Observation 96287: Pleopsidium flavum (Bellardi) Körber

When: 2012-06-03

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

Who: Andrew Khitsun (Andrew)

No specimen available

Proposed Names

2% (2)
Recognized by sight
2% (2)
Recognized by sight
2% (2)
Recognized by sight: It’s fairly common in the “driftless” part of the state and is listed in Iowa County where this park is located
61% (2)
Used references: ID provided by Jim Bennett (distinguished from P.chlorophanum by apothecia)

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Eye3 = Observer’s choice
Eyes3 = Current consensus


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Jim Bennett returned ID Pleopsidium flavum
By: Andrew Khitsun (Andrew)
2014-11-09 10:40:52 CST (-0600)
Beautiful location
By: Jason Hollinger (jason)
2012-07-17 00:26:51 CDT (-0500)

I can see now why you’re finding such good material.

I’m cheating.
By: Andrew Khitsun (Andrew)
2012-07-16 20:17:46 CDT (-0500)

I added few photos. Technically, they were taken several days later. But it’s the same park and very close to the first location – just the next bluff over. And I wanted to show how they grow – on vertical cliffs, so the best patches are totally inaccessible. This lichen knows how to avoid paparazzi.

They aren’t well-developed on these specimens
By: Jason Hollinger (jason)
2012-06-04 16:42:20 CDT (-0500)

Because of competition and physical damange, I think. But you can see it very clearly here and there. See just below center in image 224408, for example. There’s no other interpretation of that margin. Effigurate species can lack the character if damaged, but non-effigurate species will never “accidentally” show an effigurate margin anywhere!

There’s not even a mention of Pleopsidium under Acarospora in the Sonoran Flora, and under Pleopsidium this is all Knudsen has to say on the subject:

Because there are at least two effigurate, yellow Acarospora, A. erythrophora (C+ thallus and apothecia) and A. novomexicana, one should not assume that every yellow placodioid specimen is a Pleopsidium. In Acarospora the ascus tholus is K/I-.

British Flora gives little more:

Acarospora differs in the Acarospora-type asci, paraplectenchymatous upper cortex [blocky cells instead of elongate hyphae] and absence of rhizocarpic acid [UV+ orange].

Brodo has even less to say.

[Note: Both effigurate yellow Acarospora also contain rhizocarpic acid, so the UV test is useless in North America. However, while some Acarospora don’t have paraplectenchymatous cortices (contrary to the implication in the British Flora), the yellow effigurate ones do, so that character is useful in our case… if you are willing to do a “scalp” section of an areole and examine it at 1000×.]

Conclusion: we can’t even be sure of the genus without doing an ascus stain. C test will, however, rule out one of the Acarospora. We’ll just have to trust Bennett that A. novomexicana isn’t present. (Although note that Harris claimed it was present in the Ozarks, not so very far south of you…)

Pleopsidium chlorophanum
By: Andrew Khitsun (Andrew)
2012-06-04 16:15:48 CDT (-0500)

Jim Bennett reports P.chlorophanum from Iowa County (that’s where this park is located). I just didn’t consider Pleopsidium since I thought that genus has more lobes on outer edges of thalli.

Reconsidering Pleopsidium
By: Jason Hollinger (jason)
2012-06-04 04:15:06 CDT (-0500)

Looking more closely, I see now that these really are effigurate where they haven’t been damaged, making Pleopsidium more likely. Not easy to distinguish the two species: P. flavum has smaller, yellower, flatter apothecia (< 0.6 mm wide); P. chlorophanum has larger, oranger, more convex apothecia (1-3 mm wide). Jim Bennett reports both from the state.

There are very few reports of yellow Acarospora from Wisconsin
By: Jason Hollinger (jason)
2012-06-04 04:09:07 CDT (-0500)

It would be nice to verify if it is C+ or C-. The only name in Thomson’s flora is A. chlorophana, but that’s an old name that was mistakenly used for all yellow effigurate species in North America. The list you sent me from Jim Bennett only includes A. schleicheri, but that’s a terricolous species which looks rather different. Ozarks flora lists a few species; CNALH have a few reports of various yellow species, too. Some options are A. erythrophora, A. heufleriana (both C+), A. novomexicana, A. contigua and A. socialis (all C-).

Created: 2012-06-03 20:42:20 CDT (-0500)
Last modified: 2014-11-10 09:00:49 CST (-0600)
Viewed: 105 times, last viewed: 2017-06-13 01:55:12 CDT (-0500)
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