Attached are some pictures of a pyrenomycete grown on a moist lying, unbarked hardwood branch.
The perithecia grow singly, sunken, 150-300µm below the black discolored wood surface and the ostioles protrude only slightly above the surface. Apically, the ostioles are divided with 2-4 furrows. Perithecia measure 400-500 x 300-400µm (LxW).
Asci clubbed-cylindrical, 8-spored, monoserate; 152.5x10.3; 126.36x10.1
Apical ring congophyllous 2.7x1.5; 2.7x1.2 KR; 2.9x1.5µm
Spores elliptic, hyaline, with numerous LB's and indicated one large oil droplet
10.6-15.3 x 4.7-6.4µm; MW(10): 12.5 x 5.7µm; Q = 2.2

While researching, I came across Lentomitella based on the spore shape and apical ring, their spores are supposed to have longitudinal grooves, but I can't see them. Also, the ascus length and spore dimensions don't really fit the data I found.
Does anyone have any idea to which genus my find belongs?

Many thanks and greetings

Harald