Circinaria calcarea is a species of crustose lichen in the family Megasporaceae.

[2] The species has had an extensive taxonomic history, resulting in dozens of synonyms.

[1] In 2010, it was placed in its current genus, Circinaria, following molecular phylogenetic analysis of the Megasporaceae.

[3] Circinaria calcarea has a cosmopolitan distribution, having been recorded from the Arctic, Asia, Australasia, Europe, Oceania, Central America, South America, and North America.

It is a saxicolous lichen, and grows on calcareous, calciferous, and basic rock.