The genus is characterized by a pored or fenestrate epicortex (a thin homogeneous polysaccharide layer on the surface of the cortex), and the production of lecanoric acid as the primary chemical constituent of the medulla.

The genus name combines Melanelia with the name of lichenologist John A. Elix, "for his immense contributions to lichen systematics and chemistry, especially in Parmeliaceae.

The upper surface of the thallus ranges in colour from olive-green to dark brown, and has a smooth or wrinkled texture.

Features that are variably present on the thallus include maculae (spots or stains), soredia, isidia, and cortical hairs.

[1] Lichens in the genus Pleurosticta are similar in appearance, but are distinguished from Melanelixia by their broader lobes, pores on the epicortex that are reticulated, a pigment that reacts violet in K and HNO3, and the presence of depsidones in the medulla.