The type specimen was found growing on rocks in the San Gabriel Mountains of Southern California, at an elevation of 1,500 m (4,900 ft).

The lichen was formally described in a publication by American lichenologist Hermann Edward Hasse in 1897, with authorship attributed to Nylander.

This group of more or less morphologically indistinguishable species represent distinct evolutionary lineages that have diverged relatively recently.

[4] Melanohalea subolivacea has a thin, flattened, brown to olive-brown thallus that lacks isidia or soredia.

The lobes comprising the thallus measure 1–4 mm wide, and have a smooth brown lower surface that is attached to the substrate by many rhizines.