Observation 117171: Punctelia perreticulata (Räsänen) G. Wilh. & Ladd
When: 2012-09-16
Herbarium specimen reported

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Jim Bennett returned ID P.perreticulata
By: Andrew Khitsun (Andrew)
2014-06-27 22:49:22 EDT (-0400)
I don’t know why P. borreri hasn’t been found in WI yet
By: Jason Hollinger (jason)
2012-11-19 00:38:00 EST (-0500)

It’s reported from MI, Ontario, Manitoba, Quebec, Minnesota, WV, VA, NC, MD. Weird. Definitely keep an eye out for it. It is C+/KC+r, sorediate, corticolous, but black below.

Sorry I didn’t mention lower surface (I didn’t know we might have P. borreri here)
By: Andrew Khitsun (Andrew)
2012-11-19 00:19:02 EST (-0500)

All specimen, including the one from the tree, have white lower surface. So it’s got to be P. perreticulata then, since pruina doesn’t mean much.

By: Jason Hollinger (jason)
2012-11-18 23:46:08 EST (-0500)

… were a mess. Lendemer & Hodkinson 2010 (in the Lichenologist) sequenced a bunch of specimens from both coasts and cleared it up a bit.

P. subrudecta apparently does not occur in North America.

P. caseana is the correct name for most eastern material with C+/KC+ medulla, pale lower surface and laminal (and some marginal) soralia. (They described this as a new species for North American material otherwise very similar to P. subrudecta. There are differences in conidia, I think, and maybe pruina.)

(P. jeckeri is the correct name for equivalent western material, differing primarily in being very faintly pruinose right at the growing margin of the lobe tips. This name already existed, but was not known to occur in North America.)

P. perreticulata is similar to all three of the above except: it has distinctly reticulate ridges throughout but especially in the older parts, and the soralia tend to be predominantly marginal (although laminal soralia do sometimes occur).

Apparently all of the above can be found on rock from time to time (but are primarily corticolous species).

I’d say the amazing specimen shown in the last two photos is definitely P. perreticulata (at least as I understand it).

The top one, though, I wonder. Does it look very reticulate near the margin to you? I’m wondering if it’s possibly P. borreri instead? Did you check if the lower surface was black by any chance? Isn’t P. borreri rugose/reticulate in the center sort of like this?

[EDIT: on further examination, I take it back, all the photos look like P. perreticulata to me. I don’t know that pruina is a critical character, and it can be very faint even if present, especially after rains.]

Did some tests:
By: Andrew Khitsun (Andrew)
2012-11-18 20:18:28 EST (-0500)

Medula K-, KC+ red, C+ red
Cortex K+?, KC-, C-
Using keys in Thomson, I arrived at P. perreticulata. But Thomson also has P. subrudecta that, if I understand correctly, was recently “exterminated”. Also, Thomson doesn’t have P. caseana. The latter is not supposed to have pruina, while P. perreticulata should. My specimens don’t have pruina, so they might be P. caseana
Most specimen were on sandstone bluffs, but I found one on nearby tree.

Created: 2012-11-18 19:28:38 EST (-0500)
Last modified: 2015-12-27 21:55:13 EST (-0500)
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