Pyrenula tetraspora is a species of corticolous (bark-dwelling) crustose lichen in the family Pyrenulaceae. The species is distinguished by its unusually large ascospores, with each spore-bearing sac (ascus) containing only four spores instead of the typical eight found in most related species. It forms a relatively thick pale gray crust on smooth bark in montane forests and is known only from its type locality on Cerro Guaiquinima in Venezuela at around 800 m elevation.