Bonjour, j'ai trouvé cet asco sur le bouleau – c'est comme Diatrype disciformis.
This asco was on a birch twig, and looks like Diatrype disciformis from the microscopy. Spores were deposited as a pale brownish deposit, and were 6-8 x 1-1.5.
Asci were 8-spored, biseriate, tips blueing with Lugol (I think), 40-45 x 5 um.
Perithecia were multitudinous, without long necks.
Small ostioles dotted the stroma surface.
Ellis and Ellis state that this species is occasionally found on birch. I'm hesitant to call it Diatrype disciformis however, as the habit of growth is pulvinate and quite unlike D. disciformis as found on beech ie "erumpent through stellate fissures".
Steve