The species Aspilidea myrinii was first formally described by Elias Magnus Fries, who classified it as member of the genus Parmelia.

[4] Aspilidea myrinii has a crustose thallus, which forms a crust-like layer that adheres closely to the surface it grows on (episubstratic).

The thallus is composed of small, irregularly shaped sections (areolate) and is bordered by a dark prothallus, which is a preliminary growth that outlines the main body of the lichen.

The thallus has a cortex, or outer layer, made up of elongated fungal cells arranged in a tightly packed manner (paraplectenchymatous).

[5] The apothecia (fruiting bodies) are cryptolecanorine-aspicilioid in form, meaning they have a black disc at the centre with a poorly developed thalline rim—essentially a faint, indistinct border derived from the thallus.

Chemically, Aspilidea produces norstictic and connorstictic acids, compounds commonly found in some lichen species.

This species prefers to grow on specific types of rocks, favouring crystalline schists and acidic, silica-rich stone surfaces.