Xylobosca canina

There is  strong sexual dimorphism observed in this genus; males are much shorter, and the apex of elytra is differently shaped, with long spines.

canina female 5mm
this may have been described as  Xylobosca leai.  Males and females were described separately.
Late July 2016
This must have emerged from a blackwood branch.
Identification and preliminary information thanks to Boris Büche

Varied females on dead branches

Xylobosca canina male
Early August 2016
Emerging from Blackwood timber