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 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.