Lichen ID please

[Tiggrx]

I've decided that I'm not that great at identifying lichen. I flicked through all the pictures in the book and cannot find a match for this one.

It was growing on rocks on the upper shore zone in Jersey

thanks for any help
Aaron

[AlanS]

Hi Aaron,

I have puzzled over this since you posted it and I am still puzzled. The main part of the lichen looks like Ochrolechia parella, though not too healthy.

But no Ochrolechia has that yellow component. Lichens often have a differently coloured prothallus, an initial colonisation stage that continues around the edge of a colony, but I don't know of any white lichen that has a yellow prothallus. It seems to me that the yellow must be another lichen, most likely a Caloplaca, or possibly a Leproplaca, but if so, what is going on? Is one lichen taking over from another, trying to steal its algae? But Caloplaca and Ochrolechia have different photobionts. Are they both competing for a space that happens to exist within the Verrucaria maura colony (the black lichen)?

I dunno. It's all part of nature's dynamics.
(Well, it's the sort of answer students usually accept.)

Alan

[Tiggrx]

Thanks Alan,

it's makes me feel a bit better that it wasn't something simple

Is O. parella a typical upper shore lichen - it doesn't mention that as a habitat for it in my book (Dobson) - I thought it would have been a fairly specialist habitat.

I'm suprised anything managed to find any space amongst all the Verrucaria!

Originally Posted by AlanS

Hi Aaron,

I have puzzled over this since you posted it and I am still puzzled. The main part of the lichen looks like Ochrolechia parella, though not too healthy.

But no Ochrolechia has that yellow component. Lichens often have a differently coloured prothallus, an initial colonisation stage that continues around the edge of a colony, but I don't know of any white lichen that has a yellow prothallus. It seems to me that the yellow must be another lichen, most likely a Caloplaca, or possibly a Leproplaca, but if so, what is going on? Is one lichen taking over from another, trying to steal its algae? But Caloplaca and Ochrolechia have different photobionts. Are they both competing for a space that happens to exist within the Verrucaria maura colony (the black lichen)?

I dunno. It's all part of nature's dynamics.
(Well, it's the sort of answer students usually accept.)

Alan

[AlanS]

Originally Posted by Tiggrx

Thanks Alan,

it's makes me feel a bit better that it wasn't something simple

Is O. parella a typical upper shore lichen - it doesn't mention that as a habitat for it in my book (Dobson) - I thought it would have been a fairly specialist habitat.

I'm suprised anything managed to find any space amongst all the Verrucaria!

O. parella is generally common on siliceous rocks and I saw a lot of it quite low down on coastal rocks last week while I was doing some higher-plant vice-county square bashing. However I think it is a bit out of place down in the Verrucaria zone and I am reasoning that this is why it looks unhealthy in your photograph and apparently in competition with a Caloplaca. Higher on the shore it seems to pretty well out-compete anything!

Someone may still suggest another ID possibility of course.

Alan