Pertusaria guineabissauensis is a species of crustose lichen in the family Pertusariaceae.

It was described as a new species in 2019 by Graciela Paz-Bermúdez, Alan Archer, and John Elix.

It grows on tree bark, producing a thick greenish-grey thallus with a dull, wrinkled surface.

The lichen is characterised by the presence of wart-shaped (verruciform) ascomata, asci that contain eight ascospores arranged in a single row (uniseriate) and the presence of the secondary chemicals stictic and hypostictic acids.

The specific epithet refers to Guinea-Bissau, where the lichen was discovered, and its only known locality.