[2] Found in South America, it was formally described as a new species in 2009 by lichenologists Martin Westberg, Patrik Frödén, and Mats Wedin.

The type specimen was collected by the second author from Arica (Chile), between Socoroma and Putre, at an altitude of 3,750 m (12,300 ft), where it was found growing along cracks and pits on a siliceous boulder in a dry mountain slope.

[1] Placomaronea kaernefeltii has a distinct appearance, with its thallus transitioning from a crust-like structure to one with raised edges resembling lobes.

Instead of a distinct medulla, green algae predominantly fill the interior, and the lower cortex mirrors the upper one in texture but ranges from 20 to 35 μm in thickness.

[1] The apothecia of the lichen, with a diameter ranging from 0.8 to 1.7 mm, have a flat disc that matches the bright yellow hue of the thallus.