Hi Lothar,
Mycobilimbia pilularis fits quite well, since the macro coincides with your description and the spores are predominantly 1-septate, fusiform-ellipsoid, with dimensions (9.5-)11.5-13.9(-17) x (3.0)4.2-4.3(-5)um. In addition, it uses to grow on Fraxinus and Quercus (maybe others).
Have a look at
http://www.irishlichens.ie/pages-lichen/l-356.html
Best regards,
zaca

Hi Zaca,

thank you very much for your rapid answer!

In Wirth (1995 - "Die Flechten Baden-Württembergs") M. pilularis (Körber) Hepp is included as a synonym in M. sphaeroides (Dickson).

In Wirth (1980 - "Flechtenflora" - UTB Ulmer) a "pilularis" is not included, and Bacidia sphaeroides (Dickson) Zahlbr. is keyed out (page 131) with "sp. 4(-6)-celled, 12-25/4-7"

I do not have further literature on this topic.

So what?

Best regards from Lothar

I just looked in Index of Fungi

Biatora sphaeroides = Mycobilimbia pilularis

 

Hi Zaca,

where do you take the information about predominantly 1-septate spores? I do not find this on "Irishlichens". Am I only blind? ...

Thanks and best regards, Lothar

The data I mentioned is from
The Lichens of Great Britain and Ireland, Smith et al., 2009, BLS;
where Bacidia sphaeroides does not appear. I'm not very familiar with these species, so I can not say anything valuable.
Good luck,
zaca

Hi Zaca,

thank you very much anyway.

I jus found another book in my library :-):

Dobson, F.S. (2011, 6th edition): Lichens. An illustrated guid to the British and Irish species.

So - there I find (on page 281): Mycobilimbia pilularis (= Biatora sphaeroides). And the text: "Spores 1-septate (with a few older spores 3-septate)."

I can find my specimen within this :-)

So I think the determination can be kept - but still I do not know what name is to be used ...

Best regards from Lothar

 

Best regards, Lothar