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Images of British Lichens

Sticta canariensis (Flörke) Delise
(= S. dufourii Delise)

Cyanobcterial morph: thallus foliose, lobes thin, overlapping, marbled pale grey to grey-brown, darker dull brown when moist, margins rounded to dissected, surface and margins beset with tiny, dissected folioles or flattened, branched isidia, thallus sometimes with bright green, attached, single lobes of the green-algal morph, underside pale-tomentose with scattered, white cyphellae.; apothecia unknown. Green-algal morph: when occurring as independent thalli, lobes green, elongated and dichotomously branched, without folioles/isidia, not unlike a thallose liverwort but underside with cyphellae; apothecia red-brown, rare.
Generally amongst rocks in moist, sheltered, shaded situations, confined to the oceanic west, the free-living, green-algal morph much rarer than the cyanobacterial morph.

Refs: Smith et al. (2009), 866; Purvis et al. (1992), 583; Dobson (2005), 418-99 (photos, cyanobacterial morph + attached lobes of green-algal morph); Dobson (2011), 423-44 (photos, cyanobacterial morph + attached lobes of green-algal morph); Whelan (2011), 142 (photos, cyanobacterial morph, as S. "deflourii", + green-algal morph as inset); Jahns (1983), 242-3 (photo, ?green-algal morph, dry, atypical); Puntillo (1996), plate 38 (photo, cyanobacterial morph); Nordic Lichen Flora (2007) 3: 84, 207 (photo, cyanobacterial morph); Lichen Atlas of the British Isles 3: 1365, 1366 (1998).

This lichen is noteworthy in that the algal component (photobiont) may be a cyanobacterium or a green alga (Chlorophyta), and that the morphology of the lichen is markedly affected by which of the photobionts is present. In the past, the name S. canariensis was applied to the green-algal morph and the cyanobacterial morph was treated as a separate species, as S. dufourii. However, the Latin name of the lichen is strictly that of the fungal component (mycobiont) and is not affected by the identity of the photobiont. Consequently, the name "S. dufourii" is merely a synonym of S. canariensis. It displays a degree of misunderstanding of the naming of lichens even to refer informally to the "canariensis morph" and the "dufourii morph", better to refer to them as the green-algal and cyanobacterial morphs, as done here.

Sticta canariensis, cyanobacterial morph
Cyanobacterial morph in rather dry state (darker when moist): on damp, sheltered cliff-face, Bàgh a Ghallanaich, Isle of Muck, June 2012 (BLS meeting)
Sticta canariensis, cyanobacterial and geen-algal morphs
Sticta canariensis, cyanobacterial and geen-algal morphs, close view
Cyanobacterial morph, very wet, partly moribund and mixed with leafy liverworts, with scattered, attached, bright yellow-green lobes of the green-algal morph:
on sheltered, wet, coastal rocks near Port Mòr, Isle of Muck, July 2012 (BLS meeting)

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© A.J. Silverside
Uploaded October 2013