Bilimbia sabuletorum (images of British lichens)

Thallus a thin, granular, whitish-grey crust; apothecia brown, strongly convex. Widespread and common, growing over mosses and plant debris on calcareous walls and nutrient-rich bark.

Refs: Smith et al. (2009), 219; Purvis et al. (1992), 114 (as Bacidia sabuletorum); Dobson (2005), 277 (photo, as Myxobilimbia); Dobson (2011), 91 (photo); van Herk & Aptroot (2004, 2013), 256-7 (photo, as Myxobilimbia); Wirth (1995), 2: 596 (photo, as Mycobilimbia sabuletorum); Brodo et al. (2001), 172 (photo, as Bacidia sabuletorum); Thomson (1997), 423 (as Mycobilimbia sabuletorum).

Bacidia bagliettoana occurs in similar habitats, differing in its black, ± flat apothecia and different spores.

lastdragon.org

Images of British Lichens