Page 1 of 1

Athallia (Caloplaca) pyracea?

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

Re: Athallia (Caloplaca) pyracea?

Posted: Sun Feb 10, 2019 10:40 pm
by Neil Sanderson
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

Re: Athallia (Caloplaca) pyracea?

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

Re: Athallia (Caloplaca) pyracea?

Posted: Mon Feb 11, 2019 9:28 am
by Chris Johnson
Thanks for posting Juliet, and for the Arup key reference which I have managed to download.

Chris

Re: Athallia (Caloplaca) pyracea?

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

Re: Athallia (Caloplaca) pyracea?

Posted: Mon Feb 11, 2019 11:34 am
by Mark Powell
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