Acarospora species exhibit a wide range of pigmentation e.g. (A) Acarospora sinopica (deep red-brown) intermixed with Rhizocarpon oederi (orange-red), Parys Copper Mountain, (24 March 2008) (hb NHM); (B) Acarospora smaragdula from concrete fence post adjacent to southern perimeter of unvegetated mine tailings within 500 m of Zlatna smelter, 17 July 1997. (C) Acarospora smaragdula sampled at Geevor, Cornwall, Purvis and Williamson, 1995 (Spalding et al., 1996) (D) dark brown Acarospora rugulosa Koerb. colonising brochantite (Cu4(SO4)(OH)6) secondary deposit, greenstone metamorphosed in greenschist to amphibolites facies metamorphism, Ramundberget, Härjedalen, Sweden, O.W. Purvis and R. Santesson, 18 August 1983 (hb: NHM); (E) Acarospora cf. badiofusca on weathered iron-stained schistose rocks, (collection S2_4, O.W. Purvis and B. Maltman), 16 November 2009. Colours ranged from rust-coloured in exposed situations to green in shaded crevices. [Figure 3C adapted from Figure (p. 36) (Spalding et al., 1996); Figure 3D adapted from Figure 1 (Purvis, 1984)].