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Light grey thallus with dark soredia

Observed: 13th November 2012 By: pf339
S159 Neighbourhood Nature - course complete
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Light grey thallus with dark soredia a
Light grey thallus with dark soredia b
Light grey thallus with dark soredia c

Thallus of light grey knobbly areoles with dark fimbriate prothallus growing on siliceous gravestones. Balls of ‘steelwool-like’ soredia sitting near middle of thallus. Possibly Lecanora pannonica.


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Some fungi are very poisonous so a mistaken ID could have serious consequences.

Species interactions

No interactions present.


synan's picture


I haven't encountered this, but it does look a lot like one photo on the British Lichens site. The description in Smith et al. of "prothallus absent" and "plane or excavate soralia" has me puzzled; the soralia in your photos really do look like balls of steel wool! However, I think you must be right.

The black blobs in the background of the second photo have drawn my attention. Could they be the apothecia of L. pannonica (not yet seen in Britain), a lichenicolous fungus or something else?


pf339's picture

A third image now added.

Many thanks Nigel for looking at these images (and the images for other lichens). I had no idea what it might be before eventually suggesting, but not confidently, L. pannonica . It doesn't seem promising especially the details you passed on:"prothallus absent" and "plane or excavate soralia".
The photo in the link you sent also seems to have a dark edge to its thallus. (Perhaps structurally that dark edge isn't a prothallus but technically some other feature.) (Still hopeful!)
I hadn't registered the black blobs so your comment made me look again at all the images. I have added a third picture showing lots of black blobs. (I hadn't noticed any before!) I wonder if they are nascent balls of soredia. Also, I notice now that the soredia in the centre of the third image have joined together and have lost their separate ball-like appearances.
Many thanks for help and information.

synan's picture

Third image

The soralia in your third photo do look more plane than convex. It is probably the lumpiness of the thallus that lends them an elevated, rounded appearance in the overhead shots. I reckon the dark margin must be the prothallus, but perhaps it isn't often observed. I'll stick my neck out and say that, if anything, the flora needs updating, not your ID.

The black blobs don't seem to match the description of L. pannonica's apothecia, and are probably too numerous considering how rarely apothecia are seen. If they were nascent soralia, we might expect to see them on other photos, but that idea can't be ruled out. However, I'm leaning towards a parasitic fungus. If I'm right, microscopy would be needed to name it.

If your ID is correct, and I think it is, it looks like a new record for VC29.


pf339's picture


Thanks for thoughts and information. Much appreciated.