Fissurina submonospora is a species of corticolous (bark-dwelling), crustose lichen in the family Graphidaceae. Described in 2012 from specimens collected in India's Western Ghats, this lichen forms brownish-grey to dark brown crusts on tree bark in moist evergreen forests. It produces large single ascospores divided into brick-like compartments within each reproductive cell, a feature that distinguishes it from most related species which typically contain eight smaller spores.