North Bohemia, wet rotten wood of Salix, about 300 m a.s.l.
Ascospores 4.1-5.1 (5.4) × 1.2-1.5(1.6) µm, Q = (2.7) 2.8 - 3.9 (4.1)
Asci 8-spored, 37-41 x 3.3-3.9 µm.
Conidia 3-septate, not branched, 16-21.5 × 4.8-5.5 µm
Paraphyses capitate, apex covered with an exudate, the last cell 13.7-23.7 × 2.3-4.3 µm
Margin is beset by septate elements (hairs?), the last cell is 16.9-22.4 × 3.4-4 µm, these continue with bent glassy processes which have a rough surface.
SCBs - I haven´t seen any.
North Bohemia, wet rotten wood of Salix, about 300 m a.s.l.

The most similar species seem to belong to the series Drechslerella, but I haven´t found anything fully fitting.
Thanks for your help, Zuzana

Zuzana Sochorová (Egertová), 20-09-2021 17:32

Re : White, small-spored Orbilia

some more photos

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Zuzana Sochorová (Egertová), 20-09-2021 18:32

Re : White, small-spored Orbilia

Some more photos - asci and separated glassy processes.

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Zuzana Sochorová (Egertová), 20-09-2021 20:21

Re : White, small-spored Orbilia

Here is a small comparison of the Czech find and other species of the series Drechslerella.

Pilosa – smaller spores, glassy processes absent
Flavovacuolata – smaller apothecia, longer spores, glassy processes absent
Polybrocha – a bit longer spores, apothecia often brown
Naumburgensis – spores OK, but bent conidia
Yunnanensis – smaller spores, glassy processes can be almost absent
Orientalis - smaller spores
Brochopaga – smaller spores, exudate absent
Tonghaiensis – smaller spores with very different shape

Am I searching in a wrong series?

Hans-Otto Baral, 21-09-2021 11:06

Re : White, small-spored Orbilia

It is not very clear but I feel the spore bode is rod-shaped and strongly eccentrical, visible in some spores. (it depends on the side of view).

My first guess would be a pale form of O. polybrocha (= Patinella tenebricosa), but the spores should be *5-6.5 x 1.1-1.3 µm.

O. naumburgensis would be a good choice, apo size and colour would fit. You have any macrophotos?

The 3-celled spores I cannot be sure. Obviously they are conidia, but  whether they are orbiliaceous oir even belong to the apos is uncertain.

Zotto

Zuzana Sochorová (Egertová), 21-09-2021 11:22

Re : White, small-spored Orbilia

Hi Zotto,
thank you very much for your answer. 
I don´t have any macro yet (my husband went to a Rubus expedition and needed to take the camera with him), but hopefully I will add photos of apothecia tomorrow, the fungi are in a fridge.
I though the conidia belong to the apothecia, because they are similar to those occurring in the series Drechslerella.
Sorry for the quality of pictures - the microscopic characters in Orbilia are too small for my home equipment.
Zuzana

Zuzana Sochorová (Egertová), 22-09-2021 17:34

Re : White, small-spored Orbilia

Photos of apothecia. They are shortly stipitate.

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Hans-Otto Baral, 22-09-2021 19:37

Re : White, small-spored Orbilia

It reminds me of O. naumburgensis but also orientalis. Either of these or a third unknown species. Drechslerella is very complex, but resolvable with ITS.

The conidia might really be true, they closely resemble short ones in HB 9895a from Serbia.

Salix is certain? Was it a log?

Zuzana Sochorová (Egertová), 22-09-2021 19:51

Re : White, small-spored Orbilia

Thank you, Zotto. 
Salix is certain, is was a whole tree :-) If I remember well, there is no other tree species in this part of the locality. Orbilia was growing on the stem (I think a place where a strong twig was cut), it a height of maybe 1.3 m. I will verify it next time I visit the locality (which should be in a month or two).
I will ask Michal to try to obtain ITS.