Hello Everyone,

I have found perithecia of a black ascomycete embedded just under the epidermis of a dead leaf of Carex riparia. The fruit bodies seem to be growing individually and spaced out along the two edges of the leaf. They measure approximately 0.3 mm diameter.

The spores are brownish green, 1-septate and slightly constricted at the septum. Each cell contains large and small guttules. The spore dimensions range from 19.5 to 25 x 6 - 7 um and there is a hyaline, sharply pointed appendage at each end, each measuring 7 um. The spores and their appendages seem to mostly be slightly curved.

The 8-spored asci seem to radiate from a central area. Spores are arranged in one or two rows inside and lugol distinctly blues the ascus tip. 

I have attached images of the fruit bodies in situ, spores, asci and excipulum.

I wonder if anyone has any ideas as to what this might be?

Thank You,
With Best Wishes,
Peter.