Lithothelium grossum
Lithothelium grossum is a species of corticolous lichen in the family Pyrenulaceae. Found in China, it was formally described as a new species in 2006 by Dutch lichenologist André Aptroot. The type specimen was collected in the Xishuangbanna Tropical Botanical Garden at an altitude of ; here it was found growing on a tree trunk. Lithothelium grossum is characterized by its large hyaline ascospores, which measure 27–37 by 12–17 μm; these are the largest of hyaline-spored species in genus Lithothelium.