Brown crustose lichen

[Bruce Williams]

Stony Stratford, Bucks. On (probably) limestone.

Help with identification appreciated:



Bruce

[JennyS]

A beautiful close-up but do you have a photo showing the whole thallus as well?

[Bruce Williams]

Thanks for your interest Jenny - does this help?



Bruce

[AlanS]

Hi Bruce,

I am reasonably sure this is Verrucaria macrostoma - a locally common species on limestone and occasional to frequent on concrete.

It looks like dried mud and can be confused with Acarospora species (though the latter are more common on nutrient-poor rocks). Your photographs apear to show perithecia - flask-shaped fruiting bodies that in this species are more or less immersed in the thallus. Acarospora species have disk-like apothecia as fruiting bodies, but these too are sunk into the thallus surface.

Verrucaria is a large and nasty genus, but this one is moderately distinctive!

As you are doing a lot of excellent lichen photography, then if you do not already have it, I recommend purchase of F.S. Dobson's 'Lichens: an illustrated guide to the British and Irish species' (5th edition), published by Richmond Publishing, ISBN 0 85546096 2 (paperback, apparently no longer available in hardback). It contains less than half the British species, but nearly all of those not included are very rare or montane, very inconspicuous or in groups needing a lot of microscope/chemical work. I always feel a sense of achievement when I succeed in photographing a species not in Dobson!

Alan

[Bruce Williams]

Alan - Thanks for the ID and information. I'll check out availability of the Dobson's guide tonight.

Bruce