Fissurina simplex is a species of corticolous (bark-dwelling), crustose lichen in the family Graphidaceae.

[1] Found in India, it was formally described as a new species in 2012 by Bharati Sharma, Pradnya Khadilkar, and Urmila Makhija.

The lichen has a brown, glossy, and cracked thallus that is delimited by a black hypothalloidal region at its periphery.

The ascomata are lirellate, 0.5–1.5 mm long, simple, usually straight (sometimes curved) and the same colour as the thallus.

They are immersed to slightly raised, arising as a swelling that then cracks and gapes, and have a terminally acute structure of subcontexta-type.