Phylum：Basidiomycota　>>　Class： Basidiomycetes　>>　 Order： Boletales 
   
 
　BCRC Number： NO BCRC Number!  
   
　Scientific Name： Porphyrellus atrofuscus
 
   
   
　Author：

Porphyrellus atrofuscus Dick & Snell, Mycologia 52: 449. 1960.
   
 
 
 
 
　Description： Pileus 3-7 cm broad, convex, margin decurved, surface dry and velutinous, dark olivaceous-brown, context white, becoming bluing-gray when cut. Tubes 3-6 mm deep, depressed to more or less free, whitish, becoming honey yellow at first, then grayish upon exposure. Pores whitish at first, becoming ochraceous to a reddish-fawn color. Stipes 3.5-7 cm long, 4-7 mm thick, equal or tapering upward, solid, yellowish in the cortex in the apical and middle region but reddish in base when cut, slowly changing to grayish except the base; surface nearly concolorous with pileus or lighter, minutely and closely furfuraceous at first, becoming to rasied a brownish striae or furfurescence on a yellowish ground when elongated. Spore print chestnut brown. Spores 12.5-16.5 × 5.5-6 μm, subellipsoid or oblong-ellipsoid. Basidia 30-35 × 13-15 μm, clavate, sterigmata four, 4-5 μm long. Pleurocystidia 65-85 × 10-15 μm, stalked, somewhat ampullaceous with a elongated and poited tip. Tube trama of hyphae divergent from a central strand, 6-7 μm wide, hyaline, thin-walled and smooth.
 
 
 
 
 
　Specimens：

Taiwan, Nantou: Shanlinhsi, alt. 1750m, 18 Sept 1996, Chen CM 1415.
 
 
 
　Habitat： Scattered under broad-leaved forest.
 
 
 
　Distribution：

Taiwan, North America.
 
 
 
　References：

Chen, CM et al. 1998.
   
   
   
　Provided：

C. M. Chen
 
 
　Note： The distinctive features appear to be the sooty-olivaceous, velutinous pileus with flesh whitish blackening to grayish on exposure. As we have observed this species by using scanning electron microscopy, the spore surface morphology are relatively smooth in contrast to those of A. gracilis (Pk.) Sing. which is perforate-punctate.