Carbacanthographis megalospora is a species of corticolous (bark-dwelling) lichen in the family Graphidaceae.

Found in Brazil, it was formally described as a new species in 2022 by Shirley Cunha Feuerstein and Robert Lücking.

The type specimen was collected by the first author from the Augusto Ruschi Biological Reserve (Santa Teresa, Espírito Santo) at an altitude of 800 m (2,600 ft).

The lichen has a whitish grey thallus with a thin cortex and an underlying black prothallus.

The specific epithet alludes to the large spores, the largest known in genus Carbacanthographis.