Observation 90978: Pyrenula occidentalis (R.C. Harris) R.C. Harris
When: 2012-03-10
Who: zaca
No herbarium specimen

Notes: Average dimensions of the spores: Me = 23.4 × 10.2 µm ; Qe = 2.3 (N=20).

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Eye3 = Observer’s choice
Eyes3 = Current consensus

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The sample …
By: zaca
2012-03-27 14:21:04 EDT (-0400)

was too small and I spent it all on the preparations made​​. So I can not do more tests. It seems to me that the perithecia are too small (cf. MO76247 and MO72698 where the same scale was used) and the spores are too short for P. macrospora.

Orange pigment inside hymenium
By: Jason Hollinger (jason)
2012-03-27 13:57:08 EDT (-0400)

Could make this P. nitida instead of P. occidentalis… but I see the range is incorrect (avoids oceanic areas). As I’m sure you already know, your spore size matches P. occidentalis, being slightly too wide for P. nitida and P. laevigata. The only other one that seems promising is P. macrospora, which has spores > 27µm long. That exhausts the British Flora.

Two points to help confirm: P. occidentalis has an orange pigment (K+ deep wine red) scattered on outer surface, especially of the perithecia, spot test apparently visible in cross-section. Also the hymenium is is strongly inspersed with tiny oil drops making it appear cloudy.

I uploaded already …
By: zaca
2012-03-27 05:34:39 EDT (-0400)

a bad photo of the microscopy. The spores are similar to those of the others species that I have encountered, though shorter. For the other one (P. laevigata?) I was not able to see the spores.

Both these two species (occidentalis and laevigata) are in the British Flora
By: Jason Hollinger (jason)
2012-03-26 19:00:53 EDT (-0400)

But there are a number of additional observations that would help verify your id: are the spores colorless or dark?; muriform or with just a few septae?; exciple dark all the way around or more strongly pigmented on the sides and poorly pigmented below?; is anything in the hymenium or exciple K+ purple-red under the microscope?

You probably have the answer to a number of these already.

Created: 2012-03-26 18:41:38 EDT (-0400)
Last modified: 2012-03-26 18:41:41 EDT (-0400)
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