Unidentified lichens from my Sunday walk

[diatom dave]

Found these little beauties while out on a walk over the weekend. Finding it very difficult to identify them though because I'm very new to lichen id. Can somebody please help? The crustose ones were found on a sandstone wall at around a thousand feet on moorland in the Pennines

[JennyS]

Hi Dave,

Photo on left:
LH is Ramalina farinacea (fruticose) and RH is Hypogymnia tubulosa (foliose)

Photo on right: It's a Cladonia but I'm suffering from a serious crisis of confidence in my ID ability with these at the moment - you need AlanS for more help!

[diatom dave]

Thanks Jenny... now that you have told me what they are my lichen book makes sense!

[AlanS]

Jenny is very sensible to duck the Cladonia - it is a difficult one.

Some people consider that Cladonia coniocraea (very common on trunks and stumps in dampish places), and C. ochrochlora (somewhat less common in similar habitats) are both forms of one, variable species.

Personally I don't, or didn't, but your photograph is almost perfectly intermediate between them! There is resemblence to C. ochrochlora, with nearly all the podetia (sticky-up bits) terminating in small cups that are sometimes wider than the podetium, and each cup with crown-like points from the ring of minute, brown perithecia. However, C. ochrochlora should have corticate patches (patches of "skin"), whereas your photographs show the podetia to be very uniformly covered in soredia, and C. ochrochlora has more distinctly yellow-green tints whereas your photograph suggests a uniform grey-green.

On balance I would say this is well-developed C. coniocraea. There are other species, notably C. subulata, that normally lack cups but which can sometimes have populations with them very well-developed, and this tendency for Cladonia to produce populations outside our usual experience is one aspect that makes the genus so difficult. We think we know a species and we don't. So I think this is most likely C. coniocraea, but not in its usual state. I am assuming it is brown-fruited.

As for your crustose species - well crusts have to be worked at. Chemical testing is near-essential, and checking of microscopic characters is important. I am slowly learning them myself, but there are quite a lot of crustose species for which I have photographs but not yet on my website, because I will not name them for certain until I have done the work. So it follows that if I won't put definite names to my own photographs yet, I am reluctant to name them for others.

So the following are suggested names - a basis for you to go back to the book and check key features (including, in my view, microscopic ones).

Bottom centre and bottom left (whitish grey with blue, soredate patches) - Porpidia tuberculosa - often very common on acidic sandstone rocks and stonework (Dobson picture is correct but shows unusually dark soredia imo).
Pretty much centre, whitish grey patches with concentric rings of small, black apothecia - Rhizocarpon petraeum - also locally common on acid sandstone rocks.
Somewhat greyer, circular colony, to the right of the putative R. petraeum, also with concentric apothecia but these looking a little larger - possibly Rhizocarpon reductum - also common and variable in the same habitats.
The greeny brown one I could guess at, and I think it is something quite common, but it is not a species I understand yet, so no name. The green may be 'escaped' algae on the thallus surface, so don't always expect crusts to look like pictures in books!

Incidentally, this set of species is not unlike an old baryta mine near me. The rocks would seem to be very nutrient-poor and yet I am wondering if there might be some unusual metal content. The worked rock surfaces are blue with sheets of Porpidia tuberculosa and virtually nothing else, while rocky spoil from the mine is completely dominated by Rhizocarpon petraeum.

Alan

[diatom dave]

Thanks Alan. Even though, especially as a beginner in this field, it is great to get definitive answers to questions, it's probably more stimulating and in the longer term more effective to sometimes receive a tentative reply. It encourages the novice (well it certainly does in my case) to further thought, investigation and discovery rather than just relying on other peoples experience and knowledge. That's what makes science so exciting.