A crustose lichen to ID (Lecanora?)

[lettuce]

Hello there,
I've started to visit this forum more often to read your lichen IDs. I'm quite new with lichens and perhaps you can help me out with this one.

This lichen was found on a concrete railroad bridge. No obvious chemical reactions (except I/KI which colors the hymenium blue), has 8 spores which are simple and colorless, paraphyses are rather branched (tips are a bit swollen and seem to be colorless after K, can't tell if they were brown beforehand), epithecium has this brown layer that dissolves in K.

I thought Lecanora dispersa, but literature says the epithecium granules dont dissolve in K. Then perhaps L.semipallida, but the apothecium margin doesn't give any chem.reactions (I was working with little material and I dont have Pd). Any ideas?




One more question! I've read about Lecanora species having crystals, but I'm not sure what they look like or what should I be searching for. I've seen something, but those could be sand particles? Can these crystals be readily observed or do I need polarizing light?

Thank you very much, hope you have some ideas about all this!

[diggleken]

Hi lettuce, welcome to WAB!
Brilliant to have another lichen bod on here, there arent many of us!
You sound to be more progressed than I am with them anyway, and I'm no expert (we do have some, but may be sunning themselves in the caribbean...........or Cork or snowed up in Scotland etc etc)
So, for what its worth, yours seems close to Lecanora dispersa I agree, but Dobson mentions similar species in the dispersa group, one of which is L semipallida, which he says there is also a form, L xanthostoma, which has yellow margins to the apothecia, so you could have those two together?
Hope this helps a little.
Cheers
Ken

[lettuce]

thanks Ken for your reply! I'll dig a bit deeper into the literature and try to figure it out, perhaps take a trip to the bridge and look for another sample.

Well I'm no lichen expert either, but I am passionate about lichens. I use Dobson 2011, Smith et al. 2009 and Wirth 1995.
Anyway, I'm from Croatia and only a couple of people are into lichens professionally, quite a depreciated science branch (not to mention mosses).
We have just over 1000 lichen species here, most were noted 50 years ago so this needs revision.

[Chris Yeates]

I've read that Lecanora dispersa sensu stricto has "epihymenial granules" could that be what we are seeing here?

cheers

Chris


uh-uh! just re-read the original post - ignore the above weak contribution

[AlanS]

Hi Lettuce,

What you have looks like normal Lecanora dispersa to me, but these small Lecanora species are difficult and here in Britain we are perhaps too ready to dismiss a lichen as L. dispersa without considering other possibilities. I am assuming your site is not coastal, as this would bring in more species of the L. dispersa group to consider.

There is some black around the apothecia, which raises the possibility of L. semipallida, but I think this black material is the prothallus of the Candelariella (the yellow apothecia adjacent to and mixed with the Lecanora - likely to be C. aurella but I don't trust IDs of this species made without microscopic confirmation, and I don't know what else you have in Croatia). Accordingly, I am assuming the thallus is within the substrate surface, which supports this being L. dispersa. In any case, you appear to have ruled out L. semipallida on chemical grounds.

Your photomicrograph is, unfortunately, too small to see the critical detail, but possibly you are confusing two different materials here. There may often be some brown 'gunk', around and above the tips of the paraphyses, that dissolves readily in KOH or ammonia and not in a water mount, but L. dispersa also, to cite Smith et al. and as you say, has an epithecium "densely interspersed with granules not dissolving in K". This means that the granules, which are very small, are down amongst the paraphyses and in fact are easily missed without careful microscopy. I wonder if you have looked in the right place for these granules? (How many people ever bother to look?) So I suggest you re-examine the material if you can - I do think this is L. dispersa so I think the granules are there.

Crystals
I should explain at this point that my own microscope is equipped with Nomarski DI Contrast, which I routinely use for fungal/lichenological work. It is very good for clarifying transparent objects such as crystals, so what is clear to me is not going to be so clear to someone relying on standard bright field microscopy. So if I find it easy not to notice granules in the epithecium, then they are indeed easily missed. This also affects my comments on the larger crystals, which are usually (to me) easy to see in those species that have them.

I suggest that if you have Lecanora chlarotera as a common species in Croatia (with us it is common on young, smooth-barked trees, forming conspicuous, rounded, whitish thalli and has pale (to dark) brown, non-pruinose apothecia), then you should collect a little and make a series of sections. You should easily enough see the large crystals in the apothecial margins (as on page 222 in Dobson ed. 6) and so get to know this character. Also, if the material is indeed L. chlarotera, you will see the thin layer of much finer crystals covering the hymenium, but again you need careful microscopy at high magnification and condenser lens correcty set in order to see detail.

Books & stuff
So welcome to the lichen subforum. With your detailed, systematic approach, I shall be interested to see any further contributions you make. Of course most of us are here right on the oceanic fringe of Europe, so you may well post material beyond our own experience.

You have probably the best three books you could be using (though note that many photographs, including L. dispersa, are very poorly printed in the 2011 Dobson). Of no use in the present context but an excellent book for lichens on soil and plant debris is P.L.Nimis & S. Martellos (2004) 'Keys to the lichens of Italy. I. Terricolous species', Edizioni Goliardiche, ISBN 88-88171-73-8 (text in English). No pictures, but detailed descriptions, and geographically highly relevent I should think.

Also, at least for the western Mediterranean, Valcarcel et al. (2003) 'Guia dos liques de Galicia' Baia Edicions, ISBN 84-96128-49-0, in Spanish, is worth having. In general it is good for crustose species, including Lecanora, but there are a few cases, primarily macrolichens, where the photographs do not match my own experience of the species. Whether that is a comment on the book or on me ... ?

Alan

[AlanS]

Originally Posted by lettuce

but I am passionate about lichens

P.S.:

Lichens are addictive, but looks like this warning comes too late ...

Alan

[lettuce]

Hi Alan, thanks very much for the detailed (and interesting to read) reply!

I believe it is L.dispersa, but I'll certainly take another look the first moment it's possible (it's a bit snowy right now).

I do not have Nomarski DIC, but I've read that transparent objects such as crystals can be clarified using the lenses of polarized sunglasses - have yet to try that one out.

By the way, you are right on Candelariella aurella, I had just IDed it before the Lecanora specimen.

Thanks for the insight regarding crystals and literature; I'll check whether and where I can get those books.