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Images of British Lichens

Cystocoleus ebeneus (Dyllwyn) Thwaites

Thallus finely filamentous, like patches of lank, black hair, the hyphae seen under a microscope to be contorted, nodulose, running the length of filaments of the photobiont (algal 'partner'), Trentepohlia, and forming tight sheaths around them; apothecia unknown. Widespread but more frequent in upland areas of the north and west, on damp rock faces and on damp trunks.

Refs: Smith et al. (2009), 369 (line illustration of hyphae); Purvis et al. (1992), 229 (line illustration of hyphae), 230; Wirth (1995), 1: 367 (line illustration of hyphae), 368 (photo); Wirth, Hauck & Schulz (2013), 1: 444 (photo), 445 (line illustration of hyphae); Stenroos et al. (2011), 199 (photo); Puntillo (1996), plate 15 (photo).

This lichen requires microscopic confirmation. Racodium rupestre is macroscopically similar and also uses the orange-pigmented Trentepohlia as its photobiont, but under a microscope, the hyphal cells can be seen to be shorter and less contorted. Very useful, comparative, line illustrations are given in Smith et al., Purvis et al. and Wirth, as cited above. Regrettably the line illustration of C. ebeneus in Dobson (2005, 2011) does not portray a normal state of this species, showing neither the normal orientation of the hyphae along the length of the photobiont filament nor their contorted appearance. In my view and in my experience of demonstrating the lichen to others, the diagram causes confusion.

Ephebe lanata (page pending) is also very similar, but coarser. It uses the cyanobacterium (blue-green alga) Stigonema as its photobiont. Free-living Stigonema itself resembles Cystocoleus macroscopically, but under the microscope, Stigonema filaments (trichomes) are non-lichenised, lack orange pigment, and the cells are subspherical and commonly in more than one row.

Cystocoleus ebeneus
On damp rockface, Ty Canol, Pembrokeshire, May 2009
Cystocoleus ebeneus, photomicrograph
Cystocoleus ebeneus, photomicrograph
Cystocoleus ebeneus, photomicrograph
Cystocoleus ebeneus, photomicrograph
Photomicrographs of Cystocoleus ebeneus, from Ty Canol thalli shown above, showing hyphae wrapped along Trentepohlia filaments.
Cystocoleus ebeneus
On damp rockface, Isle of Muck, June 2012 (BLS meeting)

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© A.J. Silverside
Uploaded July 2012, last updated September 2013