Xanthoparmelia nomosa is a species of saxicolous (rock-dwelling), foliose lichen in the family Parmeliaceae.

The species epithet, derived from the Greek νομός (meaning "pasture"), refers to the lichen's habitat.

[2] Distinguishing features of Xanthoparmelia nomosa include its narrow, more or less straight lobes with a black lower surface, the occurrence of both isidia and lobules on the thallus surface, and the orange pigmentation of the lower medulla.

Xanthoparmelia nomosa is known to occur only at the type locality, growing on quartzite in a coastal paddock.

Other lichens that are often are found nearby include Parmelia signifera, Parmotrema ceratum, P. reticulatum, and other Xanthoparmelia species such as X. australasica and X. subprolixa.