Phylum:Basidiomycota >> Class: Basidiomycetes >>  Order: Boletales 
 BCRC Number NO BCRC Number!  
 Scientific Name: Boletus umbriniporus

Boletus umbriniporus Hongo, Journ. Jap. Bot. 44: 235-237. 1969.

 Description: Pileus 4-9 cm broad, semiglobose at first, expanding to plano-convex, surface dry and minutely tomentous, color dull blue at first to umbrinous or olive-gray in age, context yellow, cyanescent when cut or bruised. Tubes nearly free from stipe, 0.5-0.8 cm deep, color umbrinous at center and pale to olive-yellow at margin, cyanescent where injured, pores minutely circular, about 2-3 per mm. Stipe 4-8 cm long, 0.6-1.0 cm broad, subequal and generally thicker at base, surface lemon-chrome, floccose with dull blue dots composed of grayish hyphae, base with several thick and brownish mycelium, context solid, color yellow, staining slightly dull blue when cut and rubellous at base. Spores 9.5-12 × 4-5.5 μm, smooth, wall slightly thickened, subcylindrical to subfusiformic, dingy melleous in KOH, weakly ochraceous in Melzer's reagent. Basidia clavate, 28-33 × 10.5-11.5 μm, 4-spored, sterigmata 6-8 μm long, basal septa without clamp, hyaline in KOH, slightly yellowish in Melzer's reagent. Pleurocystidia abundant, conspicuous, 48-67 × 16-20 μm, ventricose-rostrate, apex subacute to rounded, thin-walled, yellowish to hyaline in KOH, filled with distinctive yellow content in Melzer's reagent. Cheilocystidia similar to pleurocystidia but smaller, the neck often flexuous, content dull yellow in material revived in KOH. Tube trama of more or less parallel hyphae diverging to subhymenium, hyaline to yellow in KOH, inamyloid. Pileus cuticle a strong trichodermium, the elements 8-13(16) μm wide and arranged in a distinct palisade, the cells long and often flexuous but essentially tubular, end-cells elongate and apex mostly obtuse to rounded, tubular to weakly cystidioid, content brownish in KOH.

Taiwan, Kaohsiung: Terngjy, alt. 1800 m, 6 Jul 2000, Chen CM. 2370.

 Habitat: Scattered under broad-leaved forest.

Taiwan, Japan, China (Guizhow).


Zang, M. 1999; Chen, CM et al. 2002.


C. M. Chen

 Note: B. umbriniporus belongs to the section Nigaris, which is distinguishable from the section Rubropori by having a character of combining blackish pores and stipe without squamulose (Zang 1999). It is also characterized by its yellow flesh, which changes to pallid blue and rubellouse base of stipe when exposed to air. B. umbriniporus is closely related to Boletus nigrican Zang of the section Nigris, but the two species are distinguishable in the field. B. umbriniporus has a dark brown pileus, non-reticulate stipe, and cyanescent tube when bruised, whereas B. nigrican has intense black pileus, reticulate stipe, and reddening tube. Also, B. umbriniporus has pleurocystidia of 48-67×16-20 um in size, which is larger than 34-48×8-12 μm for B. nigrican, but the former has spores of 4-4.5 μm in breadth, which is smaller than 5-5.6 μm of B. nigrican.