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Images of British Lichens

Psora decipiens (Hedw.) Hoffm.

Thallus consisting of yellow-brown to pink- or red-brown, variably white-pruinose, disc-like squamules, up to about 5mm diameter, with raised, white, minutely toothed margins; apothecia black with narrow, excipular margins, produced from the edges of the squamules. On bare, calcareous sand or mineral-rich soil, widespread but very local, coastal and montane.

Refs: Smith et al. (2009), 764; Purvis et al. (1992), 510; Dobson (2005), 372 (photo); Dobson (2011), 376 (photo); Jahns (1983), 208-9 (photo); Wirth (1995), 2: 786 (photo); Wirth et al. (2004), 169 (photo); Wirth, Hauck & Schulz (2013), 1: 14 (photo), 2: 947 (photo), 948; Holien & Tønsberg (2008), 186 (photo); Hansen & Andersen (1995), 109 (photo); Brodo et al. (2001), 599, 600 (photo); Thomson (1997), 506; Hinds & Hinds (2007), 423-4 (photo).

The disk-like squamules of P. decipiens could be confused with the apothecia of Psoroma hypnorum, but of course the latter has an underlying thallus of granules and occurs in non-calcareous habitats.

Psora decipiens
Psora decipiens, closer view
On open ground in dune turf over limestone, Stackpole, Pembrokeshire, May 2009. The much darker brown squamules (upper photograph) are Placidium squamulosum.

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© A.J. Silverside
Uploaded January 2012, updated September 2013