Description: This is a very common, bright yellow crustose species closely resembling Caloplaca citrina and at one time was included as part of that species complex. Mostly seen as a yellowy-orange powdery stain on calcareous walls, monuments and natural limestone surfaces, through a lens the powdery component will be seen to arise from the edges of minute scraps of solid thallus (areoles). It seems to be equally as common as Caloplaca citrina and occurs in similar habitats throughout Ireland. It is currently under-recorded.

Key Identification Features:

• It differs from Caloplaca citrina (described elsewhere) in having more obvious areoles that have powdery, sorediate margins, the soralia made up of smaller granules
• When fertile, the discs are not surrounded by an obviously powdery margin as in Caloplaca citrina
• The orange soredia are often much brighter than the areoles it arises from.

Original text submitted by Simon Davey

Distribution Map from NBN: Flavoplaca flavocitrina at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Flavoplaca flavocitrina at iNaturalist World Species Observations database.