Observation 87905: Porpidia crustulata (Ach.) Hertel & Knoph
When: 2011-05-11
No herbarium specimen

Proposed Names

34% (2)
Recognized by sight
56% (1)
Recognized by sight: see Andrew’s and Chris’s comments

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Eye3 = Observer’s choice
Eyes3 = Current consensus


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I’m appeased
By: Jason Hollinger (jason)
2012-02-20 11:20:00 PST (-0800)

So long as the voting makes it clear this is just an educated guess!

I suspected those three too.
By: Andrew Khitsun (Andrew)
2012-02-19 21:26:57 PST (-0800)

I just didn’t know if there are more species to consider. Since there seems to be none, process of elimination will help to get (tentative) ID. Of course, no picture will replace spore under microscope (I’m trying to appease Jason:-). Both Rhizocarpon concentricum and Porpidia macrocarpa seem to be restricted to Canadian Zone in the northern WI, and P.macrocarpa also seem to look slightly different with its larger apothecia. Porpidia crustulata, on the other hand, is pretty common here, so I’ll tentatively call it that.

the usual suspects
By: Chris Parrish (kitparrish)
2012-02-19 19:34:28 PST (-0800)

abundant black, lecidine apothecia arranged in concentric circles on a thin grayish-white thallus (data from Brodo et al., 2002; Thompson, 1997, “American Arctic Lichens,” vol. 2, pp.527-530; Gowan, 1989):

Porpidia crustulata apothecia to 1.5 mm diameter, sessile but sometimes sunken into thallus; spores simple; 458 CNALH records
Porpidia macrocarpa apothecia to 3.5 mm diameter, sessile or sunken in thick thallus; spores simple; 303 CNALH records
Rhizocarpon concentricum apothecia to 1 mm diameter, immersed in thallus; spores muriform, hyaline with halo; 22 CNALH records

In all three cases, the CNALH records include specimens from overseas.

Are there other species to add to the list?

Gowan, Sharon P., 1989, The Lichen Genus Porpidia (Porpidiaceae) in North America, The Bryologist, Vol. 92, No. 1 (Spring, 1989), pp. 25-59

Sharnoff’s Porpidia crustulata gallery
Sharnoff’s Porpidia macrocarpa gallery
Wikimedia Common’s Rhizocarpon concentricum gallery

CNALH Porpidia crustulata gallery
CNALH Porpidia macrocarpa gallery
CNALH Rhizocarpon concentricum gallery

You could be right
By: Jason Hollinger (jason)
2012-02-18 15:08:47 PST (-0800)

I will remain skeptical until I’ve had the opportunity to verify more specimens. Sorry, don’t let me rain on your parade! I’ve just gotten so many things wrong I’m finally learning to keep my mouth shut in cases like these. :)

Circular pattern?
By: Andrew Khitsun (Andrew)
2012-02-18 14:53:55 PST (-0800)

I might be wrong, but it seems there are few species that develop this circular pattern, and the rest of the bunch just have black apothecia scattered around the thallus, where thallus can be roundish in shape or otherwise. For example, my observation 87862 doesn’t have apothecia forming rings within thallus.

Very possible
By: Jason Hollinger (jason)
2012-02-18 10:58:57 PST (-0800)

Just let me encourage a healthy skepticism for these black-button crusts without microscopy.

Porpidia crustulata?
By: Andrew Khitsun (Andrew)
2012-02-17 16:19:09 PST (-0800)

Or Rhizocarpon concentricum? The latter has only so far been found in the northern part of the state.

Created: 2012-02-17 16:15:33 PST (-0800)
Last modified: 2012-02-20 11:21:20 PST (-0800)
Viewed: 76 times, last viewed: 2016-10-27 08:28:34 PDT (-0700)
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