Observation 88737: Xanthoparmelia cumberlandia (Gyelnik) Hale

When: 2009-03-31

Collection location: Madison, Wisconsin, USA [Click for map]

Who: Andrew Khitsun (Andrew)

No specimen available

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Eye3 = Observer’s choice
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Jim Bennett confirmed X.cumberlandia/X.plittii mix
By: Andrew Khitsun (Andrew)
2015-03-07 20:54:29 CST (-0600)
Isidia or not isidia
By: Jason Hollinger (jason)
2012-04-24 15:50:43 CDT (-0500)

It is a fundamental tenant in lichenology that all thalli except when very young will display soredia or isidia if they are ever going to. Apothecia are more variable: isidiate and sorediate species often have a few apothecia; non-isidiate, non-sorediate species often have no apothecia. But non-isidiate, non-sorediate species never have isidia or soredia. (Phyllidia / lobules are another matter.)

Therefore, if you follow the official canon, observation 88767 can only be interpreted as a mix of two species: Isidia are definitely present, so plittii must be present. But there are vast stretches of thallus without any isidia, and plittii would never do this. If it can produce isidia, it will.

I don’t know to what extent this fundamental set of assumptions has been tested, though.

By: Andrew Khitsun (Andrew)
2012-04-24 15:18:23 CDT (-0500)

Strange thing – I have this large colony of the lichen that look very much alike. Some of the thallii don’t have any isidia, some are very isidiate, and some have isidia only on the portion of the thallus. If you look at the observation 88686 – it’s all isidiate, the observation here doesn’t have any, and observation 88767 shows only some isidia at the bottom of the first and second photo. All have pale to brown lower side, and respond to K test identically – yellow first, sometimes changing to orange later on some medula. I wonder if the whole lot is actually X.plittii, but some have no isidia. Otherwise I have a mixture of X.plittii and X.cumberlandia. On the other hand, even isidiate specimens have plenty of pycnidia, which X.plittii is not supposed to have (or rare).

Sorry, no help
By: Jason Hollinger (jason)
2012-04-23 23:35:53 CDT (-0500)

I just know how to read spot tests. I can’t venture any useful opinions on the variation of these species! (Or validity of them, for that matter, something under debate presently…) Keep identifying these correlations. You may be onto something, despite what the spot tests say, at least in your area.

By: Andrew Khitsun (Andrew)
2012-04-23 21:45:11 CDT (-0500)

I’ll grab more thallii, just to double-check. Any other ways to distinguish the two – C, P, I or other chems? I can look in the books, of course, but I trust you more since different books offer up different results :-)

Uncooperative spot tests
By: Jason Hollinger (jason)
2012-04-23 17:09:42 CDT (-0500)

Just looked up X. cumberlandia (see Sonoran Flora or identical description on CNALH) and X. viriduloumbina (see Harris & Ladd 2005, Ozarks Flora, and Lendemer 2005, Mycotaxon 92:441-442). X. viriduloumbrina (X. somloënsis in Thomson Flora) has salazinic acid major; X. cumberlandia has stictic acid major along with constictic and norstictic acid both as minor substances.

I think this is the key. While norstictic minor can cause the K test to turn bright red after a while, especially if your KOH is very strong, it can also be invisible, leaving the K test just deep yellow. Salazinic acid, on the other hand, always invariably turns blood red rapidly.

My conclusion based on the K test remaining yellow is that this must be X. cumberlandia despite the apparently atypical form. (I have to trust you there, I haven’t built up any intuition for this sort of thing yet.)

Lower surface pale, K+
By: Andrew Khitsun (Andrew)
2012-04-22 20:09:42 CDT (-0500)

I just examined fresh specimen, and I think it’s more likely to be X.viriduloumbrina, since X.cumberlandia is usually more appressed. The other difference between them should be how fast (or slow) medula turns from yellow to orange/red with K test. The problem with mine – it didn’t at all – medula stayed lemon-yellow when K was applied.

Created: 2012-03-06 17:27:02 CST (-0600)
Last modified: 2015-12-14 21:14:20 CST (-0600)
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