The main body of these lichens, known as the thallus, is crustose, meaning it forms a crust-like appearance on the surface it inhabits.

In lichen-forming species of Arthoniaceae, the primary photosynthetic partner (the photobiont), is usually a green alga from the genus Trentepohlia.

In some genera, such as Cryptothecia and Stirtonia, the hamathecium lacks a gelatinous matrix, while in others, like Arthothelium, it is densely packed, resembling a different type of fungal reproductive structure known as ascolocular ascomata.

They come in various shapes, from club-shaped (clavate) to sac-like (saccate) or even spherical (globose), and contain a specialized cap structure (apical tholus) and an eye-like feature (ocular chamber).

The conidia (asexual spores) can vary in shape from simple, non-segmented forms to those with transverse segments, and can be oblong, rod-like (bacillar), needle-like (acicular-filiform), or sickle-shaped (falcate), and are typically hyaline.

[7] The family produces a diverse range of secondary metabolites (lichen products), including depsides, depsidones, anthraquinones, and derivatives of pulvinic acid.

[1] They are known from arctic to tropical latitudes, as well as variating altitudes from sea level to alpine regions, distributed in both humid forests and dry habitats.