I don't know about true range of this species, you can add the missing one by editing the taxon, you'll find the link "add range" or the like at the editing-page of taxa.
Have not done this myself till now, you might try to do this.

Later addition:
All right, i think you talked about the map we can watch or hide at taxon profiles.
As you said this could have been changed by a taxon-swap, don't know this just guessing.
There is a link to edit the range, but i don't know what and how to edit there, sorry this helps nothing at all.

For now I deleted it. Perhaps in the future the admin can do an import of ranges for the taxa that are missing them. (fyi @loarie)