Observation 280543: Trapelia M. Choisy

On weathered siliceous rock, north-facing.

Thalus white, thin, continuous, without prothallus, K-, C- KC-. Apothecia black. Hymenium hyaline, I+Blue ephemeral, epihymenium red-brown.

8 spores per ascus, uniserate. Asci cylindric, I+ pale blue, inner layer I+R? Spores simple, hyaline, broadly ellipsoid to tear-drop to egg shaped. About 18×11µm.


Polarized filter reactions
Heat treated, in KOH
K/I stain
K/I stain
Asci detail, K/I stain, after heat treatment.

Proposed Names

28% (1)
Recognized by sight
46% (2)
Recognized by sight

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Add Comment
Thanks for the paper Jason!
By: J-Dar
2017-07-02 02:05:18 CEST (+0200)

It seems this is a really distinctive genus, thank you both for the info. Like those ascus stains? I was really happy how they came out. Wish it was this easy for those species that require tholus characteristics! I had fun with the micro on this one as everything just behaved nicely.

Totally agree with zaca, too
By: Jason Hollinger (jason)
2017-07-02 01:57:21 CEST (+0200)

Interesting that you have trouble getting a C+r reaction. It’s usually quite strong in Trapelia. You might try doing a C test on an apothecial section for verification.

The excellent photos of ascus stains, and those peculiar pseudolecanorine apothecia clearly show Trapelia.

I wouldn’t worry too much about whether it is T. coarctata or T. glebulosa, those are definitely not good species (at least according to molecular studies). It’s just that no one really knows what the correct species concepts are…

100% Correct Zaca
By: J-Dar
2017-07-02 01:25:15 CEST (+0200)

Thanks for that, Trapelia is new to me but I tried and couldn’t get any C+ reaction on the thallus, so I figured even though it was biatorine that it might be some odd Lecanora. I can’t find a description of Trapelia glebulosa or a key to separate it from T. coarctata, but I’ll get it off Bio One at some point.

“A revision of the saxicolous, esorediate species of Ainoa and Trapelia (Baeomycetaceae and Trapeliaceae, lichenized Ascomycota) in North America, with the description of two new species”

Created: 2017-07-02 00:51:22 CEST (+0200)
Last modified: 2017-07-02 01:22:27 CEST (+0200)
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