Grizzled and Cracked

 Fencepost of the Week #251

 

 

Cavernous Crater at Dusk

 Fencepost of the Week #250

 

 

Ricasolia virens - Cyanomorph, Chloromorph and Photosymbiodeme

Some lichenised fungi are capable of associating with both cyanobacteria and algae as photosynthetic partners. In some cases the appearance of the lichen changes very dramatically depending on which photobiont is present.

Ricasolia virens - cyanomorph

For example, here is Ricasolia virens - a small, bushy, cushion-forming jelly lichen. A cyanobacterium is the photobiont here.

But... This is also Ricasolia virens - a large, strikingly green, foliose lichen. This one has an alga as the photobiont:

Ricasolia virens - chloromorph

You can call the cyanobacterium containing lichen a cyanomorph and the alga containing lichen a chloromorph. 

Sometimes you will find a lichen with both photobionts on the same thallus - this can be called a photosymbiodeme. Here is a Ricasolia virens photosymbiodeme:

Ricasolia virens - photosymbiodeme

Related phenomena occur with Sticta canariensis and Ricasolia amplissima.

Sticta canariensis - photosymbiodeme

Ricasolia amplissima - photosymbiodeme

A slight complication: the word cephalodium can also be used to describe a lichen with algae and cyanobacteria both present, but it only allows for cases where the cyanobacteria are kept in small, subsidiary structures within or budding off of a primary chloromorphic thallus.

You can read much more about Ricasolia virens and its forms in this 2016 paper: 
The cyanomorph of Ricasolia virens comb. nov. (Lobariaceae, lichenized Ascomycetes)
By
Tønsberg, Blom, Goffinet, Holtan-Hartwig & Lindblom 
https://doi.org/10.5962/p.386096

Diversity in Black and Green

 Fencepost of the Week #249

 A beguiling assemblage of lichens on this post betwixt field and forest.

 

Crowned in Sticta

 Fencepost of the Week #248

 Sticta sylvatica thriving in a damp, shady corner of the paddock.

 

Bilberry Webs

 Fencepost of the Week #247

 

Minutely Fruticose Jelly Lichens

 Trying to make sense of some superficially minutely fruticose, corticolous jelly lichens in Cowal. 

Working primarily from the BLS Lichens of Great Britain and Ireland 3 pdfs

 

Row 1 entire organism

Row 2 surface structure (width ~3mm)

Row 3 cross section from near substrate (bottom left) to surface (top right)

Row 4  cells of the cortex (width ~150µm)

Column 1: this is Scytinium lichenoides with well developed isidia, I think. 

Column 2: also S. lichenoides. The isidia are so thick that the foliose thallus in completely hidden. But proves to be structurally similar when cut open.

Column 3: Ricasolia virens cyanomorph

Column 4: Ricasolia amplissima cephalodium

I've just found a paper describing a cyanomorph of Ricasolia virens. Column 3 conforms very closely to the description given here: The cyanomorph of Ricasolia virens comb. nov. (Lobariaceae, lichenized Ascomycetes) DOI: 10.5962/p.386096