Observation 230762: Caloplaca Th. Fr.

When: 2016-01-28

Collection location: Monterey Co., California, USA [Click for map]

35.8129°N 120.2817°W 480m [Click for map]

Who: J-Dar

Specimen available

Habitat: Boulder field in semi-arid grassland habitat.

This is a tiny but distinctive Caloplaca with scant grey to rock-colored areolate thallus showing yellowing at spots of apothecia origin. Apothecia up to 1mm, concave, lecanorine, with a unique orange coloration (almost pinkish orange?). Margin thick and raised, without dark excipular ring, proper margin dominant and concolorous with disk or slightly lighter. Thalline margin present, but outside and beneath the proper margin, always with whitish-grey material on it that superficially resembles crusty pruina but I think is something else, maybe remnant thallus material? Spot tests: Thallus K-, C-; epihymenium K+R, C-; apothecial margin K+R, C- (Nash reports proper margin usually C+red-brown). Hymenium hyaline. Algal layer thick and continuous into thalline margin. Spores ellipsoid, slightly narrowed at septum at maturity. Width measurements taken at septum.
19.14×6.84µm (Q=2.8)
14.75×6.15µm (Q=2.4)
18.96×6.54µm (Q=2.9)
15.26×5.75µm (Q=2.65)
L’=17.02 W’=6.32µm. Q’=2.69


Proposed Names

-28% (1)
Used references: Every damn paper, key, book, photo I could find on Caloplaca
-28% (1)
Recognized by sight: Thallus should be closer to subsquamulose, which this specimen doesn’t appear to be.
57% (1)
Recognized by sight

Please login to propose your own names and vote on existing names.

= Observer’s choice
= Current consensus


Add Comment
Naw, that’s just photoshop magic
By: Jason Hollinger (jason)
2016-02-06 12:52:23 PST (-0800)

And a boring day with apparently nothing better to do! :)

By: J-Dar
2016-02-06 12:37:46 PST (-0800)

But the real question is, how did you get those spores to all line up like that (looked like one photo, not a compilation?)!

You’re problem here isn’t spore maturity
By: Jason Hollinger (jason)
2016-02-06 12:32:51 PST (-0800)

It’s an optical effect. The way to solve this problem is to “scorch” the slide briefly. (This is what Wetmore is talking about when he says “spores of fresh collections must be treated with heat for standard measurements of the isthmus”.) I use a bic lighter. Hold the slide a few cm above the flame, too close and it gets sooty, too far and it won’t heat properly. I count to five. But you’ll know you’ve gone too long when it starts to boil(!) If nothing happens at all, it’s too short. You’ll get good at it in no time. It’s not hard. And it makes a world of a difference. (See observation 230791 for an example showing side-by-side comparison of burnt and unburnt spores.)

Also note that this apparently works well in lots of genera where septation and wall thickenings are important characters, e.g., Rinodina! Other lichenologists are aghast when I mention it, but I’ve had extremely good luck with it.

The heating just helps equilibrate ion concentrations across membranes or something like that, helping ensure that the whole spore and surrounding mounting medium all share something like the same index of refraction. At least, this is how I understand it. Introducing K or Lugols, for example, will accomplish the same purpose. (Sheard recommends observing spores in Lugols for this very reason. But I find that the spores are hard to see in Lugols, so burning is afar better solution in my opinion.)

Ya not quite right, but…
By: J-Dar
2016-02-06 12:07:52 PST (-0800)

For septum width, when in spore development “should” it be measured? As you can see in the photos, it varies quite a bit with maturity.

I’m getting distracted by the orangish thallus, I think
By: Jason Hollinger (jason)
2016-02-06 11:45:28 PST (-0800)

But first: septum is lengthwise measurement of the thick septum in the middle not width at middle. Some authors measure it as a percentage of the total length of the spore. For example, in the spore in the upper left corner of the first spore photo I get 29% or 4 µm. By contrast, I calculate a width of 5 µm.

Normally this is not what is meant by thalline outer margin. It’s not normally “arachnoid” (tomentose) like this. It’s normally a well-delimited collar that looks exactly like the rest of the thallus, both color and texture.

Okay, let’s rule out C. luteominia. C. atroflava seems to be the best choice, as you say. Doesn’t feel right, still, but when does Caloplaca ever feel right?? :(

Spore measurements
By: J-Dar
2016-02-06 11:12:01 PST (-0800)

“45a Septum wide, > 4 μm”

Is the spore septum measurement the width of the spore at the septum or is the septum measured lengthwise along the spore?

The apothecia on this one are a little larger than reported for C. atroflava, but the white/grey material on the outer margin is distinct and constant across numerous different specimens, I just wasn’t sure if that was what is described as grey outer margin on that and C. sonorae. Also, the color is an off-orange that is not “normal” for what I have called C. luteominea. But, I also don’t see the black hypothallus described for atroflava.

Ah well, i’ll keep looking. I’m getting killed with saxicolous Caloplaca right now. Nothing in this region seems “typical” for the species I key them out as!

Haha! I feel the same way about Caloplaca frequently :)
By: Jason Hollinger (jason)
2016-02-06 10:07:41 PST (-0800)

I wouldn’t rule out C. luteominia completely yet. Those margins are so prominent. Spores are on the large side, for sure, but maybe overmature(?) The ones with well-developed septa are within range (septum included).

Created: 2016-02-06 08:32:42 PST (-0800)
Last modified: 2019-04-21 20:20:56 PDT (-0700)
Viewed: 78 times, last viewed: 2019-05-04 15:48:43 PDT (-0700)
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