Baeomyces lichen help

[diggleken]

Hi all, after striking lucky with a couple of ID's recently, this has me back down to earth, need help!
Its pinkish on green, so is it Baeomyces roseus or Icmadophila ericitorum perhaps?
It was on open moorland dampish rocks and doesnt appear to have a stem.
Grateful for a steer!
Cheers
Ken

[AlanS]

Originally Posted by diggleken

Hi all, after striking lucky with a couple of ID's recently, this has me back down to earth, need help!
Its pinkish on green, so is it Baeomyces roseus or Icmadophila ericitorum perhaps?
It was on open moorland dampish rocks and doesnt appear to have a stem.
Grateful for a steer!
Cheers
Ken

It seems to me, Ken, that you are still on a roll - you have correctly narrowed it down to two that relatively experienced lichenologists sometimes get confused.

This is Icmadophila ericetorum - typical material with flattened-convex apothecia (usually) lacking stalks, arising from a strongly green-grey crust.

In Dibaeis baeomyces (= Baeomyces roseus) the apothecia are globular, on well-developed, stout stalks, and the crust may be green but is more often white. It is quite common on moorland banks but much more rarely fruits (though, inevitably, books always choose a photo of it in fruit.)

A trap for the unwary is that apothecia of Icmadophila can also be distinctly stalked and, contrary to a statement in Dobson, mushroom-shaped (as distinct from globular) apothecia are more likely to be Icmadophila. When in doubt, the thallus of Icmadophila is bright blue-white under a UV light, such as a bank-note checker, whereas Dibaeis is convincingly bright orange.

Alan

[diggleken]

Brilliant, thanks a lot Alan.
My little book (Oxford flowerless plants) has Icmadophila ericetorum on decaying turf and rottng wood on moors, partic in scotland, which is what threw me as it was on rock, but I'm sure that the description would generally be right in most cases.......................but not this!
I guess there may be some underlying very thin such rotting substrate though.
I think I need another lichen book.
Cheers
Ken

[AlanS]

Originally Posted by diggleken

I guess there may be some underlying very thin such rotting substrate though.

Yes, I am sure you are right.

I saw some superb sheets of Icmadophila on wet rocks up in Sutherland last summer. There was a peat layer on top of the rock, and peaty water was regularly washing down, providing enough nutrition for the Icmadophila.

This acid flushing was too much for some of the more typically rock-face lichens.

Alan
(resisting the urge to moan about rain, midges, more rain, more midges, and even more midges)