K/UV reaction

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Dave Lamacraft
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K/UV reaction

Post by Dave Lamacraft » Mon Mar 16, 2020 6:15 pm

Hi,

I'm sure the answer to this is already lurking somewhere in this forum, but I can't find it, so.....

Can someone remind me what a strong K/UV yellow reaction is telling me? In this case there was a weak yellowish K reaction before UV turned it into that amazing bright yellow.

Thanks!

Dave

Neil Sanderson
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Re: K/UV reaction

Post by Neil Sanderson » Mon Mar 16, 2020 7:56 pm

Dave

The K/UV + bright neon yellow spot test is a good indication of atanorin, especially if the spot test gives the best results when dry. Not tested to exhaustion, so use with caution. Fine if you expect atanorin, but other K spot tests can be enhanced by UV too.

Neil
Neil Sanderson

janetsimkin
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Re: K/UV reaction

Post by janetsimkin » Mon Mar 16, 2020 8:36 pm

Could someone (Neil?) produce a short summary of these K/UV reactions and what they tell us that we could put on the BLS website?
Alright, I admit it - I need it! If incomplete we can always update it later.
Janet

Mark Powell
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Re: K/UV reaction

Post by Mark Powell » Mon Mar 16, 2020 9:54 pm

I wrote a fair summary in the Bulletin and scans of this have been posted on my twitter:
https://twitter.com/obfuscans3/status/1 ... 9828069376
If you need further information, then do let me know.
So far, it is still the atranorin and confluentic acid tests that have proved potentially useful (though I suspect that there are others to be discovered).
The K/UV of atranorin is useful to confirm (or dismiss) low concentrations in e.g. Cladonia rangiformis and the medulla of Physcia aipolia.

Mark Powell
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Re: K/UV reaction

Post by Mark Powell » Mon Mar 16, 2020 9:56 pm

When you click on my twitter link (previous post), you will need to scroll down the thread to see the scans of the Bulletin article detailing the K/UV reactions.

Mark Powell
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Re: K/UV reaction

Post by Mark Powell » Mon Mar 16, 2020 10:10 pm

I have just dug out my scans which I can attach here (you may still like to go and browse my twitter 8-) ).
The first (and so far only) formal publication of K/UV reactions was:
Powell, M. (2018) Spot tests and staining: some recent advances. Bull. Brit. Lichen Soc. 123: 77-82.
[The Winter 2018 edition of 'The Bulletin']
Attachments
kuv1.jpg
kuv2.jpg

janetsimkin
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Re: K/UV reaction

Post by janetsimkin » Mon Mar 16, 2020 10:14 pm

Sorry Mark, I must have missed this. Will sort something out for the website.
Janet

Dave Lamacraft
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Re: K/UV reaction

Post by Dave Lamacraft » Tue Mar 17, 2020 12:08 pm

Thanks all. That makes sense, the specimen in question was a supposed Lecanora alboflavida that was a bit chewed and with a not overly convincing C+ reaction, so guessing the K/UV neon yellow helps confirm that.

Thanks again, Dave

Mark Powell
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Re: K/UV reaction

Post by Mark Powell » Thu Mar 19, 2020 9:28 am

The K/UV+ yellow will almost certainly be useful in helping to separate Lecanora alboflavida from some of its near look-alikes such as e.g. Pertusaria flavida (which is probably K/UV- when someone gets around to checking). However, I would urge you to use these new tests with caution and to use known material as a control until we have more observations. I published my initial observations at an early stage. Being an amateur who isn't chasing grant funding and who doesn't have a professional reputation to defend, I am more free to publish early and this allows others to contribute with novel observations. Negative results and observations that appear to contradict my initial findings are important to record. An intense K/UV+ yellow certainly seems to indicate atranorin. So far I am not aware of other substances that also produce an intense K/UV+ yellow but there may some. I am not very familiar with Lecanora alboflavida myself so I am hesitant to comment too much on that species itself. In more general terms, I think you have probably found another use for the K/UV test but I would want to test look-alikes before relying too heavily on the test for confirming L. alboflavida.

Neil Sanderson
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Re: K/UV reaction

Post by Neil Sanderson » Thu Mar 19, 2020 10:47 am

See viewtopic.php?f=16&t=2519&p=12394&hilit=calicium#p11677. Both Calicium hyperelloides and Calicium lenticulare have K/UV + yellow fluorescence, but if I remember rightly this is visible when still wet.

Neither have atranorin, with Calicium lenticulare with Placodiolic and 4-O-methylhypoprotocetraric and Calicium hyperelloides has some specimens with arthothelin, thiophanic acid, and thuringione andothers with arthothelin and thiophanic acid only.

So yes care needed.

I assume you had very strong UV + orange fluorescence from Lecanora alboflavida, I was noting this as distinguishing it easily from the week UV + orange fluorescence of Pyrrhospora quernea, which it is most likely to grow in the same habitat, at Wormstall Wood last week.

Neil
Neil Sanderson

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