Observation 362458: Pertusaria DC.

When: 2019-03-30

Collection location: Stockbridge, Henry Co., Georgia, USA [Click for map]

Who: Chris Cassidy (cmcassidy)

No specimen available

On hardwood, thallus very greenish/yellow, with fruiting warts exhibiting a yellowish ostiole at the peak. Cortex C+deep yellow to orangish-red, K- to slowly y, KC-. Ostioles also Cr, KC+reddish. Spores with several small oil drops; ~35-70 × 18-40 μm. Asci becoming very greenish-blue in Melzer’s.


Spores – 1000x in Melzer’s

Proposed Names

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Add Comment
Nice view of proposed technique,
By: zaca
2019-04-02 04:51:21 PDT (-0700)

Thanks J-Dar.

Slice, slice, and slice again!
By: J-Dar
2019-04-01 19:30:41 PDT (-0700)

That’s my only advise and best trick. But I like the idea of cutting the section in half, like opening a zip-loc baggie and pouring out the asci…

Thank you zaca!
By: Jason Hollinger (jason)
2019-04-01 08:18:02 PDT (-0700)

re: cutting section in half — I never thought to try that.

(And yes, Chris, I, too, have trouble judging pressure with pencil eraser. I used to use forceps tips, but I’ll be damned, the pencil eraser really does work better!)

The advices of jason …
By: zaca
2019-04-01 08:12:05 PDT (-0700)

are all good, but I will add something: if you are not trying to make a clean apothecial section, then after making an apothecial section with the rasor blade, cut it by half. This will provide a zone in hymenium from where the asci and spores will enter the mounting media while pressing the coverslit.
From “a King without Kingdom”!

That’s funny
By: Chris Cassidy (cmcassidy)
2019-04-01 08:07:35 PDT (-0700)

I actually was reading a discussion between Zaca and yourself on slide/mount preparation and saw the pencil eraser tip that Zaca mentioned. I did try that, but to no avail, may have been pressing too hard (tough to gauge what is too hard unless you know, I guess). I’m looking forward to what these gentleman can add! Thanks

Counting spores in Pertusaria
By: Jason Hollinger (jason)
2019-04-01 07:25:51 PDT (-0700)

Is difficult in the best of circumstances. Those enormous asci love to rupture no matter how you do the section. Maybe zaca — the King of microscopy and much else besides :) — has some clever advice on separating Pertusaria asci without damaging them. Maybe some combination of mounting in KOH and very gentle pressure on the coverslip with a pencil eraser? Also wetting the fruiting wart before sectioning it may help? J-Dar, what’s your experience?

Thanks Jason,
By: Chris Cassidy (cmcassidy)
2019-04-01 05:25:34 PDT (-0700)

You’re correct. I keyed out P. texana and P. xanthodes, and read that they exhibit same chemical reactions, but the latter has only two spores per ascus. Unfortunately, my lack of a dissecting scope prevented me from getting a nice, clean section. All of the asci that I found weren’t in tact, so I couldn’t really determine whether or not there were two or more spores in them. I still have the sample, so I’m hoping to get another chance to try to scope this one a little better. Thanks again for all of your insight.

You probably already saw
By: Jason Hollinger (jason)
2019-03-31 21:36:38 PDT (-0700)

But there are three possibilities here, I think: P. texana, P. epixantha, and P. xanthodes.

P. texana supposedly often has raised ostioles, and is K+y P+o.
P. epixantha supposedly often has depressed ostioles, and is K~ P-.
P. xanthodes has only two spores per ascus instead of 8.