Lecidella elaeochroma f. elaeochroma (images of British lichens)

Thallus a grey-white to pale-grey-green, cracked crust, usually without soredia but occasionally (f. soralifera) with small, yellow-green, spot-like soralia; apothecia small, black, concave to convex, when young with well-defined margins. An early colonist of smooth-barked trees, widespread and often very common. The thallus tests orange with sodium hypochlorite (bleach), distinguishing it from Amandinia punctata (page pending), Buellia disciformis and a few other, similar species.

Refs: Smith et al. (2009), 522; Purvis et al. (1992), 338; Dobson (2005), 239 (photo); Dobson (2011), 243 (photo); Fox et al. (2003), plate 7 (photo); Whelan (2011), 107 (photo); van Haluwyn et al. (2009), 198-9 (photo); van Herk & Aptroot (2004), 228-9 (photo); Wirth (1995), 1: 522, 525 (photo); Wirth et al. (2004), 282 (photo); Frahm et al. (2010), 54-55 (photo); Moberg & Holmåson (1984), 127 (photo); Valcárcel et al. (2003), 226-7 (photo); Thomson (1997), 396-7 (photo).

Lecidella is part of the very large 'Lecidea group' of lichens – crustose species with dark or black apothecia that lack distinct 'thalline' margins, though they will usually have differentiated 'proper' margins the same colour as the disk. Microscopic examination of mature apothecia (and sadly they are often not mature) is usually necessary even to be sure of the genus, and field identification of all but a few distinctive species is risky. Dobson (2011), pp. 236-7, gives an invaluable analysis of the component genera.

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Images of British Lichens