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04-11-2025 12:43

Edvin Johannesen Edvin Johannesen

Hi! One more found on old Populus tremula log in O

04-11-2025 09:07

Josep Torres Josep Torres

Hello.A suspected Hymenoscyphus sprouting on a thi

04-11-2025 14:53

Josep Torres Josep Torres

Hello.Very small, globose, mucronate perithecia, b

03-11-2025 21:34

Edvin Johannesen Edvin Johannesen

These tiny (0.4-0.5 mm diam.), whitish, short-stip

03-11-2025 19:41

David Chapados David Chapados

Hi,Does anyone knows which genus could this be? G

28-10-2025 15:37

Carl Farmer

I'd be grateful for any suggestions for this strik

03-11-2025 16:30

Hans-Otto Baral Hans-Otto Baral

Hello I want to ask you if you have found this ye

01-11-2025 09:14

Francis Maggi

Bonjour,Trouvé sur Xanthoria parietina à Valdebl

28-10-2025 19:33

Nicolas Suberbielle Nicolas Suberbielle

Bonjour à tous,Je voudrais votre avis sur cette r

31-10-2025 09:19

Lothar Krieglsteiner Lothar Krieglsteiner

Can somebody provide me with a file of:Rogerson CT

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Black pulvinate asco on Prunus
Ethan Crenson, 26-08-2017 15:56
In the Green Mountains of Southern Vermont, US.  Black pulvinate fruiting bodies 1-3 mm by 1-2mm, sometimes converging into larger forms.  They don't appear peritheciate.  Asci are 102-141 by 12.5-15µm, IKI-.  Paraphyses (not adequately illustrated with my photos) are filiform, some tapering at the ends.  Spores ellipsoid to inequilateral ellipsoid, hyaline with oil droplets, 15.5-18.5 (22) by 5-7µm.  In cotton blue some appear 2-septate.  In KOH they exude deep red pigments.  Thanks in advance for your input.
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Hans-Otto Baral, 26-08-2017 16:08
Hans-Otto Baral
Re : Black pulvinate asco on Prunus
Hi Ethan
Remarkable fungus! I am not sure if the asci stand in a hymenium at the surface of these ascomata or if they are in cavities, i.e., perithecia in a stroma. Do you have survey photos of a section that perhaps show such cavities?

The ionomidotic KOh reaction reminds of a Codieritidaceae

Zotto
Ethan Crenson, 26-08-2017 22:10
Re : Black pulvinate asco on Prunus
Zotto,

In the fourth photo I tried to show a cross section of two ascomata.  As you can see there is a distinct dark layer at the surface and light brown tissue in the interior.  However, I don't detect perethecia in the black layer.  I am including a closer version of one of the section photos here. 

I can't find Codieritidaceae in Google. If there's a typo, I'm afraid I can't figure it out. 

Ethan
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Hans-Otto Baral, 26-08-2017 22:18
Hans-Otto Baral
Re : Black pulvinate asco on Prunus
Sorry, it is Cordieritidaceae. It is a vast group of encoelioid discomycetes.
I would prefer doing a thin section for transmitted light, and also to show the paraphyses.

It may be important too to look whether the ascus tip gets thick-walled in the dead state (after shortly heating the slide or adding MLZ or KOH).
Ethan Crenson, 26-08-2017 22:27
Re : Black pulvinate asco on Prunus
Perhaps these are a little clearer.  I am prepareing to do a thin section as you suggested.
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Hans-Otto Baral, 27-08-2017 07:20
Hans-Otto Baral
Re : Black pulvinate asco on Prunus
Yes, it looks like a hymenium covering the whole exterior. I see dark olive dots on the hymenial surface which probably represent exudate on the paraphysis tips, could you supply  a photo with oil immersion showing thse tips? I assume in KOH this exudate gets dissolved as well?

What also shows the ionomidotic reaction is the genus Dermea. This should contain crystals in the medulla and angular cells in the ectal excipulum.
Ethan Crenson, 29-08-2017 06:51
Re : Black pulvinate asco on Prunus
Otto,
Yes, the exudate on the paraphysis tips dissolves in KOH.  In the photos provided here you can see the paraphyses, both covered in the exudate and naked.  I've also tried to find the features of asci in the dead state and the exipulum that you mentioned, but I'm not sure if I succeeded.
Thank you for your help,
Ethan
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Hans-Otto Baral, 29-08-2017 07:34
Hans-Otto Baral
Re : Black pulvinate asco on Prunus
Yes, this looks good enough to make up one's mind. The apical thickening of the asci is clearly visible, also I think I see many crystals in the excipulum. The latter would clearly exclude a Cordieritidaceae and support that this is a Dermea.

When I go with Groves' (1946) key in Mycologia 38: 364, then I arrive at the common Dermea cerasi.  Ascus and spore size fits well (dead asci in KOH are certainly smaller than the living ones you have measured). Only the anamorph is missing, but anyway I am sure.

Zotto