When: 2017-02-23

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

35.659°N 120.1739°W 692m [Click for map]

Who: J-Dar

Specimen available
Collection number: Jason Dart 750

On old weathered redwood fence post, along Annette Road just east of the SLO County line into Kern.

Thallus dark brown, with overlapping lobulate shiny areoles, cortex C-. Apothecia one (several) per areole, deeply immersed, slight parathecial ring and elevated crown visible in many. Disk dark brown, reddish when wet, roughened. Hymenium 125µm tall.

Spores about 4×2µm


100x in water
Hymenium 125µm tall, as measured here
Thallus cortex x-section

Proposed Names

57% (1)
Based on microscopic features: Hymenium height
Based on chemical features: C-

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= Observer’s choice
= Current consensus


Add Comment
Not sure what the correct way to do all these measurements
By: Jason Hollinger (jason)
2018-01-12 13:13:34 AEST (+1000)

I personally include the epihymenium in the hymenium depth, so I would have called your hymenium 150um not 125um. (I do fully agree with where you’re starting the measurement on the bottom though: more or less where the asci start to grow… which means that the asci should be almost by definition almost as long as the hymenium is high! Although note that asci don’t always reach all the way to the top of the hymenium.) And that is totally fine for americana. The main thing is that it’s > 100µm (to distinguish it from veronensis).

For cortex, Kerry is pretty careful to include all of the above: the total thickness of the live hyphae (what I consider the cortex thickness: everything between the epinecral layer if present to where the algae start, and note that the lower limit can be irregular and indistinct), as well as breaking that layer up into the colored upper part and the uncolored lower part, and of course the amorphous hyaline epinecral layer on top of the colored upper cortex. I think Kerry calls the epinecral layer the “syncortex” and the living part (both uncolored lower part and colored upper part) the “eucortex”.

Hymenium height & cortex thickness
By: J-Dar
2018-01-12 12:44:31 AEST (+1000)

I put the measurement bar at 125µm in the photo because I wasn’t sure I was measuring it entirely correctly. 125µm shouldn’t be too tall for americana?

Cortex thickness: What are you measuring exactly? The dark red layer is about 15µm, and about 40µm total including the medulla. I assumed the published thickness only included the colored outer layer?

And yes, the crown isn’t showing in this section. I really should focus on that in my next sections.

Tried hard to find another name for this
By: Jason Hollinger (jason)
2018-01-12 06:13:46 AEST (+1000)

But couldn’t. The combination of unusually tall hymenium, no epinecral layer, narrow elongate spores rule out all my other candidates, even unnamed things.

I’m assuming the reason it looks “wrong” to me is just that it’s growing on a silly twig!

I measure about 30-40µm cortex off of your photo, by the way. In fact, the only micro character off at all is that the gorgeous apothecium section in your photo doesn’t actually show the parathecial crown, but that’s not at all unusual. Not every apothecium shows it well. (Note that the brown from the upper edge of the cortex extends almost all the way to the hymenium.)