NEW ZEALAND'S KAWEKAWEAU AND DELCOURT'S UNIQUE MEGA-GECKO - THE REMARKABLE HISTORY OF AN ONGOING HERPETOLOGICAL MYSTERY

Are Delcourt's giant gecko and New Zealand's mythical kawekaweau one and the same? (© Markus Bühler)

The largest species of gecko known to exist today in New Zealand is Duvaucel's gecko Hoplodactylus duvaucelii, which attains a total length (snout-tip to tail-tip) of up to 12 in.

Just over a century ago, however, a much more sizeable species may have still survived here - if the evidence presented by a unique and truly extraordinary taxiderm specimen is anything to go by – and may even still do so today. I documented this fascinating case within my book The Encyclopaedia of New and Rediscovered Animals (2012) as follows:

Duvaucel's gecko Hoplodactylus duvaucelii (© Jennifer Moore/Wikipedia - CC BY 3.0 licence)

The history of this mysterious taxiderm mega-lizard began sometime between 1833 and 1869, because that was the period during which France's Marseilles Natural History Museum had received a specimen of a very unusual lizard from an unrecorded locality. As a mounted taxiderm exhibit, it was subsequently put on open display at the museum - where, for many years, it remained in full view of countless numbers of visitors, not to mention generations of museum scientists and many others who passed through from elsewhere. Yet, unbelievably, never once in all that time did anyone realise, or even suspect, that it belonged to a dramatically new species - one that had never been recorded by science!

The decades rolled by, but still the ignored lizard's true identity remained undisclosed and uninvestigated - until as recently as 1979, when this strange specimen attracted the curiosity of the museum's herpetology curator, Alain Delcourt. Eager to learn more about it, Delcourt took some photographs, and along with the specimen's measurements he sent them for identification to a number of reptile experts around the world.

New Caledonian giant forest gecko Rhacodactylus leachianus (© Alfeus Liman/Wikipedia – free use permitted with copyright holder attribution)

They ultimately reached Canadian biologist Dr Anthony P. Russell, who in turn showed them to Villanova University herpetologist Dr Aaron M. Bauer. Russell and Bauer recognised that the specimen was clearly a gecko, but of grotesquely gigantic proportions, measuring fractionally over 2 ft in total length. (This is 54 per cent larger than the world's next biggest species of modern-day gecko, the New Caledonian giant forest gecko Rhacodactylus leachianus.) It was a short-headed, bulky-bodied creature, with sturdy legs and a long pointed tail, and was handsomely marked along its back with dark reddish-brown, longitudinal stripes overlying its yellowish-brown background colouration. In overall appearance, it compared fairly closely with geckos of the genus Hoplodactylus - except, once again, for its huge size.

The existence of this enigmatic lizard finally became known to the world at large in 1984, when Bauer's investigations of its possible origin led him to New Zealand. And in 1986 its species was formally described by Bauer and Russell, who named it Hoplodactylus delcourti - in recognition of Delcourt's laudable action in rescuing this long-neglected form from more than a century's worth of zoological obscurity.

Delcourt's giant gecko, the only known specimen, viewed ventally (left) and dorsally (right) (© International Society of Cryptozoology and Dr Aaron Bauer – reproduced here on a strictly educational, non-commercial Fair Use basis only)

Its identification as a Hoplodactylus species had provided an important indication to its likely origin, because this genus's species are mostly limited to New Zealand, thus implying very strongly that this was also the home of the giant H. delcourti. Extra support for this conclusion came from Bauer's investigations here, because he learnt that Maori legends spoke of a strange New Zealand creature called the kawekaweau or kaweau. No-one had previously succeeded in identifying this mysterious animal with any known species inhabiting New Zealand, but various reports from the 19th Century described alleged encounters with such creatures.

One of the most detailed of these accounts, documented in 1873 by W. Mair, reported the killing of a kawekaweau three years earlier in North Island's Waimana Valley by a Urewera Maori chief. He had informed Mair that it was a large forest-dwelling lizard about 2 ft long, as thick as a man's wrist, and brown in colour with red longitudinal stripes. This description is a near-perfect match with that of Delcourt's giant gecko.

