[1] The genus was circumscribed in 1803 by Swedish lichenologist Erik Acharius, with Bathelium mastoideum assigned as the type species.

[2] Genus Bathelium features a corticate thallus (a protective outer layer) usually with olive-green to brownish or greyish hues.

This genus is distinguished by the form of its ascomata, the spore-producing structures, which possess apical ostioles (openings at the top).

They are noticeable, ranging from prominent to sessile, and show a brown-black colouration, though in rare instances, they may have a whitish pruinose (powdery) appearance.

These spores are fusiform, meaning they have a spindle-like shape, with either acute (pointed) or rounded ends, and are not constricted at the median septum.