This is a phylogenetically defined group of lichens featuring an erect foliose to subfruticose thallus with reproductive structures, both sexual (apothecia) and asexual (pycnidia) located on the margins of lobes.

[10] Some earlier studies suggested that while Melanelia stygia was closely aligned with the cetrarioid clade, it should not be considered a true member of this group.

In Finnish, it is called sysiruskokarve, meaning "sooty brown lichen," while the Icelandic name bikdumba translates to "pitch-dark" or "tar-dark".

Under magnification, one can observe tiny dark brown dots called pseudocyphellae scattered across the surface, each surrounded by a slightly raised rim.

The lower surface shares a similar dark colouration and displays a wrinkled texture, anchored by thick, mostly unbranched root-like structures called rhizines.

These disc-like structures start concave when young but flatten or become convex as they mature, maintaining a dark brown colour and glossy appearance.

The inner layer (medulla) typically shows an orange-red reaction when tested with para-phenylenediamine (Pd) due to the presence of fumarprotocetraric acid.

This growth rate is notably slower than most other parmelioid lichens, likely an adaptation to the harsh conditions of its alpine and arctic habitats where the growing season is limited by persistent snow cover and low temperatures.

Melanelia hepatizon can be distinguished by several features: its reproductive structures (both apothecia and pycnidia) occur primarily along the margins rather than across the surface, and its pseudocyphellae are predominantly found at the edges.

Additionally, when tested with potassium hydroxide (K), its inner layer turns yellow due to the presence of stictic and norstictic acids, unlike M. stygia.

Pseudephebe minuscula shares the dark brown, glossy appearance and arctic-alpine habitat preference, but can be distinguished by its consistently narrower branches and the absence of true pseudocyphellae, though it does have pits from sunken pycnidia that can superficially resemble them.

Its ability to grow in both extremely cold arctic environments and high-altitude alpine regions suggests a tolerance for harsh climatic conditions.

Like other species restricted to open habitats in boreal, alpine and Arctic zones, M. stygia is predicted to respond negatively to warming temperatures and associated vegetation changes, though its specific responses to these environmental shifts remain largely unknown.

However, in its alpine habitats, it may benefit from increased moisture availability through frequent rain, mist and fog, which allows for extended periods of metabolic activity when conditions are suitable.