Dorsal view of the model of Delcourt's giant gecko featuring in the exhibition 'The Dear Departed' that was presented in 2000 by Lille Natural History Museum (© Lamiot-Wikipedia - CC BY-SA 4.0 licence)

Bauer and Russell thus believe that the kawekaweau and H. delcourti may indeed be one and the same. Sadly, however, there seems little hope that this can ever be conclusively tested, because it is almost certain that H. delcourti has been extinct for many years. How ironic, that a species as striking as this one should vanish into oblivion while a specimen was actually on public display for many years at a renowned natural history museum.

Or has it really vanished? Wellington's Dominion newspaper reported on 11 September 1984 that Wellington resident Dave Smith allegedly saw one on the western portion of North Island in the 1960s! Also, following a New Zealand radio programme broadcast on 23 March 1990 in which this species' remarkable history was recounted by James Mack, assistant curator of New Zealand's National Museum, the museum was contacted by several people who claimed to have spied living specimens of H. delcourti in recent times. The eyewitness accounts included three independent, reliable sightings all made at the same locality near Gisborne, on North Island's eastern coast.

Drawing of a kawekaweau eating a weta (© Hodari Nundu)

These, and various other reports, were followed up by herpetologist Anthony Whittaker and government scientist Bruce Thomas, but without success. Nevertheless, Whittaker believes that this species might still survive in the remote East Cape Forests. Perhaps, after all, there will come a time when Delcourt's giant gecko will be known from more than just a single, long-forgotten taxiderm exhibit.

And that is where I concluded my coverage of this enigmatic species and specimen within my book on new and rediscovered animals; but during the years since then, I have uncovered some very intriguing additional, relevant information, so here it is.

Tuatara (public domain)

The kawekaweau is not the only extra-large mystery lizard on record from New Zealand. Most famous are the taniwha – New Zealand's very own dragons. Looking somewhat like gigantic gecko lizards, or even colossal tuataras Sphenodon punctatus (those primitive superficially lizard-like reptiles endemic to New Zealand but belonging to an otherwise exclusively prehistoric reptilian lineage known as the rhynchocephalians), and bearing a row of long sharp spines along the centre of their back, taniwha are still seriously believed in even today by the Maori people, and are said to have formidable supernatural powers.

In 2002, a major highway in New Zealand had to be rerouted because of Maori claims that it would otherwise intrude upon the abode of a taniwha. Even more recently, in 2012, a similar objection arose in relation to the planned $2.6 billion construction of a tunnel in Auckland, with protestors claiming that this would disturb a taniwha that lived under the city.

Taniwha carving (public domain)

Auckland notwithstanding, these formidable creatures normally inhabited dark, secluded localities on land, as well as in large freshwater pools, and sometimes in the sea too, and were reputedly able to tunnel directly through the earth, often causing floods or landslides as a result. Each taniwha was allied to a specific Maori tribe that it protected as long as it received a fitting level of respect and veneration, but it would often attack and devour members of other tribes.

Also present in Maori traditions are the ngarara – giant lizard-like land dragons seemingly resembling monitor lizards (even though these are not known to be native to New Zealand). Various ngarara could assume the form of a beautiful young woman (as could some taniwha).

Ngarara portrayed upon a postage stamp issued by New Zealand in 2000 (© New Zealand postal services, reproduced here on a strictly educational, non-commercial Fair Use basis only)

Yet another giant mystery lizard of New Zealand is the kumi. Although occurring chiefly in Maori folklore, a real-life example was reportedly encountered near Gisborne in 1898 by a Maori bushman. He claimed that it was around 4.5 ft long, and that it clambered up into a rata tree, leaving behind some footprints on the ground, which were apparently seen by other observers too.

Could it be that in distant ages, giant lizards really did exist here, a land famous for its absence of terrestrial carnivores prior to humankind's introduction of rats, cats, and dogs? Certainly there was a vacant ecological niche for such an animal form, but without physical evidence of any erstwhile presence, such as preserved or skeletal remains, this intriguing line of speculation must remain exactly that – speculation.

