Ramalina with medulla K+ pink-red

Glos lichens
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Re: Ramalina with medulla K+ pink-red

Post by Glos lichens »

I'll have to get the Pd out.
Actually, I'd rather they were bog-standard fastigiata. One less thing to worry that I might have been recording wrongly all these years.
Juliet
Glos lichens
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Re: Ramalina with medulla K+ pink-red

Post by Glos lichens »

All my specimens are Pd -ve
Juliet
Mark Powell
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Re: Ramalina with medulla K+ pink-red

Post by Mark Powell »

I have managed to produce the K+ pink-red reaction in specimens that I would normally call Ramalina fastigiata. There is certainly something odd/interesting going on. I visited a hedgerow in North Bedfordshire, a harshly trimmed and largely dead blackthorn hedge, on which there are numerous thalli of Ramalina 'fastigiata' displaying a wide range of morphology despite growing in exactly the same conditions. Being excited by the posts above, I tried to split them into different forms in the field, some thalli quickly becoming abundantly fertile, giving the full 'fanfare of trumpets' effect. At the other extreme were thalli which seemed more reluctant to produce apothecia and remained more like scraggy tufts, their apothecia often arising on sides of branches rather than mainly terminal. However, there seemed to be a full spectrum of intermediates.

I was 'hoping' that the scraggy individuals would give a K+ reddish reaction and the 'fanfare of trumpets' type would prove K-. This hope was soon dashed as six out of seven individuals so far tested produced some sort of reaction and the 'fanfare' type seemed (from this small sample) to give the more intense reactions. I'm afraid that I don't have any photos of my own just now but I will re-post one from above which illustrates exactly the sort of effect that I have observed in specimens which show a distinct reaction.
20231121_190644_190643719T.jpg
20231121_190644_190643719T.jpg (43.04 KiB) Viewed 373 times
Something I notice is that the reaction is most intense if K is applied to the medulla beneath a young apothecium and it was here that I noticed that the reddish reaction gives a rather intense K/UV+ magenta fluorescence once the reagent has dried and when the reaction is quite strong. This suggests to me that our K+ reddish reactions are detecting a distinct substance, rather than being some other type of effect. I have failed to obtain any hint of a Pd reaction, even with very strong fresh alcoholic Pd solution, which probably rules out substances such as norstictic, stictic, protocetraric or salazinic acids.

I examined spores in one of the 'fanfare' type specimens and find that they vary from straight to curved, and from narrowly to broadly ellipsoid, even in one apothecium. As others have noted above, the ascospore size is somewhat intermediate between published sizes of pusilla and fastigiata but probably straying into the larger range of fastigiata. My range compiled from a dozen random loose spores: (3.5-)5-5.5 x (10-)12-13.5(-15) microns.

My tentative hunch is that my North Bedfordshire specimens are all Ramalina fastigiata and that most or all contain some unknown (to me) substance which is K+ reddish, K/UV+ magenta (dry). If this proves to be the case, it rather disappoints me that there isn't something else hiding in plain sight but who knows, it is early days in this interesting investigation. Whatever is the case, it is important to note that widely distributed specimens that we would normally record as R. fastigiata seem to display a K+ reddish reaction. The literature often expects us to observe far more subtle effects than our reddish reaction in 'fastigiata' so it will be important eventually to work out whether or not we are observing a reaction that occurs in R. fastigiata but which hasn't been noted previously.
Mark Powell
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Re: Ramalina with medulla K+ pink-red

Post by Mark Powell »

If we have detected a K+ reddish reaction in Ramalina fastigiata, it won't be the first example of a noticeable reaction that is ignored in the published accounts. Many or even most British specimens of Candelariella vitellina give a noticeable K+ reddish reaction, especially in the proper margins of the apothecia but this is not mentioned in the literature. This reaction sometimes causes confusion, especially for beginners who think the presence of any such reaction must indicate that the specimen belongs to Caloplaca s. lat. On the other hand, the soralia of Porpidia soredizodes are stated to be "K+ yellow" without any explanation that this reaction is often effectively undetectable in the field, being very weak. The unmentioned K+ reddish of C. vitellina is usually considerably more conspicuous than the stated K+ yellow of P. soredizodes.

Here is Candelariella vitellina showing the K+ reddish reaction in the centre of the image.
EMisd2PXkAEcH9u.jpeg
EMisd2PXkAEcH9u.jpeg (101.59 KiB) Viewed 361 times
GERAULT
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Re: Ramalina with medulla K+ pink-red

Post by GERAULT »

This brown-yellow reaction with KOH would be due to a yellow pigment: calycin, it is very variable and not all tests present it.

http://www.lichensmaritimes.org/index.p ... 40&lang=en
Mark Powell
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Re: Ramalina with medulla K+ pink-red

Post by Mark Powell »

I'm not sure whether the reaction that I observe in the Candelariella vitellina is the same as your brown-yellow reaction which you suggest is due to calycin. The reaction that I observe is most apparent in (perhaps largely restricted to) the proper margin of the apothecia. It is a distinct and attractive reddish colour. In section a distinct reddish colour becomes apparent when K is added. The following two photographs show the effect.
Cand vitR4H2O.jpg
Cand vitR4H2O.jpg (39.4 KiB) Viewed 331 times
Cand vitR3K.jpg
Cand vitR3K.jpg (37.54 KiB) Viewed 331 times
I can't be certain whether the reddish substance actually appears on adding K, or whether it is largely masked by substances which are removed by K. Here is the effect seen in section, the same portion of apothecial margin, first mounted in water, and then after adding K.
Cand vitellH2O.jpg
Cand vitellH2O.jpg (35.67 KiB) Viewed 331 times
Cand vitRK.jpg
Cand vitRK.jpg (29.23 KiB) Viewed 331 times
Whatever the cause, this reaction is so readily observed that beginners who are inexperienced in conducting spot tests nevertheless often observe it, and get confused by it, and it is curious that it is rarely if ever mentioned in the literature.
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