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Hypotrachyna afrorevoluta (Krog & Swinscow) Krog & Swinscow
 
(= Parmelia afrorevoluta Krog & Swinscow)


Thallus foliose, light grey, lobes smooth and often slightly lustrous above, to matt with surface very minutely rugulose, edges turned down and tinged tan-brown, soredia initially pustulate, marginal and laminal, with rather coarse, grey-green to dark grey soredia (green when wet), undersurface black, brown at margins, rhizines unbranched or some bifurcate, occasionally projecting horizontally as cilia from lobe margins; apothecia rare. Widespread and evidently frequent but under-recorded, on trunks and main branches of deciduous trees; only recently distinguished from H. revoluta.

Refs: Nordic Lichen Flora (2011) 4: 62, 157 (photo, printed too dark); Smith et al. (2009), 441 (briefly, under H. revoluta); Purvis et al. (1992), 430 (as Parmelia, briefly, under P. revoluta); Dobson (2011), 198 (photo); van Haluwyn et al. (2009), 96-7 (photo); Wirth, Hauck & Schulz (2013), 1: 536 (photo), 2: 808; Frahm et al. (2010), 110-11 (photo); Hinds & Valcárcel et al. (2003), 276-7 (photo, as Parmelia revoluta); Hinds (2007), 277.

H. revoluta differs in its green soralia on the tips of terminal lobes, with finer soredia, and pale to darkish brown 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. Correct placement of some specimens is difficult, but they seem distinct when growing in proximity, H. afrorevoluta on trunks and main branches, H. revoluta favouring smaller branches.

I first encountered this species in 2009 (photographs below), at a time when the BLS website considered British records to be erroneous, but it was immediately apparent that this was not H. revoluta as I knew it. Instead it matched continental internet pictures of H. afrorevoluta. The species is now generally accepted. Elix & Thell consider it more coastal than H. revoluta in Scandinavia.

FGBI: http://fungi.myspecies.info/all-fungi/hypotrachyna-afrorevoluta

Hypotrachyna afrorevoluta
On trunk of hybrid Sallow (Salix x multinervis), Gleniffer Braes, Renfrewshire, April 2011
 
Hypotrachyna afrorevoluta
Hypotrachyna afrorevoluta
On trunk of Crack Willow (Salix fragilis) in damp woodland, Shewalton Sand Pits, Ayrshire, May 2009 (with the orange alga, Trentepohlia)
 
Hypotrachyna afrorevoluta
Hypotrachyna afrorevoluta
On trunk of Norway Maple (Acer plananoides) in town centre, Paisley, Renfrewshire, November 2011
 
Hypotrachyna afrorevoluta
On trunk of Oak (Quercus robur), lobes and soredia green, as wet from melted snow, Wicken Fen, Cambridgeshire, February 2010


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© A.J. Silverside
Uploaded December 2011, updated January 2016