Observation 197731: Rosellinia aquila (Fr.) Ces. & De Not.
When: 2015-02-01

Notes: Found at the annual BAMS “Mushroom Madness” walk with ranger Amy Wolitzer.

On thick bark of a deciduous tree, oak or maple (no conifers around).

Perithecia are completely dry inside, but there are spores within, 17-24 × 7-8. The spore size plus presence of small hyaline appendages at both spore ends should suffice to say R. aquila. [http://pyrenomycetes.free.fr/...]

Proposed Names

25% (1)
Used references: Petrini, L. E. (2013). Rosellinia-a world monograph. Bibliotheca Mycologica, 205.

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Eye3 = Observer’s choice
Eyes3 = Current consensus

Comments

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More ID work
By: Sava Krstic (sava)
2015-02-03 08:03:33 CET (+0100)

OK: no visible subiculum. I tried to revive one good-looking specimen, but it didn’t work quite well. The inside did revive in a way, it was easier to remove, but I was not able to see any ascii, or amyloid reaction anywhere. What I got looked pretty much the same as what I had yesterday.

I measured 21 spores and the results are, in your notation: (17-) 21 (-26) x (7-) 8 (-10).

Roo, thanks again for your help with this. If you can draw any conclusions, please do. Perhaps it should just be a Roselinia sp.

Re: ID work
By: Roo Vandegrift (Werdnus)
2015-02-03 06:33:51 CET (+0100)

I think in R. aquila, a defining trait is the persistence of the subiculum. Check out the other examples of R. aquila posted here, for example. Even when it’s dried out and starting to rot, it’s got that dark brown/black felty/wooly subiculum under the stromata.

Nice thing about fungi in the Xylariaceae like this one: they preserve almost perfectly by air-drying. Out here on the west coast, they tend to do that in the summer all by themselves, actually. If the perithecia appear dry inside from your fresh material, but you’re able to scrape out spores like the photo you uploaded, chances are it’s just dried out — try opening one up and putting a small drop of water inside, and then give it a few minutes to absorb. Eventually, the perithecial contents will re-hydrate and you’ll be able to scoop them out much more easily than scraping the inside of the dry perithecia.

Unfortunately, I probably don’t have time to take ownership of this one: I’m trying to defend my PhD next term! But, I can certainly help from here. I’d say the way to be sure of the identity is to check around for subiculum, get a good 10-20 spore average dimensions (lean to more, given the observed variation so far, I think), and get measurements of the stromata size: R. glabra is a little bit smaller than typical R. aquila. Also, if you have some, you could make the next slide in Melzer’s reagent, to observe the ascus apical plugs, which might help different the two species.

ID work
By: Sava Krstic (sava)
2015-02-03 06:11:39 CET (+0100)

Debbie and Roo: thanks!

Roo: Special thanks for the expert discussion. There is little of what one might call the subiculum here. I have no idea how much of the subiculum remains visible when there’s only carcass left of the fungus. The range I put is based on 4 measured spores. I’ll go back to this, but still have some fresh stuff in the fridge that I’d like to scope. Alternatively, you can become an owner of this collection and we would all learn about it much better.

applause!
By: Roo Vandegrift (Werdnus)
2015-02-02 19:19:14 CET (+0100)

I also applaud your follow-up, sir! But, something about this bugs me a little: there’s no evidence of the well-developed subiculum in your photo. The French pyrenomycetes site shows the typical R. aquila subiculum pretty well, and every time I’ve found this fungus in Oregon it’s pretty obvious.

Since you posted such great information about the spores, I ran your fungus through the keys in Liliane Petrini’s 2013 monograph of Rosellinia. It turns out, there is a very similar fungus called Rosellinia glabra (Fuckel) LE Petrini, which Fuckel considered a variety of R. aquila and Petrini split out into its own species in 1992. This fungus is nearly identical to R. aquila, but has a much reduced (and disappearing in age) subiculum, and slightly smaller spores. For R. glabra, the ascospore size range (with mean) given is (12.6-) 15.8 (-20.7) x (5.4-) 6.6 (-8.1), and for R. aquila (18-) 19.7 (-27) x (5.6-) 7.5 (-9.9). So your spores are a bit intermediate: might be worth measuring 10 or 20 to get an average and see which is closer, and re-examining the material for evidence of the subiculum.

If this is R. glabra, it’ll be the first North American collection — so far, it’s only known from Europe.

you, sir …
By: Debbie Viess (amanitarita)
2015-02-02 16:56:30 CET (+0100)

do some marvelous follow-up.

your field skills don’t suck, either. ;)

Created: 2015-02-02 08:36:57 CET (+0100)
Last modified: 2015-02-02 19:20:34 CET (+0100)
Viewed: 115 times, last viewed: 2016-10-26 17:45:11 CEST (+0200)
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