Growing on the wood of an old Juniperus shrub at a cliff over the sea.
I was wrong again and maybe with the same error than before. In fact, I was very confident that this one should be Buellia (and particularly B. erubescens), taking into account the appearance and the chemistry. But, as soon as I saw an apothecial section I started to doubt and, seeing the spores, I was sure that this is not a Buellia. On the other hand, these micro features clearly point to Lecidella.
Now, the question is: what species in this genus can have such chemistry? I found no alternative.
I attach plenty of information from the microscopy; however, I cannot give precise values for the dimension of the spores and only give the average dimensions:
Me = 12.6 × 6.9 µm ; Qe = 1.8,
where some of the spores were measured still inside the asci.
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then I will be a rich collector; this is far from being the case though …
Just checking! :) Looks like you have a great view of the micro features!
Based on my experience I know that the chemistry of Lecidella can be difficult to understand, mainly the C and KC reaction, for which in the British Flora it mentioned the following: “Chemistry: atranorin, chloratranorin, zeorin, diploicin and frequently a range of xanthones” …“chemistry which includes a preponderance of xanthones, making the thallus react C+ orange”. This is particularly applied to L. elaeochroma. However, as a matter of fact, the sucessive specimens that I found don’t fill this requirement or present some dubious reactions. But in this case, the question is more related to the K reaction, which clearly started with yellowish and progressively changed to red. No species is cited in the British Flora with this type of reaction on thallus.
As Jason said, in the beginning everything seems out of our possibilities. But with time and persistence you will do every time better and I´m sure you will find your appropriate way of doing things. i.e. with some inspiration and a lot of sweating you will arrive to the point of observing what it is in the slide to observe. Everyone of us is learning …
Now I just need time at the microscope desk…lots to come, in time. Thanks to you both!
I found this to be extremely difficult to learn to do. It took me years. (Partly because I found it so daunting, so I was too scared to try, and wouldn’t trust myself at all.)
Thin sections definitely help. Squashing definitely helps. Just be careful not to squash too hard — you can easily burst all the asci and make a big soup of it.
It can also help to squash it just slightly after you first draw K through. K dissolves tissues and loosens everything up. Then rinse the K with water and draw Lugols solution through, just like usual. If you squash too much with K, I find that it will often refuse to draw water and Lugols later. If you have trouble getting your Lugols to draw, it helps to have the section near the edge of the slip. And it helps to add some drops of water. You can always add more Lugols later.
Also, another thing that really helps me is not just to squash the coverslip (e.g., with a pencil eraser), but to gently swirl the coverslip around while gently pressing down on it.
Lastly, some genera are prone to overstaining, Lecidella being a prime example. If it’s too dark even the perfect ascus will hide its structure. After you’ve got a good mount with asci well-separated out and (over)stained, just add a drop of water and wait for the stained asci to start to fade. When it looks right, “quench” it by swiping a tissue over the coverslip to sop up all the excess water, while holding a corner of the coverslip firmly in place. (This is also very helpful for clearing “fingerprints” off of the surface of the coverslip. If your section looks blurry, that is probably the problem.)
But most important, practice! patience! and don’t get discouraged.
And remember, half of it is knowing which asci are at the appropriate stage of maturity. Often only a few will actually stain correctly and show the correct structure in the tip.
(In Zaca’s last photo, look at the ascus in center-left. That’s exactly what you’re looking for in Lecidella — a lighter “axial mass” that extends up from the center of the ascus, but apparently doesn’t penetrate completely because of a thin darkly stained layer right at the tip. This is very similar to bacidia-type, but the axial mass is broader and more parallel-sided. Bacidia-type is even fainter, narrower and spikier. It is also similar to lecanora-type, except that in lecanora-type the axial mass is even lighter, and it extends all the way to the tip.)
I learned from them.
I use the technique you mentioned “press the slide cover to squish everything apart a bit”. However, this only works is the initial section is thin enough, otherwise you will not be able to see the elements clearly. Sometimes this requires pressing the slide several times, inserting some water from the sides of the slide in order to make the slip smooth.
I´m glad that you enjoyed the photos.
Great microscopy photos! Can I ask, how do you get the asci to show so clearly? Are they in place within the apothecial section, or do you press the slide cover to squish everything apart a bit? I think my sections have been a little too thick, making it difficult to isolate them on one plane for photos that are in focus throughout.
Chemistry is so rich and variable in this genus, even within some polymorphic species. It wouldn’t surprise me at all if you find one with a hint of some anthraquinone or something even more strange.
Nice image of ascus stain, by the way; absolutely perfect example of lecidella-type ascus!
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