Observation 69768: Physcia tribacia (Ach.) Nyl.
When: 2011-05-29
No herbarium specimen

Notes: Locality: Rhyolite Canyon

Substrate: Rhyolite boulder

Proposed Names

-28% (1)
Recognized by sight
28% (1)
Eye3
Recognized by sight: lobes long and narrow, thallus small and fertile, without soredia or isidia, growing on rhyolite boulder in canyon bottom
Used references: Moberg in Nash et al., 2002, vol. 1, pp.358-373
31% (2)
Eye3 Eyes3
Recognized by sight

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Eye3 = Observer’s choice
Eyes3 = Current consensus

Comments

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We’ll show them!
By: Jason Hollinger (jason)
2012-02-26 16:34:40 PST (-0800)

MO photos usual enjoy high ranking. We’re doing our part to fix the errors on the web. (Okay, yes, we do spread more than our fair share of misinformation based on pure guesswork ids, too, but let’s not talk about those. It’s google’s fault for not checking confidence levels before indexing our photos! And unlike other sites, we welcome all and sundry to come and debate our ids. So there.)

Thanks, Jason!
By: Chris Parrish (kitparrish)
2012-02-26 16:07:34 PST (-0800)

This observation pretty clearly belongs alongside yours from Southern California and the Sharnoff photo from the Coast Range of California attributed to Physcia callosa in Brodo.

If we trust Ernie Brodo…
By: Jason Hollinger (jason)
2012-02-26 15:57:42 PST (-0800)

Look at the difference between the photos in Lichens of North America for P. halei and P. callosa (= P. tribacia).

I just posted some photos of material I’ve been calling P. tribacia from southern California. Note that P. halei is essentially unknown in southern California, so there’s no way this very common thing can be that. (See observation 88274.) I found a lot of fertile populations at that location.

By: Chris Parrish (kitparrish)
2012-02-26 15:45:24 PST (-0800)

Thanks, Jason! Andrew’s great series of Physciaceae observations prompted me to go back and have another go at trying to identify this distinctive lichen from Chiricahua National Monument.

I still have the Sonoran Flora and numerous web pages spread out in front of me. Here are the notes I’ve just taken:

According to a recent CNALH online dynamic checklist, eight species of Physcia are known to occur on rocks within 60 miles of this well-known locality:

sorediate Physcia: adscendens, caesia, erumpens, sorediosa, tribacia

fertile Physcia:
Physcia halei lobes long and narrow, " … up to 1 mm wide, margins mostly crenulate; … a relatively common species at intermediate elevations in Arizona" with numerous CNALH records throughout the Chiricahua Mountains, including Chiricahua National Monument.
Physcia biziana lobes distinctly widening and slightly ascending at tips
Physcia phaea upper surface strongly maculate and rugose

On the one hand, CNALH say “Physcia halei is the fertile counterpart [of Physcia tribacia] and, except for the lack of soralia, differs by having longer lobes,” but on the other hand, apothecia are “uncommon” on Physcia tribacia (CNALH page for Physcia tribacia). CNALH locality records indicate that both species are evidently common throughout the Chiricahuas and in the national monument.

So it seems the crux of the matter lies in whether or not there are soralia lying under those tiny lobe tips.

References:
CNALH page for Physcia halei
CNALH page for Physcia tribacia

I’ve been calling this sort of thing P. tribacia
By: Jason Hollinger (jason)
2012-02-26 15:26:16 PST (-0800)

But look at the photos attributed to this species on the web: they’re all over the board, from things like this with soredia hidden under weird tapering “ugly” tips, to things with broad tips and labriform soralia more reminiscent of Physconia detersa. I don’t know who to believe any more. Whatever it is, it is one of the most common rock-dwelling species of Physcia in the southwest. It is locally abundant in the Santa Monica and San Grabriel mountains in southern California. And I’ve seen it in Arizona and New Mexico, too.

Created: 2011-06-20 17:34:20 PDT (-0700)
Last modified: 2012-02-26 16:03:45 PST (-0800)
Viewed: 78 times, last viewed: 2016-11-27 07:15:06 PST (-0800)
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