Observation 113992: Lichen P. Micheli
When: 2012-10-21
No herbarium specimen

Notes: Substrate: bark of Lizyphus mistol.

Thallus: foliose light green up to 3cm+ in diameter, sorediated margins.

Proposed Names

83% (1)
Eye3 Eyes3
Recognized by sight
28% (1)
Used references: “Identification of Urban Lichens in the Field: A Case Study for Buenos Aires.” Scutari, N., and N. Theinhardt. Mycotoxin Fall, 2001, p.427-445.
28% (1)
Recognized by sight

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Eye3 = Observer’s choice
Eyes3 = Current consensus

Comments

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There’s a mess of possibilities, no question!
By: Jason Hollinger (jason)
2012-10-21 13:51:13 CDT (-0500)

P. lacinulata is a good idea. I’d dismissed it, but looking closely at the center of the first and last photo, and I agree, you may have a point. Don’t forget that you may have multiple species here. Testing the medulla of each has to be first priority. (And be careful not to read a false K+y on the medulla from the result of the cortex bleeding in.) Then examine them carefully for pruina and the exact kind of soralia present. In a group this close, keep in mind that if you want anything like certainty, there is no alternative to getting professional verification. I would personally also check careful sections the upper and lower cortex at 400x, as well. The gross characters are too variable and ambiguous to rely on them 100%. You want as much data as possible.

One more note: Up close there is a distinct qualitative difference between the Physcia-like Heterodermia (like H. albicans) and true Physcia. Heterodermia has a different kind of cortex, with elongate hyphae running ~lengthwise. This results in a “flowing” appearance. Compare:

H. albicans:

P. undulata:

Table for Physcia species in Buenos Aires region….
By: nastassja (Nastassja Noell)
2012-10-21 12:00:07 CDT (-0500)
P. crispa P. undulata P. sinuosa H. albicans P. poncinsii
Upperside sky-blue grayish, farinose grayish-green smooth
Epinecral layer absent present absent absent
Pruina dull, farinose absent occasional, dull, fine
Medulla K- K+citrine yellow K+reddish to red
Soralia marginal (lateral), linear, short marginal (axilar), hemiorbicular marginal, linear laminal, crateriform
Margins of lobes crisped undulate (upper cortex revolute)

As I’m making this table I’m seeing what you are saying with Physcia undulata — the frosted epinecral layer making a bluish tinge of upperside seems to fit well…

And I’m also finding something way interesting… that maybe there is phyllidia at the center, particularly in the first photo? I had no idea what phyllidia were before reading this B.A. key so maybe I’m just over excited and want to see them in the specimen, but there’s a pretty good picture that kinda a bit matches here and if that’s the case, then this could be….

Physcia lacinulata — Thallus with soralia and/or phyllidia; soralia marginal, punctiform, undulate to linear, and or laminal, punctiform to orbicular, phyllidia marginal and/or laminal…

Does soralia look punctiform to orbicular? I’m not so good as seeing that kind of difference…

Other options
By: Jason Hollinger (jason)
2012-10-21 01:35:15 CDT (-0500)

Good idea looking at the urban case study paper! Have to go back to the Parmelioid thing again. But this one can be several things, unfortunately: in addition to Physcia crispa also check Physcia undulata and Heterodermia albicans. (It look very similar to a specimen of P. undulata J. Lendemer verified for me from the Florida Keys.)

Created: 2012-10-21 00:23:25 CDT (-0500)
Last modified: 2012-10-21 01:35:55 CDT (-0500)
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