• Caloplaca dichroa Arup 
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Caloplaca dichroa
© Mike Simms
Caloplaca dichroa
© Mike Simms

There are no records for this species at present.


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Formerly subsumed under the heading of Caloplaca citrina agg., this species is a familiar sight on calcareous walls, mortar and limestone rock. The body of the lichen is visible as a granular orange crust cracked into islands (areoles) of thallus. Discs are common with spores thick-walled when young. There is a yellow colour form and occasionally the two forms occur side by side. The very small granules (blastidia) are sparingly sorediate. In Ireland, this species is probably widely under-recorded.

Key characteristics

  • Thallus: small, minutely granular orange or yellow, cracked into areoles
  • The tiny blastidia slowly break down into soredia; internally, the spores show hourglass configuration.

Original text submitted by Vince J. Giavarini

 Simms, M. J., (2016). Caloplaca dichroa Arup . [In] LichenIreland. Accessed on 2018-07-19.