Resembles Amorbus obscuricornis; distinguishing features are outlined at https://tasmanianinsectfieldguide.com/hexapoda/insectsoftasmaniahemiptera/suborder-heteroptera/infraorder-pentatomomorpha/superfamily-coreoidea/coreidae-leaf-footed-squash-bugs/genus-gelonus/gelonus-tasmanicus/
Gelonus tasmanicus is listed in the following regions:
Canberra & Southern Tablelands | Southern Highlands | Tasmania