Lithothelium quadrisporum is a species of corticolous (bark-dwelling) lichen in the family Pyrenulaceae.

Found in Thailand, it was formally described as a new species in 2006 by Dutch lichenologist André Aptroot.

The type specimen was collected on the Doi Chiang Dao mountain (Chiang Mai Province) at an altitude of 1,600 m (5,200 ft).

Here, in a sheltered secondary rainforest, the thin pale green to brownish thallus of the lichen was found growing on the bark of a tree trunk.

The specific name refers to the asci, which are the only consistently four-spored asci in genus Lithothelium.