Very interesting! The species is also known as Leucovribrissea obconica. I have seen it once, but found the spores a little shorter and only 1 µm wide.

You can try to see the amyloid reaction at the margin, also I assume yours lack the crystals I have seen on the exterior of the flanks.

Zotto

Interesting) Did you collect it on "previous year calms of Poaceae"? - so, it may inhabit different substrates?

Yes, there is clear reaction of MLZ in inner layer of excipulum ("perihymenial zone") and no reaction in medullary excipulum.

No crystals, i observed in water and looked at dry apothecia, which may be help, but have not found them (probably, it may depend of wetness of habitat?).

And i tried to improve description of tissues in my specimen, since there are some differences in the drowing in the paper of Beton and Weste (1980), and your drowing, information about excipulum features also provided in Sanches and Korf (1966) for the sections of Vibrissea.

Ectal excipulum from textura angularis-prismatica; at the base cells large, angular, isodiametric, thick-walled, with longitudinal axes perpendicular to the outer surface; in the middle and up to the margin cells in the inner layer becoming elongated, laying parallel to the outer surface and yet thick-walled; outer layer from cells with thinner walls, ellipsoid to prismatic, arranged in rows, with free rejected, hair-like chains from 4-5 cells scattered at all length and densely covering the margin.
Medullary excipulum from textura intricata, hyphae about 2 mk broad; becoming parralel when approaching the excipulum.

I think it worth to draw these tissues when i will be more skillfull in drowings; now prepared some more pictures.

Yet i did not have the last two papers, probably usefull since the key for species is there.

Beaton, G., Weste, G., 1980. Vibrissea: Two North American species redescribed and a new Javan species. Transactions of the British Mycological Society 75, 243–248.
Sanchez, A., Korf, R.P., 1966. The Genus Vibrissea, and the Generic Names Leptosporium, Apostemium, Apostemidium, Gorgoniceps and Ophiogloea. Mycologia 58, 722.
Beaton, G., Weste, G., 1976. Australian discomycetes: Log-inhabiting Vibrissea species. Transactions of the British Mycological Society 67, 129–132.
Beaton, G., Weste, G., 1977. Australian discomycetes: A new Vibrissea species. Transactions of the British Mycological Society 69, 323–325.?

Yes, it was on a monocot, but not collected by myself.

Crystals are usually a good character in the Helotiales, but sometimes they are absent though the species shoul have some.

Here you can download my drawing in better resolution. 

https://www.cubby.com/p/_778a6f3587954e008790666f822f8e4e/7a+Helotiales#7a%20Helotiales/Mollisiaceae/Vibrisseae

There are also macros by Jens Petersen (files 122-Leucovibrissea obconica JHP-10-137-711_07282010.jpg):
Leucovibrissea obconicaNorthern Europe, Bjurälvens naturreservat, (64.927888 / 14.144511), vegetation type: meadow, associated organism: grasses, substrate: stems, grasses, etc., leg.: Thomas Læssøe & Jens H. Petersen, det.: Thomas Læssøe & Jens H. Petersen, coll. number: JHP-10.137.Remarks: sp. 165 x 1 µm.

Zotto

Thank you.

Hi Nina,
You can find the missing papers on the following link:
http://www.cybertruffle.org.uk/cyberliber/index.htm?
Kind regards,

Ivana

Thank you, i simply was not intent in my search, now i have them).