The type specimen was collected by Bárcenas Peña from the Los Tuxtlas Biosphere Reserve at an elevation of 345 m (1,132 ft), where it was growing in a lowland rainforest on the bark of Astrocaryum mexicanum and Pseudolmedia oxyphyllaria.

[2] The apothecia (fruiting bodies) of Graphis marusae are lirelliform (elongated and slit-like) and flexuose (curved or twisted), typically unbranched, and prominent on the surface.

The disc of the apothecia is concealed, with a thick proper margin (border) that initially remains smooth but eventually becomes striate (striped).

The thalline margin (the part of the thallus surrounding the apothecium) is indistinct, thin, and ranges from basal to almost lateral, greenish-grey in colour.

[2] The excipulum (the cup-like structure around the apothecium) is completely carbonised (blackened and hardened), measuring 80–120 μm in width, and can be entire (smooth) to apically crenulate (scalloped at the top).