Orophe unicus is a species of millipede in the family Xystodesmidae, which is found in the Rocky Mountains of northern Idaho.

[3] Hoffman also suggested that the differences in the gonopods of O. unicus and O. cabinetus were minor and so the relationship between the two may be "subspecific".

[4] In 1993, Rowland Shelley reexamined the type specimens and based on the differences in the gonopods as well as the allopatric nature of the two populations, reinstated O. unicus as a valid species.

The two species are only differentiated by a slight difference in the structure of gonopod and by their range, with O. unicus occurring in northern Idaho.

The paranota also arise low on the segments and are noticeably depressed, giving the millipede a domed appearance.