This species is very similar to Russalpia albertisi.
According to Key (1991) they can be distinguished by two features:
In R. longifurca the male femora I and II are slightly to strongly inflated.

In R. albertisi the male furcula is absent or short and blunt:

In R. longifurca the male furcula is present and has long sharp arms:

The two species are geographically separated, R. albertisi occurring in the north and east and R. longifurca to the southwest.
Key (1991) describes dividing lines as follows, “a line proceeding eastwards from the western coast to the vicinity of Lake Rowallan, and then south to just west of Derwent Bridge , between Mt Field West and Mt Mueller, and on the south coast near Prion Bay. North of Cradle Valley the two species are separated by only c. 3 km … and west of Derwent Bridge also by c. 3 km”
For the purposes of iNaturalist I believe that observations clearly away from the line can be identified to species by location. Near the line a good image of male genitalia is needed.

REFERENCE
Key, 1991 “On Four Endemic Genera of Tasmanian Acrididae (Orthoptera), Invertebr. Taxon., 1991, 5, p. 241-88

Although this species is included the Guide to Australia Grasshoppers and Locusts there are problems with the entry.
The photo is the same as that under U. erythrocnemis.
Some or all of the text seems also to be for the wrong species.
Generally the pronotum of this species is rough, hence the specific name.

Colour and pattern are quite variable, see images in this project. Sjostedt described some specimens as a different species and one as a different genus.
The similar U. guttulosa can be distinguished by its purple hind tibia.
U. erythrocnemis appears to have a distinct range and has a smooth pronotum (Rentz et al. 2003)
The range of U. sp. 1 overlaps with U. rugosa in south eastern SA. It has large tubercules on the pronotum.

REFERENCES
Rentz, D.C.F, Lewis, R.C., Su, Y.N., Upton, M.S, 2003 "A Guide to Australian Grasshoppers and Locusts", publ. Natural History Publications (Borneo)