Oedohysterium sinense

The fruit body is black, hard, generally 0.5-2 millimetres in length, much narrower than long, not taller than wide and with a fissure running along the length of the fruit body. The fruit bodies usually appear in large groups. Technically this type of fruit body is called a hysterothecium and hysterothecial fungi are ascomycetes. Hysterothecial fungi are fairly common but easily overlooked. Often you find them on hard, weathered wood in exposed habitats (e.g. on old wooden fence-posts, power poles or paling fences).

Oedohysterium sinense is a cosmopolitan species.

Look-alikes

There are about a dozen genera in the families Hysteriaceae and Gloniaceae with such hysterothecia and identification of genera relies heavily on spore features.

The features of Oedohysterium are: Spores brown and commonly with at least 6-8 cross-wise septa and with a swollen cell alongside the near-central constriction. Closest to Oedohysterium sinense (spores mostly 38-50 x 11-15 microns) is Oedohysterium insidiens (spores mostly 23-28 x 7-10 microns), another cosmopolitan species.    

Other hysterothecial genera on Canberra Nature Map

Gloniopsis

Hysterium

Hysterobrevium