Observation 97114: Physcia dubia (Hoffm.) Lettau

When: 2012-06-03

Collection location: Governor Dodge State Park, Wisconsin, USA [Click for map]

Who: Andrew Khitsun (Andrew)

Specimen available



Proposed Names

57% (1)
Recognized by sight
61% (2)
Recognized by sight: see comments

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
By: Jason Hollinger (jason)
2012-06-12 19:57:54 CDT (-0400)

I think you’ve got it. Whee! How exciting when things finally fit into place.

Perhaps more of the same…
By: Andrew Khitsun (Andrew)
2012-06-12 18:42:04 CDT (-0400)

If this is P.dubia, then it takes care (maybe) of the “mystery” small Physcia with upturned lobes depicted in observation 88246 and also in observation 87955 (bottom photos, coexisting with P.subtilis)

By: Andrew Khitsun (Andrew)
2012-06-12 18:25:42 CDT (-0400)

Thanks a lot. I’ve never seen P.dubia before but now, comparing with the photo you’re referring to (and half a dozen others), I see it must be it. Mine looks exactly like that under the microscope – labriform soralia, upturned lobe tips etc. Just wanted to confirm the K test left both cortex and medula stained permanently green. Also, the species is in the list for Iowa county where the park in question is.

By: Jason Hollinger (jason)
2012-06-12 02:02:21 CDT (-0400)

I’m not too concerned about the cortex having a weak K+y. The medulla should, however, be clear if it were K+. That leaves P. millegrana (but I agree with you), and P. dubia. It’s promising. See this photo, for example.

Just tested
By: Andrew Khitsun (Andrew)
2012-06-11 22:15:53 CDT (-0400)

K test left permanent staining of both medula and cortex, but I’d struggle to call the color yellow. It’s greenish, similar to when the lichen is wet.

By: Jason Hollinger (jason)
2012-06-11 22:07:48 CDT (-0400)

Could it be P. subtilis? K tests in medulla and cortex would help, but might need to check cellular structure of upper and lower cortices to be sure(!)

Just spacing out…
By: Andrew Khitsun (Andrew)
2012-06-11 21:18:59 CDT (-0400)

Lower surface white with white rhizines
On the other hand, looks like Physcia millegrana, except I’ve never seen rosette this perfect.

Created: 2012-06-11 21:15:28 CDT (-0400)
Last modified: 2012-06-12 18:32:07 CDT (-0400)
Viewed: 78 times, last viewed: 2017-07-31 11:48:44 CDT (-0400)
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