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

Marcela Cáceres and Aptroot collected the type specimen from the Comunidade Cuidado in the Reserva Extrativista Cazumbá-Iracema [pt] (Acre, Brazil) at an elevation of 150 m (490 ft); there it was found growing on bark in a rainforest.

[1] The thallus of Fissurina isohypocrellina is crustose, forming a continuous, thinly corticate, slightly shiny pale greenish-brown layer.

The ascomata (spore-producing structures) are immersed in the bark, linear, often curved, sometimes branched, and feature wine-red discs with carbonised (blackened) tips.

This pigment reacts to a potassium hydroxide solution (K) by turning a vivid green, a unique feature among lichens.