Caloplaca lucifuga (images of British lichens)

A minute and inconspicuous species with a thin, grey, filmy thallus that may be immersed in the bark surface, and tiny, usually crowded, rounded, yellow to orange-brown soralia, which test purple with potassium hydroxide; apothecia unknown. An apparently rare species in crevices of rough bark of mature trees, most usualy Oak (Quercus); known from scattered localities in the north and west; first described as a species in 1988 and no doubt overlooked.

Refs: Smith et al. (2009), 266; Purvis et al. (1992), 154; Thor & Arvidsson (1999), 242 (photo); Lichen Atlas of the British Isles 6: 1642 (2001).

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Images of British Lichens