[1] Found in Tasmania, it was formally described as a new species in 2018 by lichenologists Gintaras Kantvilas, Eimy Rivas Plata, and Robert Lücking.

The type specimen was collected by the first author near Little Fisher River at an altitude of 820 m (2,690 ft), where it was found in a cool temperate rainforest growing on Atherosperma moschatum.

[3] Coenogonium atherospermatis has a crusty, pale greenish to yellowish-grey thallus that forms irregular patches up to 30 mm (1.2 in) wide.

The photobiont cells are more or less spherical, broadly ellipsoid to oblong, and occur in clumps or short chains.

The apothecia, or fruiting bodies, are sessile and flat, with a yellowish-beige disc that is usually plane but may be slightly convex when old.