You must check Phaeosphaeria (Leptosphaeria) monograph of Shoemaker (Can. J. Bot. 1984), or Shoem. & Babc.
There (1984) in the key for determination:

2b.  Spores with  sheath  ..............................................................................  8
.................  80.  Ascocarps  less than 200  mikroms wide.......  9
9tr.  Spores up to 8  mikom wide,  finally  echinulate: on Xeroplryllum ..............................  Leptosphaeria  xerophylli
911.  Spores 8-  11  pm wide,  smooth: on Agastache  ......................................  L. brightonensis.
8b.  Ascocarps more  than  200  mikrom wide   ........................................................  I0.

Try to identify the host plant ...

Hi Susana,

your species is most probably a member of Leptosphaeria. I think it is close to L. doliolum which has typically 3septated spores in pale grey-brown colours.

regards,
björn

hello

For now I can say it's Leptosphaeria sp. Thank you.
L. Doliolum would have the extremes of the spores acute. It could be L.conoidea?
Ascocarp Size: 270 x 220 um
Spores not seen to have ornamentation or sheath
The host, impossible to determine.
Can someone give me the monograph mentioned?

I would also like to get:
SHOEMAKER, R. A. (1984a) - Canadian and some extralimital Leptosphaeria species. Canada. J. Bot. 62: 2688-2729.

regards
Susana

I can send you the documents, no problem.

I am also interested in Shoemakers Leptosphaeria in Can. J. Bot. 62.

regards,
björn

And me too
Thank you
Enrique

Hi all,
I'm also interested in Shoemaker's Phaeopsphaeria monograph :)
Thanks in advance - LUC.

About this sample: it's rather a Phaeosphaeria (peridium rather thin and transluscent) that a Leptosphaeria s.str. (peridium thick and black, not transluscent).