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Hypotrachyna revoluta (Flörke) Hale
 
(= Parmelia revoluta Flörke)


Thallus foliose, light grey, lobes smooth and often lustrous above, edges turned down and tinged tan-brown, soralia with pale grey to green, powdery soredia, ± terminal to diffusely scattered on surfaces of lobe tips, initially not sharply delimited, affected lobes becoming strongly revolute and often becoming erect, undersurface pale to dark brown, rhizines simple or some or many branched; apothecia rare. Evidently widespread but predominantly in southern and western Britain, mainly on branches of deciduous trees, rarely saxicolous; much confused with H. afrorevoluta, which has only recently become understood and may be the commoner species.

Refs: Smith et al. (2009), 441; Purvis et al. (1992), 430 (as Parmelia); van Haluwyn et al. (2009), 96-7 (photo); Wirth (1995), 2: 646, 649 (photo, as Parmelia); Holien & Tønsberg (2008), 51 (photo); Nordic Lichen Flora (2011) 4: 63, 157 (photo, printed too dark); Thor & Arvidsson (1999), 194, 274 (photo); Arup et al. (1997), 181 (photo); Lichen Atlas of the British Isles 1: 1008 (1995) (as Parmelia; includes H. afrorevoluta).

H. afrorevoluta differs in its initially pustulate, marginal and laminal, greyer and coarser soredia, and apparently in its darker undersurface. Hinds & Hinds (2007) and Elix & Thell in Nordic Lichen Flora (2011) give useful descriptions of both species, and van Haluwyn et al. (2009) provide a valuable photographic comparison. The photo in Van Herk & Aptroot (2004, 2013), 194-195, most likely depicts H. afrorevoluta

Hypotrachyna revoluta
Hypotrachyna revoluta
Hypotrachyna revoluta, closer view
Hypotrachyna revoluta, dry
On branches of Hawthorn (Crataegus monogyna) on loch edge, Castle Semple Loch, Renfrewshire, December 2011.


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© A.J. Silverside
Uploaded April 2008, page revision (new photographs) December 2011. last updated December 2013