The lichen has a smooth, dull thallus varying in colour from grey to olive, with a white internal medulla.

The type specimen was collected from Monte Zerpa (Mérida at an altitude of 2,200 m (7,200 ft); there, it was found in a cloud forest.

[1] Malmidea subcinerea is a crustose lichen characterised by a continuous thallus that ranges from 80 to 120 μm in thickness.

[1] This species' photobiont is chlorococcoid, consisting of green algal cells measuring 10–12 μm in diameter.

These spores are broadly ellipsoid to fusiform, lack septate (interal partitions), with a uniformly thickened wall and a halo approximately 1 μm thick.