Bonjour !

Voici un Lachnellula willbommii probable.

La pousse sur mélèze et les grandes spores sont conformes.

Merci de nous aider !

Roland

Données : 

Date de récolte : 22 / 06 / 2013

Substrat : branche morte de mélèse

Asques non operculés, à 8 spores unisériées, avec  crochets à la base et pore apical fortement amyloïde avec prétraitement dans le KOH puis dans le Melzer, à contenu légèrement dextrinoïde vers l'apex, 110-127 x 9-12 µm

Paraphyses étroitement cylindriques, parfois légèrement plus larges vers l'apex et avec un septum vers la base, non ramifiées, à contenu lipidique  et fines guttules jaunes réfringen-tes jusqu'à  80% et plus, 113-170 x 2,5-4 µm, dépassant les asques d'environ 5-15 µm

Spores moyennement à étroitement ellipsoïdes, rarement subfusoïdes, lisses, à paroi légèrement épaissie, avec 1-2  guttules, 12-20,5 x 5,5-7,5 µm, 15,7 x 6,4 µm en moyenne, Q = 2,45

Sous-hyménium formé de petites hyphes emmêlées, sinueuses, septées, 1,5-2 µm de diam.

Excipulum en textura prismatica ascendant, gélatinisé, formé d'hyphes septées, à paroi épaissie, 2-3 µm de diam.

Revêtement externe formé de cellules globuleuses à ellipsoïdes, à paroi épaissie jusqu'à 1 µm de largeur, 7-10 x 6-9 µm

Medulla ± en textura intricata, à pigment jaunâtre ± gélatinisé, difficile à préciser

Poils marginaux cylindriques, arrondis à l'apex, septés, finement incrustés, hyalins, jusqu'à 150 x 2,2-4 µm

Hans-Otto Baral, 18-03-2014 11:47

Re : Lachnellula willkommii ? - 50568

Hi Roland

I would say L. occidentalis, but the delimitation to L. willkommii is rather obscure. The latter is a more obvious parasite, but who knows...

Could you please test with Lugol? The apical ring looks inamyloid but I suspect you get a red reaction of the wall in Lugol. And after short influence of KOH you will get a blue ring (I suppose). The species can also be inamyloid, but then the apical wall is thinner.

Zotto

David Malloch, 18-03-2014 14:48

Re : Lachnellula willkommii ? - 50568

Hi Roland,

Lachnellula willkommii is found in New Brunswick, Nova Scotia and PEI, but as far as I know, is not reported from Québec.  If it is there, it would be a serious concern to the forest industry and should be reported to federal or provincial forestry officials.

Where I live, near Saint john, New Brunswick, the fungus is very common and infects many or maybe all larches (Larix laricina).  If you have that species you should be able to find swollen cankers on the branches, especially of young trees.  The apothecia on the cankers are often accompanied by shiny layers of resin.  The pictures are of this species as I find it near my home.

Dave

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Hans-Otto Baral, 18-03-2014 18:35

Re : Lachnellula willkommii ? - 50568

Hi Dave

Didi you never see a red reactive apical ring in all these samples? Is there no occidentalis in your area?

See also our previous discussion 
http://www.ascofrance.fr/search_forum/21908

There you gave the same ascus photo. Are these canker photos here also from the same specimen (Feb. 2013)?

In the meantime further sequences have been deposited in GenBank.
I made a phylotree and again recognize the confusion around this complex.

Note that the very same CBS strain of occidentalis appears at two different positions (lilac), sequenced by Verkley and by Hamelin.

Zotto

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David Malloch, 18-03-2014 19:44

Re : Lachnellula willkommii ? - 50568

Hi Zotto,

The picture of asci was from twigs that had fallen from a tree during a winter storm.  The cankers were photographed in April of the same year on different trees, so it is possible these are not both L. willkommii.  I could test the material in KOH+Lugol now, but they may be too old.  Perhaps I should collect some fresh material and try again.  I believe both would be easy to find.  If I find them, would someone like to sequence these?  If so, cultures or apothecia?

Regards,

Dave

Hans-Otto Baral, 18-03-2014 20:27

Re : Lachnellula willkommii ? - 50568

Roland: is it possible that your Lugol is too thin? Another possibility is that the remaining KOH reacts with iodine by discoloring it. This happens when not washing with water beforehand. The cell plasma mit take up the yellowish-brownish iodne stain, then you can be sure.

But Lugol directly without KOH should give a red reaction then. 


Dave: The material can hardly be too old to test the iodine reaction. Only after 30-50 years this may happen that a red reaction changes to blue. So when you add Lugol directly you can see. But your ascus tips look too thin-walled to contain such an amyloid ring.

Pedro Crous from CBS, Netherlands, is interested in culturing and sequencing Helotiales, especially pathogens. Sending of air-dried apothecia should enable him to have active asci still. I can ask him.

Zotto

P.S. Just got his answer:
"Dave can send me the material or give it to Keith Seifert to bring in April, but I receive packages in good order from Canada - if it's a pathogen, I am hooked!"

David Malloch, 19-03-2014 14:43

Re : Lachnellula willkommii ? - 50568

Thanks Zotto.  I'll write to Pedro and find out the best way to proceed.

Dave