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Hi, I've found this ascomycete on a dead lying s

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Discomycète sur écorce
Pascal RIBOLLET, 05-09-2017 09:31
Bonjour Forum,
Trouvé sur écorce de feuillu, il émergeait d'un Tomentella sp (mais pas greffé dessus).
Coupe jusqu'à 1 mm de diamètre, longuement stipitée (jusqu'à 3mm). Spores brunes déjà dans l'asque, 3,5-4,5 (5) x 2-2,5 µm, lisses (immersion), deux guttules discrètes. Asques 35 x 5 µm, à 8 spores unisériées, MLZ-
Pas observé de paraphyses.
Poils marginaux jusqu'à 50 x 2,5-3,5 µm, à paroi épaisse de 0,5 µm, hyalins, non septés.
Excipulum en textura globosa-angularis hyaline de 12-25 x 8-15 µm, cellules de taille assez variable.
La zone du haut du stipe/base de la coupe présente une texture prismatica d'hyphes hyalins de 5 µm de diamètre.
Un Discomycète à l'hyménium surprenant par rapport au reste...J'ai d'abord cru qu'il était parasité.
Qu'en pensez-vous ? Merci pour vos avis
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  • message #50268
  • message #50268
  • message #50268
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Hans-Otto Baral, 05-09-2017 09:59
Hans-Otto Baral
Re : Discomycète sur écorce
Hi Pascal

Very interesting! Did you test the asci also with Lugol? 

Perhaps a Lambertella but the spores are very small. 

I assume your microscope light is too weak and also would need more blue light (blue filter). Did you ever try a strong LED below the condensor?

Pascal RIBOLLET, 05-09-2017 12:33
Re : Discomycète sur écorce
Lambertella ! That seem to fit very well. I did not know the genus (only "on the books"). The synoptic key by Korf & Zhuang lead to only four species with such small spores. Within those species, Lambertella microspora (Seaver) Dumont seems to be a good lead, but I must check.

I could not test with IKI because I must renew it...

You're right for my microscope : my 30W broke and I've only found a 20W. I've to change it and also rectify the light's tone...

Many thanks Zotto !
Hans-Otto Baral, 06-09-2017 10:29
Hans-Otto Baral
Re : Discomycète sur écorce
Looking at the synoptic key I see that Lambertella microspora has an ascus pore turning blue in iodine. As you do not have Lugol, I suggest to do KOH-pretreatment: Put a small part of hymenium in a drop of ca. 2-5% KOH and wait a few seconds, then try to dilute the KOH with water. Remove also the water and add enough MLZ so that the preparation remains redd-brown. Add the cover glass and look for the ascus tip. (sorry when you know the procedure)

three other species would have inamyloid asci: 1, 27, 44 (acuminata, minutula, zeylanica), but all of them are simultaneoiusly listed in the J+ lead. But spore shape does not seem to fit to either species (laterally flattened, one end broader), except for microspora. zeylanica is also excluded by spores hyaline in the asci.

Pascal RIBOLLET, 08-09-2017 12:40
Re : Discomycète sur écorce
Hi Zotto,
I've done the KOH-pretreatment : no reaction at all.
In the synoptic key, tree of the four species selected on spore-size (acuminata, minutula, zeylanica) can either turn blue or not. Only microspora must turn blue.
So not microspora.
But as you wrote,  zeylanica is excluded by spores hyaline in the asci and spore shape does not fit to acuminata and minutula.
I fear we can't go further than "Lambertella sp." ?

Thanks for your help !

Hans-Otto Baral, 08-09-2017 12:44
Hans-Otto Baral
Re : Discomycète sur écorce
Yes, I do not so any solution. In the worst case your fungus is not sclerotiniaceous at all. I suspect this a bit because the excipulum is hyaline without any incrustation. Lambertella is heterogeneous and includes also Helotiaceae and other families.