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Images of British Lichens

Aspicilia cinerea (L.) Körb.
(sensu stricto)

Thallus a light grey crust, cracking into irregular areoles, testing red with KOH; apothecia initially set in the thallus, becoming sessile, with black discs and conspicuous white margins, one or more per areole, mature ascospores 12-22×6-13µm (measurements from Fletcher et al., in Smith et al., 2009), pycnidia, tiny, black, dotting the thallus surface, producing conidia 11-16×1µm. On siliceous rocks, perhaps mainly in the north and west, but distribution uncertain due to confusion wih related species.

Refs: Smith et al. (2009), 184; Purvis et al. (1992), 99; Dobson (2005), 73; Dobson (2011), 80; Wirth (1995), 1: 148, 151 (photo); Stenroos et al. (2011) 62-3 (photos); Valcárcel et al. (2003), 120-1 (photo); Brodo et al. (2001), 168 (photo).

It appears that the majority of British records for this species actually relate to the closely similar A. intermutans. The latter is distinguished by its larger mature ascospores, (20-)22-28×(11-)12-14µm, and smaller conidia, 7-11×1µm. The photographed material was identified by its large conidia (easily obtained by scraping pycnidia from the thallus surface and examining the broken pycnidia under a microscope, measuring the emerging conidia).

Aspicilia cinerea
Aspicilia cinerea, close view
                                             On stone memorial, Ardclach, Morayshire, August 2010 (BLS meeting), identified on size of conidia;
                                                  upper photograph shows thallus margin, dotted with pycnidia and young apothecia;
                                                  lower photograph (closer view) shows apothecia from the centre of the thallus.

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© A.J. Silverside
Uploaded March 2011, last updated August 2013