One for ID Please

[Teal]

Help with ID of this lichen please. Took these photos yesterday 18/1/11 on West Wales Coastal Path. The closest I could get (in my ignorance) was Xanthoria parienta which I favour, or possibly one of the Caloplaca species possibly C.marina. Thanks.

[AlanS]

Hi Teal,

Your first choice is correct - this is Xanthoria parietina. It's looking a bit water-soaked, so not quite typical.

In case you want to know, the white one with the black disks that is co-dominant with the Xanthoria is mostly Tephromela atra. They very often grow together on coastal rocks, though quite often it's a different Xanthoria when examined closely.

Alan

[Teal]

Thanks for that Alan. I'm a novice with lichens so, what are the main differences between the Xanthoria and Tephromela if some species can be confused?

Mike

[AlanS]

Originally Posted by Teal

Thanks for that Alan. I'm a novice with lichens so, what are the main differences between the Xanthoria and Tephromela if some species can be confused?

Mike

Ooops, my post was somewhat ambiguous.

To be clearer, Xanthoria parietina (yellow) and Tephromela atra (creamy white, black discs) often grow together, dominating coastal rocks above the main splash zone.

However, quite often, instead of Xanthoria parietina, the Xanthoria is X.aureola (as currently interpreted, though should really still be called X. ectaneoides). It is also yellow and resembles X. parietina closely, the differences being rather subtle.

So either Xanthoria (or both species together) can form the zone with Tephromela. There is no confusion between Xanthoria and Tephromela.

(There is another lichen, Lecanora gangaleoides, that closely resembles Tephromela atra, but let's not go there ...)

Alan

[Teal]

Thanks Alan,
Now clearer than before. What are the subtle differeneces between parietina and aureola?

[sarahwest]

Hi Teal
I'm just starting out with identifying lichens, but I've found Dobson's "Lichens: an illustrated guide to the British and Irish species" book very informative - lots of the groups have keys to help with identification, and the descriptions are very good. Some of the pictures are a bit unclear but there is a great website at Irish Lichens - Index (not just Irish species).
Hope that helps a bit.

Sarah

[Teal]

Hi Sarah,
Thanks for that. Think Dobsons book is out of my league prciewise!! The Irish site is indeed useful and complements those I already use.

I am rapidly getting the impression that the Lichen taxonomists can not agree on any nomenclature as it seems they all use different names which is even more confusing!!

Mike

[sarahwest]

Very true! The lichenologists would probably blame the "pesky molecular ecologists" for the emerging DNA evidence.
I got Dobson off ebay a while back for about 20quid, so keep an eye out!
The best way to learn though is to follow a lichenologist around in the field, the British Lichen Society The British Lichen Society can put you in touch with someone locally, and they are also running introductory FSC courses (see the link on the bottom left of their website) which are only £20 for the day, as they are heavily subsidised.

[AlanS]

Originally Posted by Teal

Thanks Alan,
Now clearer than before. What are the subtle differeneces between parietina and aureola?

In the field, there is a slight difference in colour, a more golden orange towards the lobe bases, that marks out X. ectaneoides ('aureola' in the sense of the new BLS lichen handbook) from X. parietina when they are growing together. X. ectaneoides has distinctly strap-shaped lobes and is often less ready to produce apothecia.

See more discussion here:

Xanthoria ectaneoides (images of British lichens)

Many have questioned whether they are really separate species, and I don't think it is possible to identify young colonies on morphology, but I believe that recent DNA work has shown they are separate.

Alan

[AlanS]

Originally Posted by Teal

Hi Sarah,
Thanks for that. Think Dobsons book is out of my league prciewise!! The Irish site is indeed useful and complements those I already use.

I am rapidly getting the impression that the Lichen taxonomists can not agree on any nomenclature as it seems they all use different names which is even more confusing!!

Mike

Lichen names have gone through a major review recently, ready for the new BLS handbook (C.W. Smith et al., The lichens of Great Britain and Ireland - massive tome, technical descriptions, a few line drawings but no photographs, already out of print but reprint planned). Important changes were previewed in the 2005 edition of 'Dobson'.

However, despite my being awkward about 'Xanthoria aureola' (which I may do something about formally), I think we are now in a period of stability. The problem arises when people are still using old (but undoubtedly treasured) books.

One major change in the past few years, has been the splitting of the large, old, cumbersome Parmelia genus, but the result has been a much more sensible and useful classification, with related species grouped together, and only a few, clearly allied species remaining in Parmelia.

I would say, from such experience I have so far of BLS meetings, that lichenologists are pretty much using the same names now.

I posted an interim summary of lichen identification resources (books, websites) in a lichen thread in the main fungi forum, here (if the link works):
Help to ID please.

Sometime I'll write a more complete version and post it here.

I do think that 'Dobson' is indispensible!

Alan