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26-08-2017 15:56

Ethan Crenson

In the Green Mountains of Southern Vermont, US. 

26-08-2017 20:29

Guy Lambert

Bonjour à tous, Asco avec poils ; 2 à 3 mm maxi

28-08-2017 19:12

Ethan Crenson

Hello, I'm not sure what's going on here.  I foun

28-08-2017 10:57

Thomas Læssøe

Stipe long and black and par of the cup likewise g

26-08-2017 17:36

Bernard CLESSE Bernard CLESSE

Bonjour à tous,Voici un asco rouge trouvé sur or

26-08-2017 19:32

Chris Yeates Chris Yeates

Bonsoir tousdoes anyone have a pdf of Petrini et a

27-08-2017 11:09

Rubén Martínez-Gil Rubén Martínez-Gil

Hola a todos. Estamos sufriendo una gran sequía

27-08-2017 19:10

Andgelo Mombert Andgelo Mombert

Bonsoir à tous,Sur bois mort de feuillu au fond d

26-08-2017 23:45

Andgelo Mombert Andgelo Mombert

Bonsoir à tous,De jolies Trichophaea sur terre nu

26-08-2017 23:36

Andgelo Mombert Andgelo Mombert

Bonsoir à tous,Des jolies scut' poussant sur bois

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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