The areoles, ranging from 1–2.5 mm wide, can be scattered or contiguous, sometimes aggregating to form a secondary somewhat squamulose (scaly) crust that occasionally lifts off the substrate.

[2] The apothecia are 0.3–1 mm wide, lecideine in type, and can be separate or in small groups, broadly adnate to sessile, with a black, non-powdery (epruinose), flat to weakly convex disc.

The ascospores are initially of the Callispora- or Physconia-types, then of the Buellia-type, brown, ellipsoid to broadly fusiform or bottle-shaped, measuring 13–20 by 5–7 μm, and the outer spore-wall is microrugulate.

[2] Tetramelas flindersianus has been found on hard, siliceous rocks such as quartzite at two locations on Flinders Island, Tasmania, and one in Victoria.

It is associated with typical nearshore lichen species like Buellia stellulata, Caloplaca cribrosa, Catillaria austrolittoralis, Lecanora subcoarctata, Pertusaria xanthoplaca, Rinodina blastidiata, and Tylothallia verrucosa.