Melanelixia subaurifera (images of British lichens)

Thallus green to dull brown, matt to moderately shiny, surface with sparse to clustered punctate soralia and soft, globose isidia about 0.2mm (to 0.4mm) in height, leaving creamy white or yellow scars when rubbed off, medulla and soralia giving positive pink to red reaction with bleach (sodium hypochlorite); apothecia rare. On trees, especially the smaller branches and twigs, rarely rocks, generally common throughout Britain.

Refs: Smith et al. (2009), 572; Purvis et al. (1992), 433 (as Parmelia); Dobson (2005), 264 (photo, as Melanelia); Dobson (2011), 268 (photo); Jahns (1983), 200-1 (photo, as Parmelia); Whelan (2011), 115 (photo); van Haluwyn et al. (2009), 62-3 (photo); van Herk & Aptroot (2004), 246-247 (photo, as Melanelia); Nordic Lichen Flora (2011) 4: 75, 160 (photo, printed too dark); Wirth (1995), 2: 642, 657 (photo, as Parmelia); Frahm et al. (2010), 116 (photo); Puntillo (1996), plate 29 (photo, as Parmelia); Hinds & Hinds (2007), 319-320 (photo, as Melanelia) (recommended reference); Brodo et al. (2001), 439-440 (photo, as Melanelia); Walewski (2007), 112 (photo, as Melanelia); McCune & Geiser (2009), 199 (photo); Lichen Atlas of the British Isles 1: 1020 (1995) (as Parmelia).

Closely similar is M. glabratula (q.v.), with which it often grows. Several Melanohalea species are also similar, but are C- (i.e. no bleach reaction).

lastdragon.org

Images of British Lichens