Peltigera sp

[black]

Opininons welcome on the identity of this Peltigera sp. photographed at the weekend at Wigan Flashes, Gtr Manchester. Thanks

[Fungus Ken]

I'm not a lichen expert but Peltigera hymenina is a possibility. It is very common and has the type and shape of red-brown "fruiting" structures, or apothecia, shown in your photos - "raised, curled, digitate lobe tips" it says in Frank Dobson's "Lichens".

Ken

[black]

Thanks Ken, you're not Fungi Ken from Lincs are you?

[Fungus Ken]

No. I'm based in Manchester.

Ken

[AlanS]

Hi Black,

This one is tricky. As always, the underside of a Peltigera is vitally important for identification and even though we can see a little of the underside here, it is of the marginal region of a new lobe and could be misleading.

As Ken has suggested, Peltigera hymenina (= P. lactucifolia) is a strong possibility. It is much the most common of the dog lichens with a smooth upper surface.
However ...
The underside is evidently white, whereas the underside of P. hymenina, even to the edges of the lobes, is usually distinctly yellowish or tinged pale brown. Such rhizines as are visible are branched, which they are normally not in P. hymenina.

The best alternative seems to be P. polydactylon ('polydactyla' in British books but this is incorrect). P. polydactylon usually has a more crispy margin and distinctly dark veins on the underside but, on the other hand, the rhizines look to be just right - initially grey and sparsely branched (they later turn brown).

Either way we do not know the true vein colour as they are at least yellowish brown in P. hymenina.

If we had a view of the underside of the mature thallus, the colour of the veins and a better view of the rhizines, the matter could be settled. As it is, I don't feel this photograph is certainly identifiable. I am inclined towards P. polydactylon, as your photograph does look like material I have at a local site - really good dark veins underneath but with these misleadingly white at the margin - but it is certainly the less common species. I could very easily be wrong.

Oh, and just to make matters more complex, up until the publication of the The Lichen Flora of Great Britain and Ireland* in 1992, 'P. polydactyla' was the name in use for what we now know as P. hymenina!

Alan

*British Lichen Society. Out of print but new edition supposedly imminent.