In an earlier molecular phylogenetic study, a sample of what was originally identified as Cryptantha hispida (Boraginaceae) from Chile, grouped with species of the genus Johnstonella. This sample was subsequently shown not to be C. hispida, but an undescribed species, endemic to the dry Puna of Chile. This new species is described here as Johnstonella punensis, along with a key to all South American species of the genus. Johnstonella punensis resembles other members of that genus in having an ovate fruit shape, ovate nutlets and a long style that extends beyond the nutlets. It is unusual in the genus in having a non-tuberculate, dimpled to rugulose nutlet surface sculpturing. Its closest relative within the genus is likely the South American J. diplotricha.