ASCOMYCOTA | LECANOROMYCETES > TELOSCHISTALES > Teloschistacae

Genus Caloplaca, meaning 'beautiful patches'

Common name:            -

Synonym:                      Caloplaca caesiorufa

Habitat:                          Coastal

Substrata:                      Rock

Growth form:                Saxicolous    

Thallus:                 Crustose

Apothecia:                    Lecideine

BLS identity rating:        Graded 2/5 (see note)

Thallus areolate, often with a roughened surface, typically pale grey in colour and growing to around 5cm diameter; prothallus inconspicuous or absent; apothecia can be numerous and crowded; discs rounded or distorted, flat or very slightly convex, normally bright orangish, sometimes more rusty orange, but turning greenish when wet; the matt margins are paler, almost white on the underside.

A coastal, somewhat variable species dependent on habitat. Normally found on shaded siliceous rocks in the upper supralittoral zone. It is most likely to be confused with Caloplaca crenularia, which can occur on the coast as well as inland, but that species has apothecia that remain orange when wet and have shiny rather than matt margins.

Experienced lichenologists will probably be able to recognise the species on sight, but unless a water test has confirmed the colour change, microscopic examination is recommended to confirm identity.