Observation 96825: Xanthoparmelia viriduloumbrina (Gyelnik) Lendemer
When: 2012-06-03
Herbarium specimen reported

Proposed Names

57% (1)
Eye3 Eyes3
Used references: ID provided by Jason Hollinger
57% (1)
Eye3
Used references: ID provided by Jim Bennett

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Eye3 = Observer’s choice
Eyes3 = Current consensus

Comments

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This specimen was already an admixture of three species, why not add a fourth!
By: Jason Hollinger (jason)
2015-12-24 19:14:20 PST (-0800)

The black web is an extremely common parasite on Xanthoparmelia species, Lichenostigma cosmopolites. Beautiful, isn’t it? But yes, extremely difficult to photograph. In one study I helped with in eastern Washington I estimate that roughly half of our Xanthoparmelia specimens was “infected” by this parasite. Infected might not be the right word, as it is almost superficial, inhabiting only the “epinecral” layer above the cortex — the layer of dead cells and sometimes exudate above the cortex. I don’t think it hurts the lichen at all, except in extreme cases where it must cover it sufficiently to starve it of light.

Concerning the host… The main difference between X. viriduloambrina and X. cumberlandia in the keys is stictic acid versus salazinic acid. Both are K+ yellow turning somewhere between orange and dark red depending on concentrations, and P+ yellow turning some shade of orangish yellow (weak salazinic acid) to deep orange (strong stictic acid). Very variable and subtle and ultimately unreliable without TLC. If Jim TLCed his specimen then trust his id over mine for sure. Of course, you might want to trust his anyway. ;)

(I don’t have a great deal of confidence in the current Xanthoparmelia taxonomy anyway. It won’t hurt my pride. ;)

Unknown structures on lichen.
By: Andrew Khitsun (Andrew)
2012-06-09 15:46:58 PDT (-0700)

These thallii are covered with a web of dark structures – hence the darkening of some areas of the lichen. At first I thought they were hairline cracks in the thallii. But under the microscope I realised they were convex ridges, not cracks at all. And they can be scraped off too. You can see the biggest of them in some of the photos, alongside with cracks that appear to be huge compared with these ridges. Unfortunately, I lack the magnification power needed to show them properly.
Otherwise, the lichen is non-isidiate, lower surface light-colored, medula K+ yellow changing to blood-red.

Created: 2012-06-09 15:31:46 PDT (-0700)
Last modified: 2015-12-24 17:43:42 PST (-0800)
Viewed: 54 times, last viewed: 2016-10-22 00:39:00 PDT (-0700)
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