While morphologically similar in some aspects, the species can be distinguished by their lobe shapes, cortex cell sizes, medulla structure, and distinct secondary metabolite compositions, with H. deusta producing fumarprotocetraric acid as its major compound and H. lugubris containing alectorialic acid as its primary metabolite.

This relationship is further supported by their similar spore morphology, with both species producing bacilliform (rod-shaped) conidia.

The two species in the genus form different shapes: H. deusta produces strap-like growths up to 1 cm tall with slight channels, while H. lugubris forms larger growths up to 4 cm tall that range from awl-shaped to strap-like structures.

The species also differ in where they house their symbiotic algae – in H. deusta, the algal cells are found beneath reproductive structures (pycnidia and apothecia), while in H. lugubris they occur in light-coloured patches below the cortex.

[5] Both species reproduce mainly through apothecia (fruiting bodies), which typically form on the surface of the lichen.

H. deusta occurs in Tierra del Fuego near Cape Horn, Chile (approximately 56°30'S, 60°W) and the Falkland Islands.