Length: SVL up to 90mm, with the tail being longer than the body length

Weight: up to 8.2 grams

Description

The northern-most member of the speckled skink group, crenulate skinks are one of the larger skink species surviving on the mainland North Island.

Crenulate skinks are tan to dark-brown dorsally with darker lateral stripes, and cream-coloured dorso-lateral stripes / flecking. Occasional melanistic specimens have been found which appear dark grey or blue-grey in colouration.

Crenulate skinks are distinctively patterned and unlikely to be confused with other species where they occur. They are named for their lateral stripes which are either flecked or crenulated at the margins.

Life expectancy

Unknown.

Distribution

Waikato, Bay of Plenty and central North Island.

Ecology and habitat

Crenulate skinks are diurnal and strongly heliothermic. They will sunbask, but often cryptically near cover. 

They occur in a range of habitats from dune systems and boulder beaches on the coast, to open forest, scrub or pasture at inland sites. When not active foraging or basking, crenulate skinks take refuge on the ground under rocks, logs, driftwood, or in dense vegetation.

Social structure

Little is known about the social structure of crenulate skinks, though they are considered to be solitary.

Breeding biology

Largely unknown. On Mokoia Island female crenulate skinks are gravid during spring-summer, and give birth from December to March.

Diet

The diet of crenulate skinks includes a wide range of invertebrates, and the berries / fruit of native species.

Disease

Known to be a host for the ectoparasitic mite Neotrombicula sphenodonti.

Conservation strategy

Crenulate skinks are regarded as At-Risk - Declining. They occur on two pest-free island refuges - Mokoia Island in lake Rotorua and Moutohora/Whale Island off the Whakatane Coast, but are in decline on the mainland where they are exposed to the full suite of introduced predators.

Interesting notes

Crenulate skinks are members of the speckled skink cryptic species complex - a group of related taxa with similar morphology that were previously regarded as one highly variable species, the 'speckled skink' (Oligosoma infrapunctatum).

Individuals from a population south of Hamilton were tag-named Leiolopisma “Ngahinapouri” by Tony Whitaker and Bruce Thomas in the late 1960's and early 1970's. In 1985, Wells & Wellington proposed the species name Oligosoma robinsoni for the Moutohorā  (Whale Island) population in the Bay of Plenty. For several years this species went under the tag name Oligosoma aff. infrapunctatum "crenulate" and their taxonomy was not fully resolved until Melzer et al. published a revision of the speckled skink complex in 2019.

References

Greaves, S. N., Chapple, D. G., Daugherty, C. H., Gleeson, D. M., & Ritchie, P. A. (2008). Genetic divergences pre‐date Pleistocene glacial cycles in the New Zealand speckled skink, Oligosoma infrapunctatum. Journal of biogeography, 35(5), 853-864.

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.

Melzer, S., Hitchmough, R. H., Bell, T., Chapple, D. G., Patterson, G. B. (2019). Lost and Found: Taxonomic revision of the speckled skink (Oligosoma infrapunctatum; Reptilia; Scincidae) species complex from New Zealand reveals a potential cryptic extinction, resurrection of two species, and description of three new species. Zootaxa, 4623 (3), 441–484.

Neilson, K. A. (2002). Evaporative water loss as a restriction on habitat use in endangered New Zealand endemic skinks. Journal of Herpetology, 36(3), 342-348.

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.

Schragen, S., & Perrott, J. (2011). Prevalence of internal parasites of Oligosoma infrapunctatum on Mokoia Island. unpublished Unitec Research Committee Research Report.

Towns, D. R. (1971). The lizards of Whale Island. Tane, 17, 61-65.

Towns, D. R., Neilson, K. A., & Whitaker, A.H. (2002). North Island Oligosoma spp. skink recovery plan 2002–2012: Threatened species recovery plan 48. Wellington: Department of Conservation.

van Winkel, D., Baling, M. & Hitchmough, R. (2018). Reptiles and Amphibians of New Zealand: A Field Guide. Auckland: Auckland University Press, 376 pp.