I would say it is neither Kretzschmaria (definitely) nor Nemania serpens (also definitely). It could well be Annulohypoxylon cohaerens as Enrique says but I would not exclude Hypoxylon spec., e.g. H. fragiforme. In this (quite unripe) stage it is quite difficult to say much without using KOH - the colour of the soluble pigments would help!

Regards from Lothar 

Hello together,

yes, the papillate ostioli are a clear sign.

But - A. cohaerens and H. fragiforme often grow together and - especially on the front face of lying logs - H. fragiforme and A. cohaerens can look very similar in first appearance at first glance. They commonly grow together there and if they are still unripe and young (without ostioli) it is often quite impossible to say without KOH which one is developing. They also grow together on the bark where A. cohaerens is very common, too, like H. fragiforme on bare wood.

Best regards, Lothar

It is A. cohaerens - the perithecia are papillate (I overlooked this first).

But H. fragiforme (and possibly other Hypoxylon species) can look very similar by first glance.

Best regards from Lothar