Observation 95818: Physconia enteroxantha (Nyl.) Poelt

When: 2012-05-06

Collection location: Parque de Monsanto, Lisboa, Portugal [Click for map]

Who: zaca

No specimen available

Growing on the bark of an old Quercus suber. The soredia accumulates at the margins of lobes and, in mature specimens, spread to cover the thallus centre. A peculiarity of the 1st specimen is that it is fertile (see the top of the first photo attached, mainly on the right), which is rare or very rare for the species P. enteroxantha, according to the references. The apothecia are different from what I’m used to see in other species of Physconia. I tryed to confirm this, searching the internet for images of fertile specimens of P. enteroxantha, with few success. I was only able to see apothecia in one of the Sharnoff photos (Nº 15) and these are similar shaped to those of mine and a bit darker. There were more specimens on the same tree, one with only one apothecium (see 2nd specimen) and the others unfertile (see 3rd and 4th specimens). In younger specimens the surfaces were slightly pruinose and the strong squarrose rhizines can be seen even from above.
The species P. perisidiosa, considered to be similar to P. enteroxantha, is also rarely fertile. Again, I was only able to see a fertile specimen in Sharnoff photos (Nº 4). The apothecia can be considered similar to those of P. enteroxantha.
Taken into account the color, the form and distribution of soredia, the chemical reactions and the underside of lobes I believe that these specimens belong to the species P. enteroxantha.


2nd specimen;
3rd speciemen;
4th specimen.

Proposed Names

62% (2)
Eye3 Eyes3
Recognized by sight: Yellow soredia; Underside brown/black, paler at margin; Squarrose black rhizines.
Based on chemical features: K+ bright yellow on soredia.

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
I think …
By: zaca
2012-05-30 14:22:07 PDT (-0700)

I understood your comment correctly and your vote accordingly. That’s out of question.
As you know I almost always present photos of (at least relevant) chemical reactions. I think this has the advantage of putting apart the questions of describing colors (often difficult to do) and strong/weak-ness of the reactions observed (maybe even more difficult to do). Therefore, I felt that an explanation for not presenting these reactions this time should be mentioned. This is the sense of my comment to your comment.
Let me add that I very much appreciate your comments and often learn much with them.

Didn’t mean to question the results, quite the opposite!
By: Jason Hollinger (jason)
2012-05-30 14:03:07 PDT (-0700)

I know people who only do the K test. I just personally find this unreliable. Sometimes you get concentrations so low that only KC will reveal yellow reaction. The comment should have read: “secalonic acid A must be particularly strong in these specimens”. Interesting by itself, I’m sure, but more to the point, it indicates that we can have high confidence in the result!

Let me make …
By: zaca
2012-05-30 13:45:20 PDT (-0700)

some comments to your comments:
1- “This looks like P. enteroxantha, especially 3 & 4”:
I think these (3 & 4) are the regular forms that one expect to see, young or moderate mature specimens. I believe that the first two specimens are very old, so that their center is almost all constituted by soredia and capable of developing fruit bodies. I also believe that the tree where they lived on is from the begining of the Park, that was reforested in 1940 (more or less).
2- “Interesting that K alone was enough to observe the secalonic acid A”:
This is not the all truth. As usual, I made all the spot test (but only on soredia, not on medulla). What happened is that the photos that I took, as I always do, were completely unfocused and of no value. Therefore, I only mentioned the reaction which seems to be relevant in this case. Moreover, I don’t remember if the yellow KC reaction was stronger than the K reaction alone.

I agree
By: Jason Hollinger (jason)
2012-05-30 12:36:58 PDT (-0700)

This looks like P. enteroxantha, especially 3 & 4

The apothecia look wet and poorly formed, so it doesn’t bother me that they are paler than usual. Andrew K. has come up with some rather pale-fruited specimens of other species of Physciaceae, so I know it can happen.

Interesting that K alone was enough to observe the secalonic acid A; usually I have to do KC do get a strong yellow reaction. (UV 375 nm will also reveal secalonic acid A, by the way, but less conspicuously than the KC test.)

Do also pay attention to where exactly you get the K/KC/UV+y reaction: P. leucoleiptes is very similar but only has secalonic acid A in the soralia, while P. enteroxantha has it throughout the medulla as well. The former was described in North America, so it might not be well-documented (or even known?) from Europe yet.

Created: 2012-05-30 11:49:08 PDT (-0700)
Last modified: 2012-05-30 12:30:19 PDT (-0700)
Viewed: 49 times, last viewed: 2017-09-29 03:15:24 PDT (-0700)
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