Herpothallon polyisidiatum is a species of corticolous (bark-dwelling), crustose lichen in the family Arthoniaceae.

Found in China, it was formally described as a new species in 2022 by Pengfei Chen and Lulu Zhang.

The type was collected from Mangshan National Forest Park (Qingyuan, Guangdong) at an elevation of 1,716 m (5,630 ft).

The lichen contains stictic acid, a lichen product that can be detected using thin-layer chromatography.

The species epithet refers to polyisidiatum refers to the pseudisidia, which are plentiful in this species.