Summary:
Antrodia sinuosa is usually recognized in field by irregular, often dentate pores and pale sordid-brown color when dry. Other features include flat growth on conifer wood with the pore surface exposed, a narrow white margin, tough texture, a bitter taste, and microscopic characters. The current name in the online Species Fungorum, accessed November 16, 2020, was Amyloporia sinuosa, but the current name listed in MycoBank on the same day was Antrodia sinuosa. The description is derived from Gilbertson(1) except where noted.

Taste:
bitter

Microscopic:
spores 4-6 x 1-2 microns, cylindric to suballantoid [somewhat sausage-shaped], inamyloid; basidia 11-15 x 4-5 microns, clavate; cystidia "none, but fusoid, non-projecting cystidioles often present among the basidia, 12-20 x 3-4 microns"; hyphal system dimitic, generative hyphae 2-4.5 microns wide, thin-walled, with clamp connections, skeletal hyphae 2-5 microns wide, colorless, "thick-walled to semisolid, sinuous to straight, occasionally branched", more common in context than in trama

Spore Deposit:
white (Buczacki)

Notes:
Antrodia sinuosa has been found in BC, WA, OR, ID, AB, NS, ON, PQ, SK, AK, AZ, CO, GA, MD, MI, MT, NH, NJ, NM, NY, SD, UT, and VT - it is "Circumpolar in the boreal conifer zone", and "widely distributed through northern Asia to western Europe".

Synonyms and Alternate Names:
Polyporus sinuosus Fr.
Polyporus vaporarius Fr.