Parmotrema asperum is a species of saxicolous lichen in the family Parmeliaceae. Found in Brazil, it was described as new to science in 2008. The milky-grey thallus of the lichen is up to in diameter, consisting of irregularly branched lobes measuring 2.0âÂÂ6.5 mm wide. The lichen is named for the coarse appearance of the thallus.