Front view of the model of Delcourt's giant gecko featuring in the exhibition 'The Dear Departed' that was presented in 2000 by Lille Natural History Museum (© Lamiot-Wikipedia - CC BY-SA 4.0 licence)

All of which brings us back very appositely to Delcourt's giant gecko, because, very remarkably, there is actually no – or next to no – tangible evidence to confirm that it ever did (let alone still does) exist in New Zealand. Indeed, this anomalous paucity of physical remains for H. delcourti here is such that certain researchers have aired the view that perhaps the zoological world has been wrong all along, that in reality the provenance of the enigmatic taxiderm specimen residing at Marseilles Natural History Museum that is the only known representative of this very notable species was not New Zealand at all, but somewhere else entirely.

The leading researcher proffering this thought-provoking scenario is Dr Trevor H. Worthy, who has written and co-authored several scientific papers and other works relating to the lizards of New Zealand, past and present. In The Lost World of the Moa: Prehistoric Life of New Zealand (2002), co-authored with Dr Richard Holdaway, he noted that the taxiderm specimen of H. delcourti has been provenanced to New Zealand only upon the basis that the genus to which it belongs, Hoplodactylus, is known only from New Zealand, pointing out that not a single fossilised bone confirmed as being from this species has ever been discovered in the huge collections of palaeontological material obtained from South and North Islands (and despite much of this material dating from the late Pleistocene-Holocene time period).

Discovery and description of H. delcourti as documented in the now-defunct International Society of Cryptozoology's spring 1988 ISC Newsletter (© ISC/reproduction courtesy of J. Richard Greenwell)

True, two fossil items have been uncovered that were tentatively referred to H. delcourti by Bauer and Russell when they formally described and named this species in 1986, but Worthy is by no means convinced that such referrals were justified.

One of these items, found among a collection of tuatara remains, was a lower jaw comparable in size to that of tuataras but possessing spaces for teeth to be attached in sockets (the pleurodont condition, as found in lizards but not in tuataras). This had been obtained from Earnscleugh Cave in central Otago, South Island, during the 1800s, and was mentioned in passing within a paper authored by Captain F.W. Hutton that appeared in vol. 7 of the Transactions of the New Zealand Institute in 1874 (not 1875, as often erroneously claimed). Hutton speculated in a later, 1898 paper (see below) that it "may, provisionally, be supposed to belong to the extinct kumi, or ngarara, of the Maoris". Based upon Hutton's brief verbal description of its morphology and size (the former excluding the tuatara from consideration as noted above, yet the latter exceeding that of any lizard species known to exist in New Zealand today), Bauer and Russell deemed it possible that this potentially significant item was from a specimen of H. delcourti, but regrettably it has apparently since been lost, because according to Worthy it does not seem to be present in the collections of Otago or Canterbury Museums where the fossils procured from this cave are preserved. Consequently, it cannot be re-examined today.

Side view of the model of Delcourt's giant gecko featuring in the exhibition 'The Dear Departed' that was presented in 2000 by Lille Natural History Museum (© Lamiot-Wikipedia - CC BY-SA 4.0 licence)

Happily, however, the second item, also uncovered in Earnscleugh Cave and documented in vol. 31 of the Transactions of the New Zealand Institute by Hutton in 1898 (not 1899, as often erroneously claimed), does still survive, and is housed in Canterbury Museum. It consists of a small (0.55-in-long) rib-like bone that Hutton referred to as "a supposed rib of the kumi, or ngarara". Bauer and Russell interpreted it as the cloacal bone of a gecko (but without physically examining it); if so, this would make it large enough to be consistent with H. delcourti as the species from which it originated. Conversely, Worthy does not believe that other taxonomic identities for it can be eliminated from consideration, stating:

The bone is not referable to any class of vertebrates with certainty; it could be one of the several vestigial bones in a rat, duck, or tuatara, and considering that thousands of bones have been obtained from the site (Earnscleugh Cave) from these animals, but not a single other gecko bone, its referral to H. delcourti is most unlikely to be correct.

