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Images of British Lichens

Lecidea lithophila (Ach.) Ach.

Thallus smooth and continuous to irregularly cracked, whitish to grey or blue-grey, commonly rust-coloured in parts from deposition of iron oxides; apothecia black, usually pruinose, becoming chocolate brown when wet. On siliceous rocks and stonework, often upland, in the north and west, locally common; part of a complex of species that require chemical tests and microscopic examination for certain identification.

Refs: Smith et al. (2009), 514; Purvis et al. (1992), 332; Dobson (2005), 236, 237 (photo); Dobson (2011), 241 (photo); van Herk & Aptroot (2004, 2013), 224-225 (photo); Moberg & Holmåson (1984), 123 (photo); Wirth (1995), 1: 507 (photo); Wirth et al. (2004), 196 (photo); Wirth, Hauck & Schulz (2013), 1: 618 (photo), 639; Valcárcel et al. (2003), 224-5 (photo); Thomson (1997), 360.

Lecidea is, obviously, 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.

Lecidea lithophila
On upland boulder, Mar Estate, Aberdeenshire, April 2008

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Uploaded August 2009, last updated December 2013