Athallia (Caloplaca) pyracea?

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Glos lichens
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Athallia (Caloplaca) pyracea?

Post by Glos lichens » Sun Feb 10, 2019 4:19 pm

I’d be very grateful for confirmation (or otherwise) of my identification of this Caloplaca found growing on a twig of a poplar next to the River Severn in Gloucestershire.

Using the Arup key to species similar to Caloplaca holocarpa in northern Europe in The Lichenologist 41 (2) 2009 I get to Caloplaca pyracea (now Athallia pyracea). This would be a county first, though I note that it is now thought that this species is widespread in occurrence, most commonly encountered on, but not restricted to, aspen.

Juliet
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Micron scale, spores 11x7 microns, septum 4-5 microns, 8 per ascus
Micron scale, spores 11x7 microns, septum 4-5 microns, 8 per ascus
Thalline and proper margin. Low small greyish areoles.
Thalline and proper margin. Low small greyish areoles.
Section of two youngish apothecia.
Section of two youngish apothecia.
Caloplaca pyracea on poplar twig. mm scale. The sectioned fruits are top left. I think the green stuff is free-living algae.
Caloplaca pyracea on poplar twig. mm scale. The sectioned fruits are top left. I think the green stuff is free-living algae.

Neil Sanderson
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Re: Athallia (Caloplaca) pyracea?

Post by Neil Sanderson » Sun Feb 10, 2019 10:40 pm

Juliet

Looks fine to me for Caloplaca pyracea, although I have not seen it much. Mark knows it much better.

I have attached a photo of a specimen from a White Poplar, collected in 2011, from North Hampshire

Neil
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Caloplaca pyracea
Caloplaca pyracea
Neil Sanderson

Mark Powell
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Re: Athallia (Caloplaca) pyracea?

Post by Mark Powell » Mon Feb 11, 2019 8:58 am

I agree that it looks fine for C. pyracea. It has the definite grey thalline margin which then often becomes rather excluded as the apothecium matures. My decision is based much more on gross morphology than any microscopic characters.

It is turning up quite regularly in my part of the world, most commonly on aspen (twigs and small branches) but also sometimes on other trees. In Derbyshire, Brian, Steve and I were finding it on low-hanging Fraxinus branches. Perhaps one of the more surprising occurrences is on the trunk of a young Platanus tree in Exhibition Road near the Science Museum. I have also seen it on paint (which often develops a 'twig' community). LGBI2 (2009) mentioned it as a note within the description of C. holocarpa and at that time it was considered a rarity of Scottish aspen. I suspect two things have happened - that it has become more common but also that we now distinguish it from other Caloplaca spp.

In my opinion you could record this as the county first.
Mark
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Caloplaca pyracea 1.jpg
Caloplaca pyracea 2.jpg
Caloplaca-pyraExRd.jpg

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Chris Johnson
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Re: Athallia (Caloplaca) pyracea?

Post by Chris Johnson » Mon Feb 11, 2019 9:28 am

Thanks for posting Juliet, and for the Arup key reference which I have managed to download.

Chris

Glos lichens
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Re: Athallia (Caloplaca) pyracea?

Post by Glos lichens » Mon Feb 11, 2019 10:37 am

Thanks for your confirmation, and for the comments and photos, Gentlemen.

Exhibition Road - amazing!

Athallia pyracea might be spreading, but I really don't think it is common in Gloucestershire yet. I collect a heck of a lot of twigs, and this just jumped out as being different. It is so much bigger and more bright and orange than Caloplaca cerinella which is on nearly every twig of ash, willow, elder, walnut, poplar etc that I look at.

(I usually try to examine at least one "cerinella" per site microscopically, just to check it isn't cerinelloides. I've never had one yet with only 8 spores. If I remember, I note on the BLS database input spreadsheet that the spores per ascus were counted.)

I don't know wht species of poplar it was on, though I doubt it was aspen. I grabbed a twig whilst out on a Gloucestershire Naturalists' Society meeting looking at curlews, in great danger of scaring the flock and getting a black mark and stern looks from the leader.

Juliet

Mark Powell
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Re: Athallia (Caloplaca) pyracea?

Post by Mark Powell » Mon Feb 11, 2019 11:34 am

Hi Juliet,
I agree with all your comments about these corticolous Caloplaca species.

C. pyracea does stand out as something different.

I check quite a few C. 'cerinella' specimens and find they ARE almost invariably C. cerinella.

I very occasionally come across 8-spored Caloplaca on smooth bark and my interpretation is that these belong to C. holocarpa s. str. I have recorded this on smooth poplar branches. I suspect that some or many records of C. cerinelloides are actually of corticolous C. holocarpa.
Mark

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