Observation 218327: Physconia enteroxantha (Nyl.) Poelt
When: 2015-09-16
(35.7569° -120.2589° 411m)
Who: J-Dar
Herbarium specimen reported

Notes: White (when dry) foliose lichen primarily occurring on moss over sandstone, but occasionally occurs directly on the rock. Thallus turning greenish when wet, lobes darkened distally, with thick flaky pruina. Soralia marginal and laminal in older thallus material. Soredia appearing isidiate, or at least becoming large and globose in mature specimens. Lower cortex black, shiny, toward center, white and almost intermittent near lobe tips. Rhizines abundant, black, squarrose. Medulla pale yellow, K+Y, KC+Y (darker yellow).


Lobe tip upper cortex pruina
Thallus lobe tip underside with black cortex proximally and sqarrose rhizines
Laminal soralia
Medulla K+Y
Medulla KC+Y
Medulla pale yellow

Proposed Names

28% (1)
Recognized by sight
-76% (2)
Recognized by sight: Lower cortex partially absent at lobe tips.

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
I’m sorry, I scanned too quickly
By: Jason Hollinger (jason)
2015-10-14 16:59:52 CDT (-0400)

Didn’t notice that you’d already checked for weak cortex below tips. It is subtle, I agree.

Good Timing!
By: J-Dar
2015-10-14 16:53:33 CDT (-0400)

I just sat down to check the chemistry of this specimen, and there was Jason’s obviously correct comments. I was fooled by the seeming lack or intermittent cortex on the underside of the lobe tips, but there is cortex.
Chemistry notes: Medulla pale yellow, K+Y, KC+Y (a little darker). Soredia also K+ and KC+ similarly. These combinations put it right at P. enteroxantha.

I’d say these soredia are mostly marginal
By: Jason Hollinger (jason)
2015-10-14 15:03:01 CDT (-0400)

I would suspect P. enteroxantha, but P. leucoleiptes and P. isidiigera are also possibilities. It’s all about where the secalonic acid A is present if anywhere: throughout medulla, just associated with soredia, nowhere (respectively). I prefer to do KC test myself, I find the K and C (and some UV lights even work!) tests to be too ambiguous sometimes. KC is the most reliable for me.

An additionally useful character for verification is that P. perisidiosa usually lacks a cortex underneath near the lobe tips (a precursor to soralia formation I think).

Created: 2015-10-09 21:53:46 CDT (-0400)
Last modified: 2016-04-10 09:55:13 CDT (-0400)
Viewed: 51 times, last viewed: 2016-10-22 18:38:15 CDT (-0400)
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