Xanthoparmelia thamnolica is a species of saxicolous (rock-dwelling), foliose lichen in the family Parmeliaceae. Found in Southern Africa, it was formally described as a new species in 1986 by the American lichenologist Mason Hale. The type specimen was collected from Cape Province at an elevation of about , where it was found in a pasture growing on sandstone boulders. The thallus is dark yellowish green in colour and measures . It contains thamnolic acid (for which the species is named) and usnic acid.