Oligosoma aff. polychroma Clade 5

Southern grass skink

Oligosoma aff. polychroma Clade 5

Southern grass skinks. <a href="https://www.instagram.com/samanimalman/?hl=en">© Samuel Purdie</a>
Image attribution
Southern grass skinks variation. © Samuel Purdie
Herpetofaunal category
NZ Skinks
Species complex
Conservation Status
At Risk - Declining
Previous scientific names
Oligosoma polychroma,
Oligosoma nigriplantare polychroma.
Common names
Southern grass skink,
Common skink.

Length: SVL up to 80mm, with the tail being equal to or slightly longer than the body length

Weight: unknown

Description

A very sleek and variable species of grass skink with a snout-vent-length (SVL) up to 80 mm. Southern grass skinks typically have a tan-brown dorsal surface with a dark mid dorsal stripe extending down the tail and conspicuous pale dorsolateral stripes that can be smooth or notched. This species possesses a dark brown lateral band with smooth or notched borders that are usually pale. The ventral surface, including throat and chin, is typically uniform grey, brown, tan-brown, cream, white or yellow. Eye colour is typically brown-tan, sometimes slightly green. This species usually possess a pale stripe on the forelimbs. Subdigital lamellae 16-24 (van Winkel et al. 2018; Jewell 2008) . 

Life expectancy

Unknown.

Distribution

A very widespread species of grass skink. Found in Otago, Southland, Central and southern Canterbury (incl. on Banks Peninsula), and Foveaux Strait (incl. Stewart Island). This species is also found at a variety of elevations from lowland coastal areas, right up into the mountains. 

Ecology and habitat

Southern grass skinks are a very frequently seen species because they are diurnal, avid sun-baskers, and terrestrial. This species has been recorded in densities as high as 4000 per hectare (Wilson et al. 2017). Southern grass skinks inhabit a range of habitats including coastal dune habitat, wetlands, grassland, shrublands, rocky shrubland/herbfield, screes, tussock, stony river beds and even cities.

Social structure

Unknown.

Breeding biology

This species reproduces annually and is mature at about 3 years old. Mating likely takes place around March, with 3-6 offspring born in the summer months (November-February) (van Winkel et al. 2018).

Diet

Feeds on small invertebrates and small fruits/sugar sources. 

Disease

Unknown. 

Conservation strategy

This species is not being actively managed. However, when land is developed/destroyed, this species is often salvaged and relocated to suitable habitat. This species is also present at a number of predator-resistant sanctuaries. 

Interesting notes

This species has been observed occupying insect burrows.

Southern grass skinks are members of a cryptic species complex which includes the northern grass skink (Oligosoma polychroma), Waiharakeke grass skink (Oligosoma aff. polychroma Clade 2), south Marlborough grass skink (Oligosoma aff. polychroma Clade 3), and Canterbury grass skink (Oligosoma aff. polychroma Clade 4). The various species are regionally distributed, similar in both appearance and habit, and were once regarded as a single highly variable species - the 'common skink'. There are currently no known morphological features to distinguish southern grass skinks from the other species within the complex. 

References

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

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

Wilson, D. J., Mulvey, R. L., Clarke, D. A., & Reardon, J. T. (2017). Assessing and comparing population densities and indices of skinks under three predator management regimes. New Zealand Journal of Ecology41(1), 84-97.