Observation 111596: Melanelixia O. Blanco, A. Crespo, Divakar, Essl., D. Hawksw. & Lumbsch
When: 2012-09-29
Who: zaca
No herbarium specimen

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Of course,
By: zaca
2012-09-30 15:03:43 PDT (-0700)

and I have no better option for the classification of this specimen, in particular, I found no species of Melanohalea with these features.

Oh sure, I’m not criticizing
By: Jason Hollinger (jason)
2012-09-30 14:50:48 PDT (-0700)

Just explaining why I’m skeptical and continue to consider Melanelixia subaurifera a reasonable option.

You are right,
By: zaca
2012-09-30 14:42:06 PDT (-0700)

the spot tests were not done in the ideal conditions, but it was the best I could do at the moment.

I was agreeing with you
By: Jason Hollinger (jason)
2012-09-30 14:04:55 PDT (-0700)

that Melanelixia subaurifera varies from dull to shiny. Despite remembering it being only dull, I have seen at least one shiny specimen. And even though you think of it as being only shiny, your source claims it can vary between “matte and somewhat shiny”. All signs point to the same thing: shininess is not helpful in determining whether the present observation is M. subaurifera or not.

Chemistry should, however. Outside of the usual caveats that rare abnormal specimens will lack secondary substances, chemistry should be useful. I see M. subaurifera should have lecanoric acid. This should not be a subtle acid, as it usually produces a very strong and persistent C+ red. But I have noted a very weak and fleeting reaction on several occasions. (I noted C+ pink three times, C+ red three times, and failed to record the reaction 12 other times.)

I would not personally rule out the possibility of specimen with particularly weak lecanoric acid content from a photo of a few drops of bleach dumped on the thallus. But you well know by now that I habitually treat such photos with skepticism. I’ve been mistaken in my own spot tests too many times, and I apply reagents very carefully under a dissecting scope where I can see even the faintest and most fleeting reactions.

I don’t understand …
By: zaca
2012-09-30 13:47:53 PDT (-0700)

what’s your point, sorry.

Yup, and the one specimen I have a photo of…
By: Jason Hollinger (jason)
2012-09-30 13:42:37 PDT (-0700)

… is clearly shiny! Haha. Yeah, so it clearly varies in how shiny it is, both sides of the ocean.

Maybe not.
By: zaca
2012-09-30 13:21:46 PDT (-0700)

I remember to see a description where it is said “thallus matt to somewhat shiny”, but naturally I recall what I’ve seen.

Interesting
By: Jason Hollinger (jason)
2012-09-30 12:07:54 PDT (-0700)

I generally think of it being a dull species, not shiny. Yet another difference between European and American material?

Yes, maybe “moderate shiny” is a better description
By: zaca
2012-09-30 11:52:45 PDT (-0700)

(see, e.g. observation 88872).

Do you mean
By: Jason Hollinger (jason)
2012-09-30 11:37:12 PDT (-0700)

the specimens of Melanelixia subaurifera you’ve seen were shinier than this one?

Yes, it looks like Melanelixia subaurifera,
By: zaca
2012-09-30 08:35:41 PDT (-0700)

though the specimens I found so far were more shiny. I ruled it out based on the chemistry.

I think this looks like Melanelixia subaurifera
By: Jason Hollinger (jason)
2012-09-29 23:32:02 PDT (-0700)

It’s a northern group (Melanelia s. lat.), so there’s every reason to believe all of your species will be covered in the British Flora. But then again I can’t explain the C- KC- tests.

Created: 2012-09-29 14:17:02 PDT (-0700)
Last modified: 2012-09-30 15:04:22 PDT (-0700)
Viewed: 101 times, last viewed: 2016-10-22 15:25:03 PDT (-0700)
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