Hi there,

it looks like your needles are trash needles (those which have died prematurely as the branch has been broken) and not senesced litter needles (died of old age). If they are the former and if your host is Scots Pine, then it might either be L. conigenum or L. seditiosum. You then need to look at your sections and look for displaced epidermal cells (the ascomata are more or less sub epidermal but a few cells get left at the base of the ascomata depending on the species). If thereare none then it is L.seditiosum and if there are a few (less than 7)scattered about then it will be L. conigenum. This information is from David Minter's amazing studies on Lophodermium!
Cheers,
Jo

Hi Joanne,
Thanks for your message.
I'm afraid to not understood completely the meaning of the displaced cells as you call them. Thus, I upload the (bad) section I took from microscopy. Where in the photo I should look for those cells? 
Best Regards,
zaca

I can't make them out in your picture, it usually requires a pretty thin vertical section.  Sectioning air-dried specimens with a safety razor blade is often easier than sectioning fresh specimens.

Minter describes and illustrates the concept of displaced epidermal cells in:

Minter, D. W., Staley, J. M., & Millar, C. S. (1978). Four species of Lophodermium on Pinus sylvestris. Transactions of the British Mycological Society, 71(2), 295-301.

Minter, D.W., 1981. Lophodermium on pines. Commonwealth Mycological Institute.

It relates to how the ascoma is embedded in the host tissue.  It took me a bit of time to learn how to readily identify this character; collecting and comparing different subcuticular and subepidermal Lophodermium species helped.

Of course there are cryptic species complexes in Lophodermium, which makes identification somewhat tenuous for some species...

Thanks, Joey,
for your comments and references.
I will try to get some literature on the genus and, maybe make a better section.
Best regards,
zaca

Hi again,
The needles are ver britle, making difficult to make good sections. I attached my best result, from where I could not see any "displaced cells" from the ascoma left on the substrate.
Cordialment,
zaca

Hi Zaca,
this is not often simple to determine this species.
I have sent some literature.
Greetings Peter.