https://www.inaturalist.org/observations/44472975

The only known Syntonus species of Australia is Syntonus venus. But this species has a very different forceps. There is no other possible known species for Australia, leaving it as an introduced species or undescribed native one. permico identified it as Syntonus, with agreements by matthew_connors and me.

matthew_connors wrote on iNat:
Mt Lewis is the sort of place where this could easily be a native species though. There are hundreds of short-range endemics that essentially only live on this one mountain, and it's not exactly the sort of place I would expect to find something introduced.
[...]
[i]I found one finally! I agree it appears to be a Syntonus - structurally the front half of the body at least is the same, just the cerci and the pair of spines near the end of the abdomen is different.