''Oligosoma nigriplantare'', the Chatham Islands skink, is a species of

skink Skinks are lizards belonging to the family Scincidae, a family in the infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one of the most diverse families of lizards. Ski ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Scincidae. It is the sole reptile species found on the

Chatham Islands The Chatham Islands ( ) (Moriori: ''Rēkohu'', 'Misty Sun'; mi, Wharekauri) are an archipelago in the Pacific Ocean about east of New Zealand's South Island. They are administered as part of New Zealand. The archipelago consists of about te ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

, where it occurs on all the major islands except Chatham Island itself. Given the geological history of the Chatham Islands, it is assumed that ''O. n. nigriplantare'' previously occurred on Chatham Island; however, there are no fossil records or historical reports of ''O. n. nigriplantare'' on Chatham Island. Since ''O. n. nigriplantare'' is almost locally extinct on Pitt Island as a result of introduced mammals, the presence of introduced mammals on Chatham Island might have resulted in the local extinction of ''O. n. nigriplantare''. On vegetated islands, ''O. n. nigriplantare'' inhabits grassland and shrub habitat, but it also occurs on marine rock stacks with sparse vegetation.Freeman A. (2000). "A preliminary study of habitat use in the skink Oligosoma nigriplantare nigriplantare on Rangitira Island, New Zealand". ''Herpetofauna''. 30, 7–10. Substantial morphological variation (body size, colour and colour pattern) is evident within ''O. n. nigriplantare'', potentially indicating morphological evolution following its colonization of the Chatham Islands. Indeed, ''O. n. nigriplantare'' (up to 91 mm Snout to Vent Length; SVL) has a substantially larger body size than '' Oligosoma nigriplantare polychroma'' (up to 77 mm SVL). Recent genetic studies indicate that ''O. n. nigriplantare'' diverged from ''Oligosoma nigriplantare polychroma'' (its nearest relative) 5.86–7.29 million years ago.Liggins, Chapple, Daughertry and Ritchie (2008). "Origin and post-colonization evolution of the Chatham Islands skink ''(Oligosoma nigriplantare nigriplantare'')". ''Molecular Ecology'' 962-1083vol:17 iss:14 pg: 3290-3305. 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.

References

{{Taxonbar, from=Q3013429 nigriplantare Endemic fauna of New Zealand Reptiles described in 1874 Taxa named by Wilhelm Peters Endemic reptiles of New Zealand