Observation 93004: Tephromela atra (Hudson) Hafellner
When: 2011-04-06
Who: zaca
No herbarium specimen

Notes: Growing on siliceous rock.

Proposed Names

61% (2)
Eye3 Eyes3
Based on microscopic features
Based on chemical features: C-, K+ yellow, KC+ yellow.

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Eye3 = Observer’s choice
Eyes3 = Current consensus


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Yes, I begin to understand …
By: zaca
2012-06-27 18:29:44 CDT (-0400)

that this is not a two game play, because that there other species beyond Lecanora gangaleoides and Tephromela atra, like L. argentea, for instance, and possibly some others.
Concerning Tephromela atra, I’m not so sure about the consistency of the vinaceous colored epihymenium to make it a distinguish feature, i.e. it is of great help, if present, but it can be absent or indiscernible if too dark. This is just a thought with no scientific basis.
Your not yet posted specimens are very nice and the apothecial section spectacular. Thanks for sharing these. For instance, the red/orange reaction of the hypothecium was a surprise for me; I already saw it mentioned for other species of Tephromela, but not for T. atra. And if the apothecial section was not so thin one could miss the vinaceous color when observed just in water.

I’m not so sure about this
By: Jason Hollinger (jason)
2012-06-27 14:54:29 CDT (-0400)

I’m trying to make sense of what I’m reading in various floras (North American, British, Sonoran), as compared to my notes and other observations. According to the literature, you’re right, the hymenium can be hyaline below, but all my experience shows that the hymenium is entirely colored, especially when you introduce KOH/NaOH. See the micrographs in observation 68668 and observation 94162. But also see these photos from southern California (not posted yet):

specimen 1
specimen 2
specimen 1
specimen 1

This was a particularly thin section, so the vinaceous coloration is faint and all but missing from the lower parts of the hymenium and subhyenium; but note that strong, distinctive K reaction as usual, though. (I was personally present when K. Knudsen verified the specimen for me. It had a strong C/KC+ red-orange reaction, making me think it was something odd.)

Anyway, the point I’m trying to get to here is that I don’t see any convincing vinaceous color in the hymenium, and no K reaction at all. The strong blue reaction in Melzer’s is not indicative: according to the Sonoran Flora (and my own experience) Lecanora has a strongly amyloid hymenium.

[The technical characters separating Tephromela from Lecanora and Lecidea are obscure — Bacidia-type asci, poorly-developed proper exciple, etc. Good grief. Fortunately the common one, T. atra has this striking vinaceous, K+ coloration.]

Created: 2012-04-19 19:15:26 CDT (-0400)
Last modified: 2012-04-20 03:06:49 CDT (-0400)
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