Observation 80959: Peltigera Willd.
When: 2011-10-29
Who: zaca
No herbarium specimen

Proposed Names

31% (3)
Eye3
Recognized by sight
56% (1)
Eyes3
Recognized by sight

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Eye3 = Observer’s choice
Eyes3 = Current consensus

Comments

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Then you know more than many lichenologists! :)
By: Jason Hollinger (jason)
2011-11-05 23:44:05 EDT (-0400)

There’s another abstractly applicable quote: “If you think you understand quantum mechanics, you don’t.” (R. Feynman) I think that applies nicely to Peltigera, too! :)

Concerning Peltigera I’m reaching …
By: zaca
2011-11-05 18:00:28 EDT (-0400)

the formula of Descartes: ‘I know only that I know nothing’.

Wow! That is striking…
By: Jason Hollinger (jason)
2011-11-05 15:26:52 EDT (-0400)

Hard to believe these two observations are the same species, I agree! (Doesn’t mean they aren’t, though. :) In any case, I would consider P. monticola much more carefully for observation 78053 now that I see just how small-lobed it is. Sure wish I had access to a reference specimen. The only photo I find is a dark wet specimen by Eimy Rivas-Plata on CNALH.

finally, the photo with the comparison.
By: zaca
2011-11-05 14:49:24 EDT (-0400)
Before that I can do
By: zaca
2011-11-01 10:49:26 EDT (-0400)

the comparision that I promised, I had some pictures with a scale on them.

I also don’t feel very confortable with, …
By: zaca
2011-10-29 20:04:37 EDT (-0400)

what you call, oficial method. Because the size measured that way depends on the peace of thallus you consider. What I can say is that this specimen has bigger lobes that the one in MO78053, I would say almost twice, based on my memory. I have not the sample of the specimen in MO78053 with me right now, but when I’ll join the two I’ll take a photo. This probably will only be possible in one or two weeks time, but I’ll do it.

Official method of measuring lobe width…
By: Jason Hollinger (jason)
2011-10-29 19:40:23 EDT (-0400)

is far more ambiguous than I’d like. Is it at all possible Vitikainen measures it differently than you. Here is what Ernie Brodo says about it:

I personally completely ignore the absolute value. I’ve measured lobe width on specimens determined by experts – they never even come close to the reported widths. The values only even begins to make sense to me in relative terms. That is, I take a species I feel comfortable with, if it is reported to have 1-2 cm wide lobes, then I know monticola should have on average lobes half to a quarter as wide. In other words monticola is “very small” if praetextata is “normal size”. If you can get the actual numbers to work for you, my hat’s off to you!

The problem is that
By: zaca
2011-10-29 18:53:44 EDT (-0400)

in the small sample that I conserve with me all the lobes are greater than 3 cm wide and some even greater than 4 cm wide.

I might not be helping…
By: Jason Hollinger (jason)
2011-10-29 18:20:34 EDT (-0400)

Even the experts disagree on a regular basis, and we’re far from experts! I think, if anything, this and observation 64685 help verify our guess in observation 78053. As you say, the rhizines look a little different in the two. Based on this very sparse dataset, it seems plausible that 78053 is praetextata and the other two are ponojensis. It is also entirely possible (especially given how notoriously variable praetextata is) that all the above are praetextata.

As for monticola, hmmm… From Sonoran Flora:

P. monticola – lobes < 5 mm wide
P. rufescens – lobes < 10 mm wide
P. ponojensis – lobes 10-20 mm wide
P. fibrilloides – lobes 10-20 mm wide
P. praetextata – lobes < 30 mm wide

I wouldn’t be confident that there are no exceptions to this rule though!

I appreciate all the work based on my specimens.
By: zaca
2011-10-29 17:15:37 EDT (-0400)

I think that P. monticola must be ruled out, since the lobes have much more than 1 cm.

Between the species P. praetextata or P. ponojensis I can not choose, because this alternative has arisen regarding observation MO78053, whose specimen was very different from this one, in particular, the rhizines where very different. It seems that I’m a little confused by now …

I’ve changed my mind
By: Jason Hollinger (jason)
2011-10-29 14:28:32 EDT (-0400)

about this observation and observation 64685. MO has built up a fair selection of photos of this species by now, and notice how they are all very blistered, have strongly turned-down margins, and usually sparse/thin tomentum on the upper surface. But most importantly – this is how I was taught to recognize the species by the expert! – look at the veins and rhizines. Here’s a good example of P. membranacea (by Chris Parrish, of course!):

I’m thinking now that your two observations are either P. praetextata or P. ponojensis. (When in doubt always consider P. praetextata, haha!) I rule out P. rufescens because it should always have dark veins at least toward the center of the thallus, and more obviously confluent rhizines. Yours has pure white underside, and obvious raised veins (similar to membranacea), but the rhizines are mostly discrete. The confounding characteristic is the strongly squarrose quality of the rhizines. Note that membranacea has veins and rhizines covered with “tiny erect hairs”. These are very minute and give them a “soft” look (Chris’s photo demonstrates this excellently). But none of the photos on MO show membranacea with any squarrose branching like yours.

Looking at the key in the Sonoran Flora, I notice that there is a whole set of species which branch off of P. praetextata and P. ponojensis based on “richly branched rhizines”, including P. fibrilloides (lobes > 1 cm wide) and P. monticola (lobes < 1 cm wide). (I’m again ruling out P. membranacea and P. rufescens, the other two in that section of the key.) He (O. Vitikainen) claims that P. fibrilloides is exclusively in the Americas, but that P. monticola is found in Europe. It’s worth considering.

Created: 2011-10-29 11:08:01 EDT (-0400)
Last modified: 2014-03-24 14:06:32 EDT (-0400)
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