Observation 85615: Cetraria Ach.
When: 2011-12-29
Who: zaca
No herbarium specimen

Notes: Ironically, while studying the specimen considered in MO85608 to decide if it was or not a Cetraria, I found in a completely different habitat – sand dunes near the coast – what I think to be a species of this genus. It can also belong to some related genera. Unfortunately I have no reliable key to these kind of lichens. The species of Cetraria from which I saw photographs have, in general, pycnidia at the margin of lobes, which are more or less caniculate. In this specimen the lobes are more rotund and the pycnidia cover not only the margins but the whole lobes. Since there were a few of apothecia I made the microscopic observation and I join a set of pictures with it. The following approximate average dimensions were obtained for the spores:
Me = 6.9 × 4.1 µm ; Qe = 1.7 (N=30).
In face of Jason’s comment to Observation MO79464 I didn’t expect to
find any mention of Cetraria in the portuguese checklist; Since “noblesse oblige”… It’s hard to believe but there are 6 species of Cetraria there:
C. aculeata, C. commixta, C.islandica, C. merrilii, C. muricata, C. sepincola.
I had no access to the descriptions of species of this genus except for the one existing in CNALH.


Microscopy I – Apothecial sections.
Microscopy II – Details of apothecial sections: in congo red (top) and in Melzer (bottom).
Microscopy III – Asci and spores.

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It seems clear,
By: zaca
2012-01-04 14:44:27 CST (-0500)

but I meant in specimens like mine.

Not necessarily
By: Jason Hollinger (jason)
2012-01-03 20:29:19 CST (-0500)

This specimen is just bizarre. It’s so narrow-lobed I can’t even tell from the photos for sure whether it is even flattened or terete, let alone whether it has pseudocyphellae! Normal specimens of Cetraria are quite obvious. Here’s an example of C. islandica — couldn’t be more obvious, even to the naked eye!

image of C. islandica underside showing pseudocyphellae

I will take your …
By: zaca
2012-01-03 20:22:32 CST (-0500)

reccomendations in consideration for the future.
I find it very difficult to observe pseudocyphellae in specimens like this and even more to establish a pattern for their disposition.

So far as I can tell…
By: Jason Hollinger (jason)
2012-01-03 18:29:28 CST (-0500)

The cilia-like things are just called “marginal projections” in the literature. For example in one description of the genus (Brodo et al. 2001), the pycnidia are “black, buried in conspicuous marginal projections”. He never shies away from using the term “cilia” where more appropriate, so I must conclude that there is some esoteric reason for resisting calling these “marginal projections” cilia.

We have many species of Cetraria s. str. in N. Amer., but I can’t think any that look like yours! My best guess is that environmental factors are causing your specimen to look unusually narrow-lobed and bushy. The ones I’m familiar with (C. ericetorum, C. islandica, C. arenaria, C. laevigata) are all conspicuously broad-lobed in my experience. No help there!

Things to look for:

Position of pseudocyphellae on underside of branches: C. ericetorum has them in discontinuous lines along the underside of the margins; C. laevigata has them in continuous lines; C. islandica has them scattered in irregular shapes all over the underside; C. subalpina has none; and so on.

C and KC test on medulla: Cetrariella is C+ and KC+ pink or red from gyrophoric acid.

P test on medulla can also help: fumaroprotocetraric acid… which is also K+ brownish to reddish-brown depending on how strong it is.

I don’t know anything about the differences in spore size or shape, if indeed there are any.

Jason, some questions:
By: zaca
2012-01-03 18:14:51 CST (-0500)

- In your comment you wrote: “abundant cilia-like protrusions along the margins”. In my notes I call it “pycnidia”. What are these?
- Do you have some similar species in North America?

Now I understand better …
By: zaca
2012-01-03 18:08:27 CST (-0500)

the notes to the description of the genus in CNALH: "Thirteen segregates of Cetraria s. l. concerning the North American flora has been proposed: Allocetraria, Arctocetraria, Asahinea, Cetrariella, Cetrelia, Esslingeriana, Flavocetraria, Kaernefeltia, Masonhalea, Platismatia, Tuckermannopsis, Tuckneraria and Vulpicida (Randlane et al. 1997). According to your comment some more should be added. Before posting this observation I gave a look to some species of the genera mentioned above and the features were a bit different from those of Cetraria s. str. Thanks, Jason, for clarifying the subject.

Cetraria sensu lato
By: Jason Hollinger (jason)
2012-01-03 14:17:43 CST (-0500)

Part of the problem you’re having here is that the genus Cetraria is a mess. Only one of these species is Cetraria sensu stricto: C. islandica. You might have more luck finding descriptions under these names:

aculeata & muricata – Coelocaulon aculeata & C. muricata

Both are small, dark brown, shiny fruticose species with terete branches.

commixta – Melanelia commixta and/or Cetrariella commixta

This is a foliose species, also dark brown and shiny, growing on rocks.

merrillii – Kaernefeltia merrillii

This is a small, black, dull, broad-lobed fruticose species, growing on conifers.

sepincola – Tuckermannopsis sepincola

This is a tiny, brown, shiny foliose species which grows on the base and twigs of a relatively small number of species of live shrubs, including (in North America) Shepherdia and Alnus.

Definitely none of these match your observation. However, Cetraria islandica is a much broader-lobed species than yours, as well. Where does that leave us?? From what I can see, I agree with you that this is Cetraria s. str. — dark brown, fruticose, growing on ground, flattened, channeled branches, abundant cilia-like protrusions along the margins, apothecia are right. I don’t see how to avoid concluding that you have yet another species not reported for Portugal! :)

Created: 2012-01-03 13:41:29 CST (-0500)
Last modified: 2012-01-03 13:58:58 CST (-0500)
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