[1] Found in Brazil, this species is notable for its dark carmine-red thallus and its known as ascomata (fruiting bodies), which are grouped in clusters of 5–30.

[2] The type specimen of Pyrenula cinnabarina was collected from Catimbau National Park in Buíque, Pernambuco, Brazil, at an elevation of about 880 m (2,890 ft).

The ascomata are superficial (situated on the surface), globose (roughly spherical), 0.2–0.35 mm in diameter, and clustered in groups with fused walls but separate ostioles (openings).

The ascospores are brown, arranged in a single row within the asci, and have diamond-shaped internal cavities separated from the wall by a thick layer.

It is closely related to Pyrenula reginae, which grows in the same area, but differs mainly in that its hamathecium is inspersed (contains oil droplets).