Montanelia disjuncta?

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chriscant
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Montanelia disjuncta?

Post by chriscant » Tue Apr 20, 2021 10:05 pm

Caz Walker and I found this lichen on a south-facing outcrop near Haweswater in Cumbria on Saturday which looks like it could be Montanelia disjuncta / Melanelia disjuncta . The only other record for Cumbria was from a BLS trip in 1979 which found it on Long Meg and her Daughters standing stones.

Medulla K- and probably KC- but very hard to do.
A thallus section showed white in UV, but it was white in the first place.

There were several thalli at one spot showing 'sorediate' clusters and virtually black on the surface. Very close by was another thallus which was 'strappier', less adpressed and more brown than black on top - and possibly had an LF on it. Both were a darker black underneath with occasional simple black rhizines. The lobes were generally shiny and convex with occasional pits, with widths starting at 0.3mm in the strappier instance. In section the thallus was white. There were some pseudocyphellae, though the soredia broke down as white, and there were fragments of other lichens mixed in.

There was some structure in the possible LF, but I couldn't find anything more in my first look - pretty hard to section.
Spot #1 overview
Spot #1 overview
Spot #1 sorediate clusters
Spot #1 sorediate clusters
Spot #1 section
Spot #1 section
Spot #1 soredia cross-section
Spot #1 soredia cross-section
Spot #1 thallus cross-section
Spot #1 thallus cross-section
Spot #2 overview
Spot #2 overview
Spot #2 close-up
Spot #2 close-up
Spot #2 shiny with rhizines and depressions
Spot #2 shiny with rhizines and depressions

Mark Powell
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Re: Montanelia disjuncta?

Post by Mark Powell » Sat May 01, 2021 10:04 am

Your lichen looks very convincingly like Montanelia disjuncta. I see this species so rarely that I don't feel justified in providing a confirmation but I wonder if you have seen the following paper?

https://www.researchgate.net/publicatio ... ral_Europe

That paper backs up some of my criticisms of the descriptions of M. disjuncta in the British literature, including the fact that it is perhaps more appropriately considered to be a sorediate lichen rather than an isidiate one. Also that the pseudocyphellae can be sparse or absent.

You may also be interested in a recent twitter thread in which a correspondent thought they might have M. disjuncta but I concluded that it was Xanthoparmelia verruculifera. The thread gave me an opportunity to discuss some of the difficulties and sources of potential confusion.
https://twitter.com/obfuscans3/status/1 ... 4313869315

Also a caution about the reliability of the N+ blue green cortical reaction in the brown Xanthoparmelia species:
https://twitter.com/obfuscans3/status/1 ... 3168159745

Mark Powell
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Re: Montanelia disjuncta?

Post by Mark Powell » Sat May 01, 2021 11:58 am

Chris mentions the difficulty of performing and interpreting spot tests and UV tests on the medulla.

Although we frequently perform spot tests in the field, such tests are much more reliable when conducted on dry specimens under a dissecting microscope. It is important to use a small amount of reagent. This is true in general and even more so for KC reactions. All too often people use a great splurge of reagent. Not only does this ruin good specimens but it tends to dilute any reaction and may also sweep substances from the medulla into the cortex and vice versa. I tend to use cocktail sticks for performing tests. This allows a very small amount of reagent to be applied accurately. I aim to moisten rather than flood the area that I intend to test.

LGBI2 gives incorrect spot reaction for the upper cortex of Parmelia sulcata. Presumably this was the result of a profligate spot test causing salazinic acid from the medulla to seep up into the cortex. Here is a twitter thread I wrote about this issue:

https://twitter.com/obfuscans3/status/1 ... 9338936321
EM3wcsRWoAE1v0M.jpeg
EM3wcsRWoAE1v0M.jpeg (12.8 KiB) Viewed 809 times
Interpreting fluorescence of white lichen tissue is difficult because the reflection of visible light can be confused with fluorescence. I tend to use a specimen of something similar but that I know to be non-fluorescent to compare with the specimen I am testing. For example, if I suspect that I have Cladonia glauca, it is useful to also have a specimen of a non-fluorescent Cladonia for comparison. The medulla of both is exposed and the bright white fluorescence of C. glauca can be distinguished from the whitish reflection of non-fluorescent species.

Caz Walker
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Re: Montanelia disjuncta?

Post by Caz Walker » Tue May 04, 2021 9:39 pm

Thanks very much Mark. It's always good to have a supportive reply especially with the added info you provide. The M disjuncta we saw certainly looked sorediate rather than isidiate and pseudocyphellae weren't obvious.

Brian C and John Douglass have confirmed our tentative ID from the photos so, with your input as well, we're happy about submitting the record.

Caz

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