Separating L. pseudargentata from chlarotera s.s.?

Jenny

I am still learning the new species, so finding my way on this. The specimens with pruina on the disks are very distinctive and it is the ones with pruinose disks I was already aware of as unlikely to actually be Lecanora chlarotera s. str., so got one of those sequenced. With the combination of disk and thallus fluorescence it is a lot more distinctive and sequencing should not be necessary identifying well developed specimens. I have been out and around the New Forest looking for more. There is actually a lot about and quite a lot is not very pruinose, but the UV usually finds smaller agglomerations of pruina on some disks and this is key. The thallus UV is not bright but is distinct, other species can show much fainter orange-brown fluorescence but you will know the difference when you see it. Your pictures could be it (I had already looked!) but unless the pruina is visible I can not be sure from pictures. However, all material with dark chestnut-brown disks and a Lecanora chlarotera type crystal distribution has proved to be Lecanora pseudargentata here. As a widespread tropical/warm temperate species I would not be surprised if it is in Ireland. Actual Lecanora chlarotera s. str. all has had pale brown disks so far, as I can tell.

I am finding that Lecanora pseudargentata is locally frequent and the dominant Lecanora chlarotera s. lat. on branches around the edges of pasture woodland glades with wet grasslands and low N deposition. It does also occur somewhere in the canopy with in the woods from its occurrence on occasional fallen branches within the woods. It is absent from more shaded branches within the woods. It is less frequent around dry glades and absent from exposed trees and any with higher N deposition. None around my house on street and field Oaks about 1km from a large population of Lecanora pseudargentata around wet grassland glades. Lecanora chlarotera s. str. seems more frequent away from the edge of the glades on more exposed trees but usually still low N conditions and Lecanora hybocarpa s. lat. is more frequent on more nutrient enriched twigs.

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Looking into prime Lecanora pseudargentata habitat, Busketts Wood

Neil

Some more UV pictures:

Lecanora argentata from branch on Oak, Denny Wood:

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Faint orange-brown fluorescence on the margins, nothing on the disks.

Lecanora pseudargentata from the same branch on Oak, Denny Wood:

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Stronger orange-brown fluorescence on the margins, the disks are not strongly pruinose, but speckled UV+ grey-blue fluorescence on the disks is noticeable.

Neil

Hi Neil

I photographed this years ago (3/4/2011 to be precise) on an Aspen in Browndown Fen, Gosport (images are not very sharp). Is it a candidate for L. pseudargentata? If so, I could go back to get better photos and a small specimen to send you. I remember at the time it matched something labelled as L. hybocarpa on the internet, but I think you said it was a ‘maybe’ based on what your idea of that was at the time.

John Norton

Playing around with more Lecanora chlarotera s. lat. picked up today, I found a Lecanora chlarotera s. str. thallus that also had UV+ brown-orange fluorescence on its thallus. Looking up LGBI3, this species is described as having ±gangaleoidin. So I guess I had collected a gangaleoidin containing chemo-type. The disks were still pale brown and had no fluorescence:

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Lecanora chlarotera s. str. with UV+ brown-orange fluorescence on its thallus, which presumably contains gangaleoidin.

Neil

Jenny

Yes that seems to be the minimum for Lecanora argentata, which is always supposed to have gangaleoidin. The same twig that had the gangaleoidin containing Lecanora chlarotera s. str. also had a Lecanora argentata with a much stronger UV+ reaction. All lacked any hint a UV+ blue-grey fluorescence on the disk.

Neil