Head of the model of Delcourt's giant gecko featuring in the exhibition 'The Dear Departed' that was presented in 2000 by Lille Natural History Museum (© Lamiot-Wikipedia - CC BY-SA 4.0 licence)

More recently, in the multi-contributor volume New Zealand Lizards (2016), edited by Dr David G. Chapple, Worthy contributed a chapter entitled 'A Review of the Fossil Record of New Zealand Lizards', in which he again examined and discussed the stark absence of verified H. delcourti material, summarising this perplexing situation very succinctly as follows:

…there are now many thousands of fossil bones sampling palaeofaunas of all regions of New Zealand, including sites accumulated by predation by owls, falcons and other raptors, by pitfall into caves and which accumulated in sand dunes, swamps or lakes. The remains of many herpetofaunal species have been recovered from these sites in virtually all areas of New Zealand. Bones of tuatara are abundant and widespread. Not one bone of a gecko similar in size to a tuatara, as would be those of H. delcourti, has been found. But bones of a gecko the size of H. duvaucelii, New Zealand's largest extant gecko species, and of giant skinks, some much larger than any extant species, arc widespread. Therefore, if H. delcourti did derive from New Zealand, it must have existed in very localised habitats that have not yet been explored by palaeontologists. More likely, it was not a New Zealand animal and originates from a small island in New Caledonia, where other members of the group exist.

Dr Alain Delcourt holding the taxiderm specimen of H. delcourti that he brought to scientific attention in 1979 (Photo found on numerous websites online, e.g. here; © owner unknown to me – reproduced here on a strictly educational, non-commercial Fair Use basis only)

Worthy failed to specify, however, that there are a number of small isles lying off the two much larger, principal islands constituting New Zealand that definitely fall into his category of "very localised habitats that have not yet been explored by palaeontologists". Could it be, therefore, that the single recorded H. delcourti specimen originated from one of these smaller offshore NZ islands? To my mind, it certainly seems more parsimonious to assume that, as a Hoplodactylus species, Delcourt's giant gecko should have a provenance somewhere within New Zealand than beyond it, i.e. on an island of New Caledonia, or elsewhere.

In addition, if this species were rare or very rare anyway, the chances that fossil remains of it will even exist, let alone be discovered, will necessarily be much less likely than for more common, widely-distributed species. Also of note here is that if Worthy's assertion that H. delcourti was probably not native to New Zealand is correct, then its striking resemblance to the Maoris' mythical kawekaweau is a truly extraordinary and very formidable coincidence.

Drawing of a kawekaweau in a tree (© Hodari Nundu)

At least 150 years have passed since the type – and still the only known – specimen of H. delcourti was collected somewhere in the wild, but the many mysteries that have enshrouded it ever since still seem as impenetrable today as they did back then. Where was it collected, and by whom, is it one and the same as the mythical kawekaweau, why have no additional specimens or remains (modern-day or fossilised) ever been procured, and could there still be living specimens awaiting discovery somewhere out there?

Perhaps one day we shall have answers to some or even all of these questions. Until then, however, we have only Marseilles's long-ignored taxiderm exhibit to remind us of this most mystifying chapter in herpetological history – and just like all such exhibits, it is remaining resolutely reticent.

Rodrigues giant day gecko Phelsuma gigas, sculpture by Nick Bibby (Photo © Dr Karl Shuker)

NB – Some gecko coverages state that the world's largest modern-day gecko species was actually the now-extinct Rodrigues day gecko Phelsuma gigas, once native to the Mascarene island of Rodrigues and various tiny offshore islets but last collected in 1842. However, although its snout-tip-to-vent length could exceed that of the only known specimen of H. delcourti (14.6 in), its total length (i.e. from snout-tip to tail-tip) was less.

This ShukerNature blog article is adapted and updated from my account of Delcourt's giant gecko contained within my book The Encyclopaedia of New and Rediscovered Animals.