Thank Peter!
Mirek

I think I see blue pigment in epithecium so it should be Hysteropatella elliptica. Hysterium never opens this much when hydrated.

Hello everyone and thank you for your interest in the subject and valuable comments.
As I mentioned, initially I described this collection as a Hysterium pulicare  due to the brighter colored ends of spores. However, I did not know anything about the existence of Hysteropatella elliptica. Yesterday, I found a bit of data about it and I had the impression that morphological features more match this species?
However, as Zotto said, he did not fit a substrate.
Yes, it's definitely Betula (I place a more general photo).

I have one more similar collection also gathered from Betula but I have not yet explored her. However, these grew on the bark, I will post later.
greetings
Mirek

Hi Peter
Do you mean that this is not Betula?
I can only add that the picture is actually not the best. It was made with very cloudy weather. In any case, the bark was white, definitely whiter than in the picture.
Mirek

Hi friends,

First, thanks to Mirek.

In 2011, I collected one fungus on Betula, kept in herbarium under the name Hysterium sp. cf pulicare. There were many hysterothecia, densely packed against each other, and if I well remember, elongated, not like H. pulicare that is morphological variable.  It was observed on decorticated wood, next to, and under the bark, like Mirek's ones.

I can look at it again, if necessary. Microscopy was like Mirek's one.

Alain

Hi Zotto,

I will check it, Keep in touch, please.

Alain

As a complement to the discussion, I place photos of another collection, which I mentioned before.
Ascomata grew on a birch bark, on a trunk after a cut tree.
I place more photos of spores showing their various.

Their dimensions:
(18.6) 21.2 - 24.4 (24.8) × (5.2) 6 - 6.9 (7.5) ?m
Q = (2.9) 3.2 - 3.8 (4); N = 15
Me = 22.6 × 6.4 ?m; QE = 3.5

24.36 6.06
21.17 5.24
21.55 6.57
22.74 6.03
22.58 6.34
18.64 5.78
23.21 7.48
23.07 6.94
21/06 7.15
24.79 6.58
22.99 6.41
22.75 6.79
22.27 6.43
23.28 6.07
24.45 6.85

Comments are welcome :)
greetings
Mirek

The ascomata of this find remain too closed and show ridges on the hymenium when exposed, also the outsde is with longitudinal striation. All this I remember to be typical of Hysterium. This is not a Hysteropatella.

Thank you Zotto
Mirek