The New Zealand skink fauna is diverse, comprising at least 28 species in two endemic genera, Oligosoma and Cyclodina (Daugherty et al., 1994; Gill and Whitaker, 2001). The taxonomy of New Zealand skinks has been problematic, complicated by cryptic species, overlapping morphological characters among species, and wide variation within many species across their ranges (Hardy, 1977). There is no comprehensive molecular phylogeny for New Zealand skinks, so many species remain undescribed, and the origin and evolutionary history of the fauna remain largely unknown. For example, the age of the entire New Zealand skink fauna has been variously dated to the Pliocene, the Miocene and the Oligocene (reviewed in Smith et al., 2007).
Greaves, S., Chapple, D., Gleeson, D., Daugherty, C., & Ritchie, P. (2007). Phylogeography of the spotted skink (Oligosoma lineoocellatum) and green skink (O. chloronoton) species complex (Lacertilia: Scincidae) in New Zealand reveals pre-Pleistocene divergence. Molecular Phylogenetics and Evolution, 45, 729 - 739. https://doi.org/10.1016/j.ympev.2007.06.008