Lichens of Wales

Sticta canariensis

<em>Sticta canariensis</em>

Sticta canariensis

Description & Identification

Whilst most lichen-forming fungi form an association with just one species of alga or cyanobacterium a few form a lichenised partnership with more than one. When one algal partner is a green alga and the other a cyanobacterium it is perhaps not surprising that the resultant lichens can look very different from one another. So great can be this difference that they have been given different scientific names.This unfortunately breaches the widely accepted convention that the name of a lichen is the name of its fungus since the fungi are considered to never be able to complete their life cycle without the algae or cyanobacteria whilst the algae and cyanobacteria are still capable of an entirely independent existence and so have their own names.

Photo: Liz Fleming-Williams Photo: Ray Woods



Once it was established that the same fungus was involved with two different photosynthesising partners a decision had to be made as which of the two names should be used.  The name Sticta dufourii had been applied for many years to the lichen with cyanobacteria as a photobiont and Sticta canariensis to the same fungus having a green alga as a photobiont.  The latter name was adopted. So S. dufourii became S. canariensis cyanobacterial morph (or morphotype or photomorph) and S. canariensis became S.  canariensis green algal morph (or morphotype or photomorph). The cyanobacterial morphotype is much more common in Britain and Wales than the green algal morphotype. Occasionally the green morph can be found growing out from the edges of the lobes of the cyanobacterial morph and very very rarely can the green algal morph be found growing on its own.

Section 42 lists only the green algal containing morphotype as being in need of special protection. Woods & Coppins (2003) specifically evaluate the green morph stage only when it is independent of the cyanobacterial morph. This independence is not specified in Sect 42. This is perhaps just as well as few records of the green morph specify whether they were free living or growing on the cyanobacterial morph. It is probable that in Wales the green algal morphotype only occurs growing at least initially on the edge of the thallus lobes of the cyanobacterial morphotype (see photo below).

They may subsequently fix themselves independently to the rock or adjacent moss colonies.   From a distance the grass-green lobes of the green algal morphotype when well developed (up to 1.5cm wide and 10cm long though usually much smaller) look like a form of endive. If you find a grass-green (when wet) or grey-green (when dry) foliose lichen sprouting out from the edges of the much darker coloured lobes of what appears to be a totally different and much darker coloured lichen with its lobe margins shredded into branched isidia on rocks in a shaded, damp ravine you will have probably located this species but you must check the underside of the lobes. Don’t pull a bit off but carefully fold a lobe back, wetting it first if it’s dry. As with all Sticta species the undersides of the lobes should be covered in a short dense felt of rhizines with small circular bald patches-the cyphellae scattered here and there. If what you find are long shaggy rhizines sprouting from raised ridges you will have found a species of Peltigera. Members of this genus occasionally develop green algal containing morphs along the margins of their thalli though I am not aware of any records of this happening in Wales. The green algal morph has no special reproductive structures since isidia are absent and it has never been observed with apothecia in Wales. (RGW)
NBN Taxon Key