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Images of British Lichens

Dirina massiliensis (Schreb.) Norman
f. sorediata (Müll. Arg.) Tehler
(incl. Dirina stenhammarii (Arnold) Poelt & Follmann)

Thallus variable, typically rounded with a delimited and sometimes zoned margin, generally rather thick, with convex areoles, grey to chalky white, scratching yellow-orange (Trentepohlia photobiont), sorediate in f. sorediata, the soralia grey to grey-brown, initially delimited but coalescing in the centre of the thallus; apothecia present only in f. massiliensis, grey, pruinose. Widespread, especially on basic rocks, but evidently more common in the south-east, developing the thick, chalk-like thallus on hard limestones (Smith et al., 2009). The f. massiliensis is much rarer and said to occur mainly on vertical faces of hard limestones near the coast.
Lecanora pannonica (page pending) can look similar and may occur with D. massiliensis.It has bluish soredia, oten with a 'metallic' appearance, and does not scratch orange.

Refs: Tehler, et al. (2013), Lichenologist 45: 456-9; Smith et al. (2009), 383; Purvis et al. (1992), 239; Dobson (2005), 168-9 (photo, both forms); Dobson (2011), 174 (photo, both forms); van Herk & Aptroot (2004, 2013), 176-177 (photo, f. sorediata, as species); Wirth (1995), 1: 381 (photo, f. sorediata, as D. 'stenhammari'); Wirth, Hauck & Schulz (2013), 1: 462 (photo, f. sorediata, as D. stenhammarii); Puntillo (1996), plates 16,17 (photos, incl. f. sorediata).

Recent revision (Tehler, et al. (2013), Lichenologist 45: 427-476) has shown that the taxon on base-poor rocks, with a thinner, more diffuse thallus with a generally grey-brownish cortex, is a separate species, D. fallax. Distribution in Britain not yet known but it is at least in the south-west. Like D. massiliensis It also occurs as sorediate and fertile morphs.

Dirina massiliensis
Church wall, Littlebury, Essex, July 2009. Note orange colour where scratched.
Dirina massiliensis
Church wall, Crostwick, Norfolk, April 2010.
Dirina massiliensis, close view
Dirina massiliensis
On limestone church wall, Holme next the Sea, Norfolk, April 2010, thick, chalk-like variant of limestone rocks (cf. Wirth (1995), 381).

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© A.J. Silverside
Uploaded August 2009, revised and extended November 2011, last updated January 2016