Observation 75356: Parmotrema A. Massal.
When: 2011-09-03
Who: zaca
No herbarium specimen

Proposed Names

5% (2)
Eye3
Recognized by sight
Based on chemical features
28% (1)
Eyes3
Recognized by sight: in the hypoleucinum group

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Eye3 = Observer’s choice
Eyes3 = Current consensus

Comments

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Yes,
By: zaca
2011-09-05 11:47:47 PDT (-0700)

the first species you mentioned, P. hypoleucinum, appears in the portuguese checklist.
Concerning the chemical reactions, some orangish tons appeared after some time in the K+y, 2nd and 3rd photos.
Thanks, Jason.

Much better!
By: Jason Hollinger (jason)
2011-09-05 11:34:45 PDT (-0700)

Yes, now it’s absolutely clear that the medulla is K+y darkening a bit over time, typical of stictic acid, possibly with traces of norstictic acid.

(I’ve seen species in several genera that are supposed to have norstictic acid as a major substance but which nevertheless only react K+y to maybe a bit orangish. I’ve even gone so far as to look at them under a microscope where norstictic acid produces these cool needle-shaped crystals in KOH, but these same specimens show no crystals even after a few minutes. I guess the moral of the story is that norstictic acid can sometimes be undetectable by ordinary means. Salazinic acid, on the other hand, seems to be more reliable.)

So, even though the Sipman key shows no species in this group which react only K+y, I would still say you’ve got either P. hypoleucinum or P. hypotropum. The ranges mentioned (both are allegedly restricted to Mexico) are dead wrong. In fact, I’d say ignore the ranges throughout the keys. Unfortunately these two species are indistinguishable without TLC, or so I’m told. Are either species reported for Portugal?

Many thanks, Jason, for all these explanations.
By: zaca
2011-09-05 11:18:50 PDT (-0700)

I Already uploaded a photo with the new chemical tests. I not sure this is helpful, but … we never know.

It’s a tough genus, no question!
By: Jason Hollinger (jason)
2011-09-04 19:44:13 PDT (-0700)

But it’s mostly just difficult to describe in words. Once you see material from all the groups it really makes much more sense than it does at first. I don’t know if this will help, but (some of) the major groups are:

1) finely cracked surface (generally very ciliate and ruffled) — P. reticulatum, P. subisidiosum, P. cetratum, etc. (once known as Rimelia)
2) conspicuous broad white zones near margins below (very ruffled and crisped) — P. hypotropum, P. hypoleucinum, P. perforatum, etc.
3) ~brown below with rhizines of two different length running all the way to the margin (typically not very ruffled) — P. subtinctorum, P. neotropicum, etc. (once known as Canomaculina)
4) the rest :) — (ruffled, black below, no rhizines near the egde, evenly colored smooth cortex, cilia present or not)

These are difficult groups to describe, but they’re immediately recognizable by “gestalt”. Worth getting to know them. Sipman relies on them heavily in his key, too.

As for my comment on spot test: I don’t know how to interpret the colors I see in your photo, especially the K and KC. It’s clearly C-, and the cortex looks K+y, but I can’t tell if the golden color on the medulla is from the cortex reaction or if there’s a separate K+y in the medulla. In fact it may even potentially be K+ orange in the medulla, I just can’t tell. I would expect the KC spot to be clear not yellow/orange, no matter what the K reactions. KC should clear K+y from atranorin and things in the stictic/norstictic/salazinic acid group. It’s just confusing. If I saw this on my own specimen, I’d start fresh, scrape the cortex off a nice broad area to avoid any possible contamination from cortex, and apply less reagent, maybe even get fresh bleach as well, to make absolutely sure my C hasn’t become too weak.

But I read about other people doing tests this way and apparently interpreting them just fine. I just don’t get it myself, what can I say? Everyone has their preferred method of doing spot tests, I guess! :)

I definitely …
By: zaca
2011-09-04 16:01:51 PDT (-0700)
do not understand anything about Parmotrema!

In this case seems to be the existence of white spots on the underside of the thallus …
As for chemical reactions, I do not understand your comment. If necessary I will repeat them, because I still have the stuff.
In the field, the silver gleam of this specimen (a little less in the specimen of the other observation) was something that I had not yet seen. This has some particular significance?
Thank you, Jason, for your help once again.

This is one of the group with white zone near the margin
By: Jason Hollinger (jason)
2011-09-04 11:46:26 PDT (-0700)

See leads 88 to 90 in Sipman’s key
I rely 100% on chemistry to separate these, but I don’t know how to interpret your chemistry. (It’s so much easier if you’re the one doing the spot tests, unfortunately.)

Created: 2011-09-04 03:01:49 PDT (-0700)
Last modified: 2011-09-05 11:19:46 PDT (-0700)
Viewed: 67 times, last viewed: 2016-04-26 08:37:55 PDT (-0700)
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