Oligosoma stenotis

Small-eared skink

Oligosoma stenotis
(Patterson & Daugherty, 1994)

Small-eared skink (Stewart Island). <a href="https://www.flickr.com/photos/theylooklikeus">© Jake Osborne</a>
Image attribution
Small-eared skink (Stewart Island). © Jake Osborne
Herpetofaunal category
NZ Skinks
Species complex
Conservation Status
Threatened - Nationally Vulnerable
Common names
Small-eared skink

Length: SVL up to 75mm, with the tail being equal to or longer than the body

Weight: up to 6 grams

Description

A strikingly beautiful, and rare skink from the sub-alpine regions of Stewart Island.

Small-eared skinks are characterised by a distinctive black mid-dorsal stripe edged by yellow, which runs from the neck to the base of the tail, the presence of a keeled tail, and its relatively small ear openings. Upper surfaces are yellow-brown to green-brown, with the aforementioned mid-dorsal stripe, a brown band bordered by cream or yellow stripes is present on the sides. The lower surfaces range from grey-brown to yellow with some individuals having sparse dark flecking.

Distinguished from co-occurring Oligosoma species by the presence of the keeled tail, small ear openings, and the prominent mid-dorsal stripe.

Life Expectancy

Unknown.

Distribution

Confined to the sub-alpine regions of Stewart Island.

Ecology and Habitat

A diurnal species, occurring above the treeline in the sub-alpine zones of Stewart Island. They are often found associated with boulderfield, tussock grassland, and herbfield habitats. It is possible that as with some other species of small South Island skinks that they utilise invertebrate burrows as refugia (pers. comm Tony Jewell).

Social Structure

Solitary.

Breeding Biology

Viviparous. Little is known about their breeding biology, however, when studying the animals for description, one of the study females gave birth to 2 live young in November, indicating either a much earlier breeding season or a much longer gestation period compared with our other skink species. Neonates measure around 26mm SVL, and weigh about 0.2g at birth.

Diet

As with most of our native skinks, this species is omnivorous feeding on both invertebrates (spiders, insects and amphipods), and small fruits.

Disease

Largely unknown, but likely to be a host for several lizard mites and ticks.

Conservation status

Prior to the most recent threat classification, this species was considered to be "naturally uncommon" having a fairly restricted distribution; only occurring in the sub-alpine zones (high altitude herbfields and fractured rock slabs) of  Stewart Island. The implication being that the species had a relatively stable population, due to the ongoing conservation management (pest control) of southern New Zealand dotterel (Charadrius obscurus obscurus) within the skink's preferred habitat. However, according to the most recent threat classification in 2021, opportunistic observations within this habitat suggested that a significant decline had occurred, and thus the threat status was re-assessed to Threatened – Nationally Vulnerable. 

Interesting notes

The small-eared skink's scientific name, much like its common name, refers to the size of the ear opening; stemming from the Greek words stenos meaning "narrow", and otos meaning "ear". 

References

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, 2021New Zealand threat classification series 35. Wellington: New Zealand Department of Conversation.

Hitchmough, R.A., Barr, B., Lettink, M., Monks, J., Reardon, J., Tocher, M., van Winkel, D., Rolfe, J. (2016). Conservation status of New Zealand reptiles, 2015; New Zealand threat classification series 17. Wellington: New Zealand Department of Conservation.

Patterson, G. B., & Daugherty, C. H. (1994). Leiolopisma stenotis, n. sp.,(Reptilia: Lacertilia: Scincidae) from Stewart Island, New Zealand. Journal of the Royal Society of New Zealand24(1), 125-132.

van Winkel, D., Baling, M., & Hitchmough, R. (2018). Reptiles and Amphibians of New Zealand: A Field Guide. Auckland University Press, pp376.