Its a true species, some have decided that it is the PNG species T dendrophloia (spelling?). I think that it is a seperate species. It is rather different to T. hillii.
I have seen it in the rainforests just west of Cape Tribulation, rather common in a small area north of the Daintree River.
I have one on a trellis at home which has grown amazingly well in NE NSW.
Certainly not a northern 'form' of hillii- I guess it depends on your definition of 'species' and 'form'
From Kris

Kris

Many Many thanks for the info.

Nathan