Acarospora fuscata (images of British lichens)

Thallus consisting of interlocking, angular, brown areoles (sometimes overlapping to become subsquamulose), testing red with sodium hypochlorite (bleach), areolar margins often slightly raised and (as aptly described by Dobson) giving the thallus the appearance of dried, cracking splashes of mud; apothecia one or more per areole, darker, immersed, irregular in shape. Widespread and common on silicious but nutrient-enriched rocks and stonework.

Refs: Smith et al. (2009), 128; Purvis et al. (1992), 60; Dobson (2005), 62 (photo); Dobson (2011), 56-7 (photo); Whelan (2011), 44 (photo); van Herk & Aptroot (2004), 46-7 (photo); Wirth (1995), 1: 105 (photo); Wirth et al. (2004), 230 (photo); Moberg & Holmåson (1984), 164 (photo); Pope (2005), 58 (photo); Thomson (1997), 23, 24 (photo); Brodo et al. (2001), 146 (photo).

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Images of British Lichens