When: 2017-04-20

Collection location: Cambria, California, USA [Click for map]

35.5184°N 121.0557°W 137m [Click for map]

Who: J-Dar

Specimen available

On sandstone in full sun. Coastal grassland.


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I admit this would be an unusually crustose form
By: Jason Hollinger (jason)
2017-06-17 07:10:39 PDT (-0700)

But when I look at all of my personal observations I see a very pronounced variation from extremely bullate-squamulose to appressed-squamulose. Yours is only a slight extrapolation from the latter form. I do have notes of several specimens directly on exposed rocks — looking more obviously squamulose, but nevertheless on bare rock in direct sun.

re: T. wallrothii — Presuming you have read the comments under T. glaucopholis in the Sonoran Flora, you know just as much as I do! I guess that is considered the “final word” on the subject.

By: J-Dar
2017-06-17 07:02:20 PDT (-0700)

I was looking at this family last night too, because of the chemistry that matches, and other features. Trapeliopsis glaucopholis is a good fit, except that this one is on rock and it typically occurs on soil. My previous experiences with the species (observation 270451 and observation 236902) are from mossy shaded areas, where this one is in full sun. But I had a note on one that the C reaction was fleeting, as was this with KC. The yellowish hymenium is also distinctive, and a good match.

And yes, I didn’t mean thalline margin, just a raised margin.

What’s up with Trapeliopsis wallrothii? Is that name now limited to European material?

Okay, throw out Lecidea, too
By: Jason Hollinger (jason)
2017-06-17 05:56:18 PDT (-0700)

How about Trapeliopsis glaucopholis or kin? Spore size, epihymenium/hymenium/hypothecium color, chemistry all correct.

Just realized you said this has a prominent thalline margin. Typo? That looks more like a black lecideine margin with faint pruina especially on the outer edge. But presence of algae in a spongy medulla-like layer in the cross-section would certainly prove me wrong. But if it truly is lecanorine, then I haven’t a clue what this could be!

I agree
By: J-Dar
2017-06-16 19:23:43 PDT (-0700)

but I couldn’t get there! So Lecidea without the green epihymenium? Let me run that thought down and i’ll report back, thanks!

This looks more like a Lecidea to me
By: Jason Hollinger (jason)
2017-06-16 16:58:48 PDT (-0700)

The spores are too small, and the hypothecium too dark to be any of the species of Lecidella I’m familiar with. Way too small for L. stigmatea. L. carpathica has a dark hypothecium, too, but I would describe it as “bright orange- or red-brown”, and it becomes even brighter in K. Yours just looks dark blackish brownish, typical of Lecidea.

There is a form of Lecidea fuscoatra which is whitish; would that work? (I think it might have a name at species rank, L. grisea?) A good way to verify weak gyrophoric acid is to apply C under the coverslip of a thin section. Preferably a section with both cortex and exciple, because there are a few Lecidea with weak gyrophoric, sometimes only visible fleeting under the microscope in the exciple. (And since the exciple is black, it’s a hard one to see!)

Additional info
By: J-Dar
2017-06-16 15:20:02 PDT (-0700)

This is a large distinctive crustose lichen on rock. The thallus is white, areolate, becoming subsquamuluse on the margins. Spot tests should be done again because of the odd results of K-,C-, KC+R (fleeting but distinct). All spot tests done under dissecting scope at 8-16×. Apothecia are common, rather large, black, plane, with a prominent thalline margin, epruinose. Pycnidia are common, showing as tiny black ostioles. Conidia not examined. Hymenium is dingy yellowish, hopothecium dark, and the epihymenium is reddish-brown.

Spores 8/ascus, simple, hyaline, broadly ellipsoid. 6.7×4.5, 7.6×3.6, 7.3×4.1, 6.8×4.6, 10.0×5.0.

Analysis: I struggled with this one because the spore measurements are significantly smaller than the literature states, and the chemistry was different than expected for Lecidella. However, as seen in the apothecia cross-section, I did not get a look at any asci or mature spores, so measurements were from a couple of spores that squeezed out and are likely small. I don’t know what to say about the chemistry. The K and C negative reaction seemed good at the time, and the KC+R was a cool fleeting color flash then it vanished. I’m not sure what acid creates the KC+R reaction here, it seems it is not gyrophoric acid.

Created: 2017-04-30 07:11:48 PDT (-0700)
Last modified: 2017-06-17 07:00:48 PDT (-0700)
Viewed: 75 times, last viewed: 2019-08-12 08:32:37 PDT (-0700)
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