Hoplodactylus duvaucelii 'southern'

Southern Duvaucel's gecko

Hoplodactylus duvaucelii 'southern'

Southern Duvaucel's geckos. <a href="https://www.instagram.com/nickharker.nz/">© Nick Harker</a>
Image attribution
Southern Duvaucel's geckos. © Nick Harker
Herpetofaunal category
NZ Geckos
Species complex
Conservation Status
At Risk - Relict
Previous scientific names
Hoplodactylus trachyrhynchus
Common names
Southern Duvaucel's gecko

Length: SVL up to 120mm

Weight: Unknown

Description

New Zealand's second largest gecko, and the largest species of gecko in the South Island.

Southern Duvaucel's geckos are large and robust in build. The dorsal colouration may be various shades of grey or olive brown, with a distinctive pale crescent-shaped marking on the nape of the neck, and pale irregular crossbar shaped splotches down the dorsum which continue to the base of the tail. The underside is pale and usually a uniform grey but can be softly speckled / blotched. Duvaucel’s geckos have a pink mouth and tongue. The forehead is slightly concave with yellow eyes, prominent brillar-folds (scales over the eyes), and large oval openings for the ears.

There are significant genetic and morphological differences between southern species (occurring in Cook Strait) and northern species (occurring from the Bay of Plenty northwards). Northern Duvaucel's geckos (Hoplodactylus duvaucelii) are generally much larger, longer (110-161mm SVL) and more robust, with a proportionally longer snout and less-defined markings. Southern Duvaucel's geckos are generally smaller (95-120mm SVL), have a proportionally shorter / blunter snout, a more pronounced brillar fold, and have more well-defined blotched markings. Infralabial scales become gradually smaller in northern Duvaucel's geckos versus often abruptly smaller after the 4th infralabial in southern Duvaucel's geckos.

Southern Duvaucel's geckos will occasionally vocalise which has been described as squeaks, squeals, croaking and coughing.

Life expectancy

Southern Duvaucel's geckos have been reported living over 50 years in the wild.

Distribution

Known only from the Marlborough Sounds / Cook Strait area. Southern Duvaucel's geckos survived only on the Brothers Islands, Trio Islands, and Sentinel Rock. They have since been translocated to two further islands in the Marlborough Sounds and to Mana Island off the south Wellington Coast (outside of their historic range).

Fossil records show that southern Duvaucel's geckos once had a much wider distribution including large parts of the mainland South Island as far south as Otago.

Ecology and habitat

A largely nocturnal species, southern Duvaucel’s geckos can remain active at low temperatures but actively regulate their body temperature by sun basking. During the day they tend to hide in tree hollows, under logs, stones or bark, rock crevices or in petrel burrows.

Social structure

Southern Duvaucel’s geckos are tolerant of members of the same species and may form social aggregations. These groups will usually contain only one male.

Breeding biology

Southern Duvaucel’s geckos give birth to live young and have a low annual reproductive output (maximum of two offspring annually / biennially). Gestation has been variously reported as between five months to longer than a year. Individuals become sexually mature at around seven years old.

Diet

The diet of southern Duvaucel’s geckos is largely insectivorous. However, they will also eat plant material, nectar, and fruit. There are records of Duvaucel’s geckos predating other lizards and the eggs of shearwaters. Southern Duvaucel's geckos have also been reported consuming the berries of Taupata (Coprosma repens) in the wild (Nick Harker pers. obs. 14 January 2020).

Disease

Duvaucel’s geckos are known to harbour a number of ecto- and endoparasites (internal and external).

In the wild, southern Duvaucel's geckos have also been observed with unusual warty growths, the cause of which is currently unknown (Nick Harker, pers. obs. January 2020).

Conservation strategy

Southern Duvaucel's geckos are currently classified as 'At Risk - Nationally Increasing' They have been translocated to two additional islands in the Marlborough Sounds, and also to Mana Island off the south Kapiti / Wellington Coast (the latter being outside of their historic range).

Interesting notes

In the mid 1900's southern Duvaucel's geckos were described as a separate species Rhacodactylus trachyrhynchus (GUIBÉ, 1954), but for a long time have been regarded as a regional variant of the northern Duvaucel's gecko (Hoplodactylus duvaucelii).

Despite being long-recognised as 'different', some researchers felt that the genetic and morphological variation between the northern and southern Duvaucel's gecko species could be accounted for with a north-south cline. However, more recent palaeoecological work, looking at ancient DNA and morphology of Duvaucel's gecko subfossils has provided conclusive evidence that the two groups represent distinct, geographically separated taxa.

References

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.

Jewell, T. (2011). A photographic guide to reptiles and amphibians of New Zealand. Auckland: New Holland Publishing.

Robb, J. (1986). New Zealand Amphibians & Reptiles (Revised). Auckland: Collins, 128 pp.

Scarsbrook, L. (2021). Does Size Matter? Using Osteology and Ancient DNA to Reconstruct Extinct Diversity in Duvaucel’s Gecko (Doctoral dissertation, University of Otago).

Scarsbrook, L., Sherratt, E., Hitchmough, R. A., & Rawlence, N. J. (2021). Skeletal variation in extant species enables systematic identification of New Zealand’s large, subfossil diplodactylids. BMC ecology and evolution21(1), 1-10.

Scarsbrook, L., Sherratt, E., Hitchmough, R., Fordyce, R. E., & Rawlence, N. J. (2021). Unexpected Morphological Diversity in New Zealand’s Large Diplodactylidae Geckos.

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