This shrub-like lichen grows up to 15 centimetres wide and is typically found on tree bark or wood in coastal and arid areas of the islands.

The type specimen (holotype) was collected by Aptroot on 21 February 2006 on the eastern part of South Plaza Island in the Galapagos.

The species epithet, darwiniana, honours Charles Darwin, recognising his contributions to the study of biodiversity in the Galápagos Archipelago.

Unlike some other Ramalina species, R. darwiniana lacks soralia (specialised structures that produce powdery reproductive propagules).

In addition to apothecia, R. darwiniana has small, spherical pycnidia (structures that produce asexual spores), which are found along the margins of the branches.

[2] In terms of chemical properties, the medulla (inner layer) of the lichen reacts positively to potassium hydroxide solution (K+), turning orange-yellow and then red, indicating the presence of salazinic acid.

It typically grows on the bark and twigs of shrubs and trees, particularly in dry forests and open shrublands that are characteristic of the scrubland mosaic ecosystem.

It can be found at low elevations, typically between 1 and 250 metres above sea level, across various islands, including Santa Cruz, Santiago, Isabela,[2] and Española.