Chaenotheca trichialis?

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chriscant
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Chaenotheca trichialis?

Post by chriscant » Thu Apr 02, 2020 9:53 am

Caz Walker and I have been checking a specimen with our new-to-us microscopes.
It's a pin head lichen from a dry crack of a mature oak in Naddle forest by Haweswater Cumbria at head height.
Some of the pin heads have white pruina on the underside of the head and the top of the stalk.
The stalk is otherwise black and a bit shiny and the pin heads are a little brown.
The thallus is greenish and coarsely granular.
No K reaction.
There was Lecanactis abietina nearby on the tree.

We haven't calibrated the compound scope yet.
The pics are hopefully at the same scale.
The left section is the brown spores in water at 100x with oil.
The middle is the algae mass in K at 100x with oil
The right we think is free floating rounded rectangular green algae in water at 100x with oil.
I've superimposed one of the rightmost algae beside the spores.
We think this shows that an alga is 3x spore size, which is about right, we read, for Stichococcus.

We keyed this out as Chaenotheca trichialis. Does that look right?
Thanks in advance.
Attachments
IMG_20200401_124749 spore 100x oil 500px.jpg
IMG_20200401_140903 dissect 4x crop.jpg

Neil Sanderson
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Re: Chaenotheca trichialis?

Post by Neil Sanderson » Thu Apr 02, 2020 9:26 pm

Yes your algae is Stichococcus. I would need to see a better picture of the thallus to be sure of the identity of the Chaenotheca species. Typically the thallus Chaenotheca trichialis is quite blue-grey and almost squamulose, but it can be greener and more granular, and I can not quite make out what is going on in the picture. Chaenotheca trichialis is the most likely species and it looks much less Chaenotheca stemonea.

All the best

Neil
Neil Sanderson

chriscant
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Re: Chaenotheca trichialis?

Post by chriscant » Fri Apr 03, 2020 12:17 pm

Thanks Neil

I attach some more photos of our specimen, which looks quite granular to us, almost squamulose, and not farinose.
Let us know if there's any particular view which would help.

PS Are there any other algae that look like that Stichococcus? The drawing in LGBI2 would seem to indicate that there aren't.

Thanks again, Chris
Attachments
IMG_20200403_104608 crop.jpg
P4033727 crop.jpg
P4033727 resize.jpg

Neil Sanderson
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Re: Chaenotheca trichialis?

Post by Neil Sanderson » Sat Apr 04, 2020 9:59 pm

I can not be any more definite with those pictures, happy to have a look at the specimen.

As for algae, I suspect the LGBI2 was using a need to know basis; Stichococcus looks like nothing else associated with Chaenotheca species, so I have no idea if there are other algae that look similar, I hope someone else in the form does know.

Neil
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Chris Johnson
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Re: Chaenotheca trichialis?

Post by Chris Johnson » Sun Apr 05, 2020 6:59 am

Neil Sanderson wrote:
Sat Apr 04, 2020 9:59 pm
I can not be any more definite with those pictures, happy to have a look at the specimen.

As for algae, I suspect the LGBI2 was using a need to know basis; Stichococcus looks like nothing else associated with Chaenotheca species, so I have no idea if there are other algae that look similar, I hope someone else in the form does know.

Neil
The only other algae that come to mind is the genus Mesotaenium, a colonial desmid. They are usually found in muscilage and variable in length. The most common are M. chlamydosporum and M. macrococcum.
Attachments
Mesotaenium chlamydosporum
Mesotaenium chlamydosporum
Mesotaenium macrococcum
Mesotaenium macrococcum

chriscant
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Re: Chaenotheca trichialis?

Post by chriscant » Sun Apr 05, 2020 8:06 am

Thanks Neil - it would be nice to get it confirmed. I have an address of yours from an old survey document at Dibden - is that still right? Otherwise please send a private message.

Thanks Chris: that's useful. There's obviously a huge small world for us to explore.

PS I've improvised some calibration now and the spores were about 3μm and the algae ≈8μm.

Chris

Neil Sanderson
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Re: Chaenotheca trichialis?

Post by Neil Sanderson » Thu May 07, 2020 4:41 pm

Chris

Got the specimen now, there is a lot of free living algae on the specimen, which is what I was seeing in the photograph, but peeking out from under this are some very typical blue-grey corticate granules, so I am now 100% happy this is Chaenotheca trichialis.

Neil
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Re: Chaenotheca trichialis?

Post by chriscant » Sat May 09, 2020 11:09 am

Thanks!

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