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Add-on topic http://www.ascofrance.com/forum/7059
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Rhizodiscina lignyota?
Edvin Johannesen,
15-02-2019 20:44
Hi!
These black, semi-immersed/erumpent apothecioid ascomata on Salix (?) twig, have spores which strongly resemble Rhizodiscina lignyota. But the spores are too large; 20-25 x 7-9 microns. Are we in Patellariaceae or am I totally lost?
Hans-Otto Baral,
15-02-2019 21:12
Re : Rhizodiscina lignyota?
the asci are also too slender for Rhizodiscina. Did you test IKI?
How look the paraphyses? The dead asci are very thick-walled as I see, surely they are fissitunicate.
Are the asci in perithecia, did you do a vertical section for a macrophoto?
How look the paraphyses? The dead asci are very thick-walled as I see, surely they are fissitunicate.
Are the asci in perithecia, did you do a vertical section for a macrophoto?
Edvin Johannesen,
15-02-2019 21:39
Re : Rhizodiscina lignyota?
The second photo is a cross section. I see no perithecia or ostioles. I will check IKI and paraphyses. Thanks so far!
Edvin Johannesen,
15-02-2019 22:45
Re : Rhizodiscina lignyota?
The spores turn bluish green in Lugol, but I do not see any IKI+ in the asci. I am unable to see paraphyses (Congo Red). There are indeed som pale loci within the stromata, so the hymenium seems to be localised to those. But I see no opening to the outside.
Edvin Johannesen,
15-02-2019 22:45
Re : Rhizodiscina lignyota?
Congo Red.
Gernot Friebes,
16-02-2019 07:42
Re : Rhizodiscina lignyota?
Hi, Edvin,
I think you might have Dothidea sambuci there.
Best wishes,
Gernot
I think you might have Dothidea sambuci there.
Best wishes,
Gernot
Hans-Otto Baral,
16-02-2019 08:32
Re : Rhizodiscina lignyota?
Indeed, Gernot, it is. The species doe snot seem to be very host specicif, as I have here also a sample on Berberis? Sambucus would easily be recognised by its large pith, did you check that, Edvin?
Edvin Johannesen,
16-02-2019 11:35
Re : Rhizodiscina lignyota?
Indeed! There are 16 previous collections from Norway, of which seven have substrate information; six on S. nigra and one on S. racemosa. Looking at it now (should have seen it right away), this one is undoubtedly Sambucus racemosa.
Thanks a lot for your help.
Edvin