The species epithet honours the Spanish botanist Rosario Gavilán, who accompanied the authors during their fieldwork in South Africa.

[2] The lichen species Harpidium gavilaniae has a crustose, effigurate thallus that can be rounded or ellipsoid and spans up to 2.5 cm in diameter.

The areoles, which are the small, distinct patches of the thallus, are independent and vary in shape from flat to bullate (blister-like) or nearly stalk-like.

These areoles are typically adhered to the substrate over most of their lower surface, with the peripheral zone often free and with a maroon-purple to copper-red colour.

[2] The apothecia of Harpidium gavilaniae are irregularly rounded, typically one per areole, and immersed in the thallus, resembling those found in Aspicilia species.