Polyporus brumalis

Scientific name:   Polyporus brumalis Pers.: Fr.
Derivation of name:   Polyporus means "many pores";
brumalis means "winter" referring to its appearance in cool
seasons of the year.
Synonymy:   Boletus brumalis Pers.; Polyporus brumalis
Pers. ex Fries
Common names:   Winter polypore.
Phylum:   Basidiomycota
Order:   Polyporales
Family:   Polyporaceae
Occurrence on wood substrate:  Saprobic; solitary or
grouped on decaying deciduous wood; October through
June.  
Dimensions:  Caps 1.5-10 cm wide; stipes 2.5-5 cm long
and 1.5-5 mm thick, colored like the cap or paler.  
Upper surface: Yellow-brown to dark brown or nearly
black; finely hairy.
Pore surface: Whitish; pores somewhat angular; pores 2-3
per mm.
Edibility: Inedible.
Comments: Compare to P. arcularius which has a paler,
scaly cap with a fringed margin and larger pores.

More information at MushroomExpert.com:  

    
Figure 1. Note the intensely dark cap surface and white pore
surface. Photo © Steve Nelsen.

Figure 2. Cap and pore surfaces. Photo © Steve Nelsen.

Figure 3. Specimens collected during the 2003 NEMF foray.
Photo © Gary Emberger.