Buellia nashii is a species of lichen characterized by its crustose thallus, typically found in the Sonoran Desert Region and adjacent areas.

The species is named in honor of Dr. Thomas H. Nash III, a notable lichenologist and the Ph.D. supervisor of the author.

[1] The thallus appears as a crust, dense in texture, showcasing a spectrum of hues ranging from ivory to deep brown or gray.

[4][2] Buellia nashii is commonly found on a variety of siliceous rock substrates, occasionally on sandstones with small amounts of carbonates.

While both species have similar thalli, B. nashii contains norstictic acid and exhibits a characteristic aeruginose pigment in the outer exciple cells.