Antrodia serialiformis is a species of polypore fungus in the family Fomitopsidaceae. The fungus is resupinate, consisting of a fertile spore-bearing pore surface lying flat on the underside of decaying wood, although one or more fan-shaped overlapping caps may also be formed. Although quite common in the eastern United States, it was not recognized as a distinct species until 2009, owing to its resemblance to the closely related Antrodia serialis. Differences in ecology, spore size, and DNA sequences distinguish the two lookalikes.