Lithothelium quadrisporum

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 1600 m. 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.