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Pseudocyphellaria norvegica chemistry

Posted: Fri Feb 14, 2020 9:05 pm
by Caz Walker
I have a specimen of what I'm pretty sure is Pseudocyphellaria norvegica collected in Argyll two weeks ago. Both in the field and back at home the chemistry of the medulla is consistent: C-, K+ pink or red, KC+ pale orange. According to Dobson this should be C+ red. I've tested mature very sorediate large lobes and smaller young lobes with similar results. This isn't the first time this has happened - P norvegica has been C- on other occasions. I assumed I'd done something wrong.

Theses reactions don't match any of the Pseudocyphellarias. Why do I think it's this genus? - underside covered in dark tomentum with indistinct pseudocyphellae, ruling out Nephroma which is bare and Sticta which has more distict cyphellae and no chemical reactions. I've checked that the bleach is OK - Punctelia subrudecta medulla shows red.

Has anyone any suggestions for the C- and K+ red reactions? Have I gone horribly wrong somewhere?

Thanks in advance
Caz Walker
P norvegica growing amongst bryophytes on outcrop
P norvegica growing amongst bryophytes on outcrop
It was very wet so the K+ red reaction spread out
It was very wet so the K+ red reaction spread out
K+ red reaction with KC+ orange reaction on the right
K+ red reaction with KC+ orange reaction on the right

Re: Pseudocyphellaria norvegica chemistry

Posted: Mon Feb 24, 2020 10:17 am
by Neil Sanderson

I had hoped that someone with more experience of these species would answer, but I remember finding the reactions to be a bit difficult between the species pair Pseudocyphellaria intricata and Pseudocyphellaria norvegica, but that was some time ago, and I can not quite remember what I was finding. Actually mature specimens are very different and can be distinguished by physical characters alone. Form the LGBI2:
Medulla C–, KC–; lobes elongate, surface ± smooth; soralia or isidia mostly marginal .................... intricata & lacerata

Medulla C+ red, KC+ orange-pink; lobes rounded; surface ± reticulately ridged;
soralia both laminal and marginal .................................................................................... norvegica
In mature specimens the thallus shape and soralia distribution are quite distinct but as the LGBI says under Pseudocyphellaria norvegica:
Immature material, with ± exclusively marginal soralia, may be easily confused with P. intricata; in such cases the KC+ orange, C+ red medulla is diagnostic.
The LGBI2 is incomplete in that it gives the full spot tests for Pseudocyphellaria intricata (Medulla and soralia C–, K+ yellow, KC–, Pd–, UV± bluish white) but not Pseudocyphellaria norvegica, but as far as I can construct from the text: medulla and soralia C+ red, K+ ?, KC+ orange, Pd–?, UV± brighter ice-blue)

NB of Pseudocyphellaria intricata the LGBI states that
Soralia farinose to coarsely granular-sorediate, whitish to grey-blue, predominantly marginal, subsequently becoming laminal remaining ± punctiform on older lobes
So Pseudocyphellaria intricata can have some laminal soralia on older thalli but these remain circular and do not elongate and extend as on mature Pseudocyphellaria norvegica

In the pictures of your specimen, the shape and soralia distribution look like Pseudocyphellaria norvegica and the spot tests are further from Pseudocyphellaria intricata than they are from Pseudocyphellaria norvegica.

I hope this helps


Re: Pseudocyphellaria norvegica chemistry

Posted: Mon Feb 24, 2020 8:46 pm
by Caz Walker
Neil, thanks for your reply. I agree that the reactions I had matched P norvegica better than P intricata and that the lobe shape and arrangement of soralia also look right for the former. As you say, no K reaction is given for P norvegica so the K+ shades of red is not categorically wrong. I don't have a UV torch so can't check that.

The distribution being strongly Scottish west coast precludes many people from seeing this species, therefore performing spot tests.

I still have the specimen so at some point I'll see what results someone else has with it.

Thanks again