Protopannaria species form a small, often overlapping mosaic of scales that ranges from crust-like patches to more distinct . These units are usually anchored by a blue to blue-black fibrous layer () that can be visible at the margins. The upper surface varies from greyish blue to deep brown-black and lacks a differentiated . The fungal
hyphae weave among the cells of a blue-green
cyanobacterial partner (
Nostoc), creating a loose to texture beneath the surface. The fruiting bodies (
apothecia) bear red-brown to nearly black and retain a persistent rim of thallus tissue (a ). This margin is two-layered: its outer zone consists of tightly packed pseudoparenchymatous cells, while the inner zone is looser and densely infused with cells. A pale, thin surrounds the
hymenium. When treated with iodine, the hymenium
stains blackish blue (I+). Each
asci produces eight
ascospores and belongs to the
Pannaria structural type, lacking any
amyloid apical apparatus. The spores are colourless, single-celled and
ellipsoidal, often ending in one or two pointed tips and carrying a finely warted outer layer.
Asexual reproduction occurs in immersed
pycnidia that release straight, rod-shaped
conidia. No
secondary metabolites (
lichen substances) have been detected in the genus by
thin-layer chromatography. ==Ecology==