 This pre-dates the emergence date for the Chatham Islands, but indicates that "O. n. nigriplantare" colonized the Chatham Islands via overwater dispersal on a single occasion.There is substantial morphological variability evident in "O. n. nigriplantare", and a shallow level of genetic differential between islands within the Chatham Islands indicating low gene flow between islands, but not speciation between islands.The level of genetic and morphological divergence between "O. n. nigriplantare" and "Oligosoma nigriplantare polychroma" might warrant their recognition as distinct species.