Pertusaria thailandica is a species of corticolous (bark-dwelling), crustose lichen in the family Pertusariaceae. Found in Thailand, it was formally described as a new species in 2005 by Sureeporn Jariangprasert. The type specimen was collected by the author from Doi SuthepâÂÂPui National Park (Chiang Mai province) at an altitude of , where it was found growing on the bark of Cinchona. The species epithet combines the country of the type locality with the Latin suffix -ensis ("place of origin").
Pertusaria thailandica has a smooth, dull, greyish-green thallus that lacks soredia and isidia. It has many apothecia that measure 0.3âÂÂ1.5 mm in diameter. Its ascospores, which number 3 or 4 per ascus, are smooth, , somewhat to ellipsoid in shape, and measure 80âÂÂ108 by 34âÂÂ44 üm. The lichen is common in several Thai national parks in various parts of the country, at elevations ranging between . It contains several homologues of the lichen product 2'-O-methylperlatolic acid.