Found this Annulohypoxylon on wood (unknown) in southeast Brazil (São Paulo state), in the same log that I found the Biscogniauxia capnodes (http://www.ascofrance.fr/search_forum/36990) and Pseudocosmospora joca (http://www.ascofrance.fr/search_forum/37055).
Clearly it is an Annulohypoxylon species, since it as a carbonaceous layer surrounding the perithecia, green KOH extractable pigments, ostioles are encircled by an annulate disk, ascospores has a thickened area (shoulder) at of ca. 1/3 spore lenght (from the perispore?).

It has asci with 100-130 x 4.5-5.5 µm and ascospores 6.5-8.0 x 3.2-4 µm.

The closer I was able to go was to A. annulatum, however I would like to hear your opinion about this fungus because I can't go further in the identification since I don't have the necessary literature.
A note that worth be mentioned about this fungus, is that it was found growing both, directly from the bark, but also over Biscogniauxia capnodes (Fig.1).

I would like to take this opportunity to ask if someone has the Ju and Rogers' monograph in pdf
(Ju Y-M, Rogers JD. 1996. A revision of the genus Hypoxylon. Mycologia Mem 20:1–365), and kindly could send it to me.

Thank you very much.

Update: I forgot to mention that the ostiole disk has 0.3-0.4 mm diam.