Pertusaria medullamarilla

Pertusaria medullamarilla is a species of saxicolous (rock-dwelling), crustose lichen in the family Pertusariaceae. Found on the Galápagos Islands, it was formally described as a new species in 2015 by lichenologists Alba Yánez-Ayabaca, Frank Bungartz, Alan W. Archer, and John Elix. The type specimen was collected on Pinzón Island, where it was found growing on basalt. The species epithet refers to its yellow-coloured medulla (amarilla is Spanish for yellow).