Fencepost of the Week #249
A beguiling assemblage of lichens on this post betwixt field and forest.
Welcome to Wildeep's Illuminations, a blog of imagery and rumination, fresh from the desktop of Ben Mitchell.
Trying to make sense of some superficially minutely fruticose, corticolous jelly lichens in Cowal.
Working primarily from bls lichenology 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 very well developed isidia, I think.
Column 4: Ricasolia amplissima cephalodium
I did think that Column 2 and 3 were Scytinium pulvinatum and Scytinium teretiusculum respectively.
Recently column 2 has been identified on iNaturalist as Scytinium teretiusculum, which is leading me to think that column 3 might be the cyanobacterial morphotype of Ricasolia amplissima.
Reasons to think Col 3 is R. amplissima:
- cells of the cortex are arranged loosely into courses, giving the surface a grain, a trait shared with Col 4.
- no primary, foliose thallus detected. Fruticose all the way down. (S. teretiusculum should have foliose lobes as a base)
Reasons to think Col 3 is not R. amplissima:
- differs from R. amplissima cephalodia in branching structure, shape and colour. The few photos of cyanobacterial R. amplissima I have found online resemble Col 4 more than Col 3. afl-lichenologie.fr has some.
- differs in habitat and distribution; algal morphotype of R. amplissima mostly on trunks of mature parkland trees; Col 3 is mostly on small, scrubby willows (6 locations) also seen once on an oak branch and once on a hazel stem.
I have not seen Col 3 in close association with R. amplissima locally. However, on a LNHG field trip in February I did see one small R. amplissima thallus on a young willow with Col 3 present in the same stand of trees.
Edit: from further discussion on iNaturalist, Column 3 has now been confirmed as Scytinium teretiusculum with column 2 likely being Scytinium lichenoides - same species as column 1.
S. pulvinatum is mainly saxicolous. I hope to do a similar treatment to the above as a way of differentiating it from saxicolous S. lichenoides.
Aim: to track changes in lichen & bryophyte coverage on several boulders in the Glenan nature reserve over the years.
We propose to use photogrammetry to scan selected rocks anually; successive scans will be combined to produce 2d / 3d animations depicting the changes in vegetation cover over time.
Meet the rocks:
Archie: One of the few places on the reserve where Ricasolia virens grows. Also with some Lobarina scrobiculata mixed in.
Brad: Right next to the path, just inside the woods. Brad has Nephroma laveigatum and patchy moss coverage. A small holly tree stands beside them, and there is a substantial void beneath.
Doug: well up in a jumble of coarse talus, Doug is multifaceted - including some overhaging surfaces.
Ivor: has a good variety of bryophytes - including some haircap moss, but also some small tufts of grass showing. Perhaps Ivor is on their way to becoming turfed over?
3d scan of Frank embedded in a webpage: