Protoblastenia rupestris (images of British lichens)

Thallus thin, greenish, pale to orange-grey, or grey-brown, areolate; apothecia pale to deep orange, often strongly convex, not set in pits. Widespread and often common on chalk and limestone rocks, concrete, mortar of old walls and similar calcareous substrates. Resembles Caloplaca species, such as C. flavovirescens, and might well be frequently recorded as that species, but the apothecia lack thick 'proper' margins.

Refs: Smith et al. (2009), 751; Purvis et al. (1992), 501; Dobson (2005), 364 (photo); Dobson (2011), 368 (photo); Whelan (2011), 134 (photo); van Herk & Aptroot (2004), 320-1 (photo); Wirth (1995), 2: 773, 774 (photo); Wirth et al. (2004), 245 (photo); Hansen & Andersen (1995), 109 (photo); Brodo et al. (2001), 586 (photo); Thomson (1997), 502.

lastdragon.org

Images of British Lichens