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Lichen ID help please - Lecidea lithophila ?

Posted: Mon Feb 03, 2020 5:18 pm
by Mark Walters
Hi

I am a beginner with lichen identification (can identify the basics but no chemicals or compound microscope yet). I am leaning towards Lecidea lithophila for this one recorded at Craig Rhiwarth hillfort, Powys, Wales on siliceous mudstones (thin quartz veins) altered by igneous intrusion. The outcrop is on top of a hill with lead mines below and a good community of lichens. The thallus is cracked-areolate with rust-red patches and a light grey margin. The apothecia look like lithophila on the outer rusty thallus, but look more flattened and splayed toward the centre (age related ?). I looked at some of the Rhizocarpon species with a rusty thallus (R. anaperum and R. oederi) but they do not seem to key out right. Also looked at Tremolecia atrata and that doesn't match. As i'm looking to submit the records I was keen to get some expert opinions. Any help much appreciated.
lithophila2.jpg
lithophila3.jpg
lithopholia4.jpg

Re: Lichen ID help please - Lecidea lithophila ?

Posted: Mon Feb 03, 2020 6:41 pm
by AlanFUSA
Hi Mark:
Nice pics!
Definitely a Lecidea sp. and L. lithophila is a very good shout. However, the apothecia in that species are usually brown - especially when wet - because of the brown epihymenium. I would tend towards L. lapicida - which has a blue-green epihymenium - but it is really impossible to be certain without cutting a section.
Alan

Re: Lichen ID help please - Lecidea lithophila ?

Posted: Mon Feb 03, 2020 8:42 pm
by Mark Walters
Hi Alan

Many thanks for pointing out the alternative ID. Having compared a few lithophila and lapicida photos online now the lapicida seems a better fit, particularly the flattened form of the dark apothecia.

It is clear that visual identification from photographic records alone of lichens isn’t going to result in many firm ID’s that can be passed on as definite records except for the few really distinctive species, and even they can throw up problems. Mark Powell on Twitter has also been really helpful with ID’s before I found this forum, but I don’t want to inundate people with ID requests. A rapid move to chemical tests and microscopic examination of cut and squashed samples seems inevitable. It’s a steep learning curve but a fun one !

Re: Lichen ID help please - Lecidea lithophila ?

Posted: Tue Feb 04, 2020 7:53 am
by Chris Johnson
Hello Mark, welcome to the forum.

Don't be phased by inundating us, we actively encourage all levels of ability and are willing to help. Clearly, we don't want too many 'what is this, questions' without any effort put in but you have made a thorough attempt at identification.

Regards, Chris

Re: Lichen ID help please - Lecidea lithophila ?

Posted: Tue Feb 04, 2020 10:58 am
by Mark Walters
Hi Chris

Thanks for the welcome and encouragement. Will certainly post up if I hit any problems with ID's or other interesting snippets.

All the best, Mark