Length: SVL up to 86mm, with the tail being equal to or longer than the body length

Weight: up to 6 grams

Description

A beautifully patterned skink comprising a variety of geographic forms. Some of the forms in the complex may represent variation within a single species. However, some forms possess distinct morphological features, unique genetics, and occupy different niches/ are geographically separated. Consequently, it is probable that some of these geographic forms represent unique species, which are yet to be formally described. There is some debate, however, as to whether these are in fact, unique species (Chapple et al. 2011; Patterson 2011).

Cryptic skink: Mid to dark brown dorsal surface uniform or speckled with pale or dark flecks. Typically has a dark mid-dorsal stripe. Lateral surfaces bear a vivid dark lateral band, which is typically bordered with a pale-cream notched or smooth dorsolateral stripe. Chin and throat grey or yellowish, sometimes flecked with black. 60-75 mm SVL.

Herbfield skink: Dorsal surface glossy brown with dark mid-dorsal stripe. Lateral surfaces typically bear relatively smooth and bright pale cream dorsolateral and mid-lateral stripes. Ventral surface pale to yellowish, similar to cryptic skink. 

(Jewell 2019; Jewell 2008)

Life expectancy

Unknown.

Distribution

Cryptic skink: Found in the lowlands around Lake Wakatipu, Eyre Mountains, Thompson Mountains, Livingstone Mountains, Southland, Raratoka and Pig Islands in Foveaux Strait.

Herbfield skink: Known from lowland habitat in the Southland Plains (incl. Tiwai Point wetlands), Eastern Otago from the Aparima River to the Shag River. Can be found in the Dunedin area, Macraes Flat, and Wairio. 

Ecology and habitat

Cryptic skinks may differ in habitat use and ecology depending on geographic form, however, their habitat use and behavior is ultimately somewhat similar. These skinks are diurnal and terrestrial (occasionally semi-arboreal climbing into tall shrubs). While they do sun bask, they typically do so in a cryptic manner, while hiding in dense vegetation or near the entrance to their stone retreats. Consequently, they can sometimes be difficult to observe basking. These skinks have been recorded in a variety of habitats from the lowland right up to at least 1825 m (a.s.l). They exist in habitats such as tussocklands, grasslands, scrublands, herbfields, wetlands, and rocky areas (e.g. rocky beaches, shrubland, screes, tallus, vertical rock walls)(van Winkel et al. 2018).

Social structure

Laregly unknown. However, some have been seen in remarkably high densities (such as herbfield skinks), while others appear to be more solitary, or are lower in density (such as Oteake skinks and mahogany skinks).

Breeding biology

Poorly understood. Females produce 1-3 young annually (at least in lowland areas) in summer (January-March).

Diet

Cryptic skinks feed on small invertebrates and on the fruits of native shrubs, and the nectar of flowers.

Disease

Unknown. 

Conservation strategy

This species is not being actively managed, but taxonomic and genetic work is currently underway which will help to inform and protect populations that may be distinct species in their own right. Three populations of cryptic skink exist on predator-free Islands (Centre Island, Pig Island in Foveaux Strait and Tree Island in Lake Wakatipu), and at least one population of herbfield skinks exist in a predator-resistant environment (Ōrokonui Ecosanctuary, Dunedin). Additionally, surveys for poorly known forms such as Oteake skink are being conducted to try learn more about the distribution of this potentially threatened species. 

References

Chapple, D. G., Bell, T. P., Chapple, S. N., Miller, K. A., Daugherty, C. H., & Patterson, G. B. (2011). Phylogeography and taxonomic revision of the New Zealand cryptic skink (Oligosoma inconspicuum; Reptilia: Scincidae) species complex. Zootaxa, 2782(1), 1-33.

Chapple, D. G., Ritchie, P. A., & Daugherty, C. H. (2009). Origin, diversification, and systematics of the New Zealand skink fauna (Reptilia: Scincidae). Molecular phylogenetics and evolution, 52(2), 470-487.

Cree, A. (1994). Low annual reproductive output in female reptiles from New Zealand. New Zealand journal of zoology, 21(4), 351-372.

Daugherty, C. H., Patterson, G. B., Thorn, C. J., & French, D. C. (1990). Differentiation of the members of the New Zealand Leiolopisma nigriplantare species complex (Lacertilia: Scincidae). Herpetological monographs, 61-76.

Hitchmough, R., Barr, B., Knox, C., Lettink, M., Monks, J. M., Patterson, G. B., Reardon, J. T., van Winkel, D., Rolfe, J., & Michel, P. (2021). Conservation status of New Zealand reptiles, 2021. New Zealand threat classification series 35. Wellington: New Zealand Department of Conversation.

Jewell, T. (2008). A photographic guide to reptiles and amphibians of New Zealand. Auckland: New Holland.

Jewell, T. (2019). Skinks of southern New Zealand. A field guide. Edition 4. 

Jewell, T. (2022). Oligosoma murihiku n. sp. (Reptilia: Scincidae) from the south-eastern South Island of New Zealand. Jewell Publications, Occasional Publication #2022C.

Jewell, T. (2022). Oligosoma pluvialis n. sp. (Reptilia: Scincidae) from Te Wāhipounamu/South West New Zealand. Jewell Publications, Occasional Publication #2022H.

O’Donnell, C. F., Weston, K. A., & Monks, J. M. (2017). Impacts of introduced mammalian predators on New Zealand’s alpine fauna. New Zealand Journal of Ecology, 41(1), 1-22.

Patterson, G. B., & Daugherty, C. H. (1990). Four new species and one new subspecies of skinks, genus Leiolopisma (Reptilia: Lacertilia: Scincidae) from New Zealand. Journal of the Royal Society of New Zealand, 20(1), 65-84.

Patterson, G. B., & Daugherty, C. H. (1995). Reinstatement of the genus Oligosoma (Reptilia: Lacertilia: Scincidae). Journal of the Royal Society of New Zealand, 25(3), 327-331.

van Winkel, D., Baling, M., Hitchmough, R. 2018. Reptiles and amphibians of New Zealand – a field guide. Auckland university press, Auckland New Zealand.

Wotton, D. M., Drake, D. R., Powlesland, R. G., & Ladley, J. J. (2016). The role of lizards as seed dispersers in New Zealand. Journal of the Royal Society of New Zealand, 46(1), 40-65.