyaline in KOH (Fig. 5a). Basidiospores [20/1/1] 5–6 (6.5) × 4–5.5 (6) μm, Q = 1–1.25 (1.5), Q_m = 1.12 ± 0.13, globose to oblong, acyanophilic and non-dextrinoid, hyaline to pale yellow in KOH; ornamentation on the surface tuberculate and sometimes furcate (Fig. 3e, f; Fig. 5b). Cystidia absent. Tube tramal hyphae thin-walled, 2–4 μm wide, cylindrical, sometimes branched, interwoven and occasionally subparallel in a bunch, hyaline in KOH. Hyphae of pileipellis thin-walled, 4–10 μm wide, cylindrical with finger-shaped tips, sometimes branched, interwoven, faint olivaceous in KOH; terminal cells (37) 47–77 × 4–6 μm (Fig. 5c). Pileal tramal hyphae thin-walled, 6–30 μm wide, inflated, rarely branched, interwoven and occasionally subparallel in a bunch, hyaline in KOH. Hyphae of stipitipellis thin-walled to slightly-thick wall (up to 0.7 μm thick), 2–8 μm wide, cylindrical, interwoven, frequently branched, hyaline in KOH.

Figure 5.  

Microscopic features of Boletopsis tibetana (KUN-HKAS 94064). a basidia and basidioles; b basidiospores; c pileipellis. Scale bars: a, c = 20 μm, b = 5 μm.

Currently known from Tibet, China.

Growing on the ground in forests dominated by trees of the families Fagaceae (Quercus sp.) and Pinaceae (Picea balfouriana) or in pure Picea forests dominated by P. balfouriana at an altitude ranging from 2900 m to 3350 m.

Boletopsis tibetana is characterised by its clay buff to dark brown pileus, gloeoplerous hyphae in pileipellis and context, solitary to gregarious in mixed forests dominated by Picea and Quercus or in pure Picea forests at an altitude ranging from 2900 m to 3350 m. Boletopsis tibetana resembles B. leucomelaena by its solitary to gregarious habitat, frequently branched hyphae of stipitipellis and distribution in forests dominated by tres of the genus Picea. However, B. leucomelaena has greyish sepia or black-brown pileus often with a tinge of magenta, large pores (1–3 per mm) and a distribution in Europe (Niemelä and Saarenoksa 1989). In our re-examination of B. tibetana, we found wider basidia (19–35 × 8–11 μm) than those in the protologue (13–25 × 6–8 μm) (Zhou et al. 2022).