Herp of the Day: Varanus [timorensis] auffenbergi

"Roar! I can't believe you caught me!"

Now that Halai is safe and recovered, I can post about his lovely little species. Before I begin - you definitely need to view some of these pictures large and in detail to appreciate them - blogger shrinks them all and loses detail. Just click on each picture to see it full size.

Halai is a Timor monitor, Varanus [timorensis] auffenbergi, a species of dwarf monitor from the island of Timor, north of Australia.

(Source)

The Timor monitor originally inhabited the monsoon forests of Timor before their extensive clearing, being quite arboreal. Observations have since shown it to be adapting to the deforested landscape and using rocky areas. In captivity, they seem fairly simple to keep, although shy.


This is quite a colorful little Varanus (although it is no prasinus), with pale blue ocelli, orangish coloration underneath, and bold dark-and-yellow patterning on the legs. The species' general shyness, and the fact that this guy escaped for a week and left me bloody over it, prevented me from getting great pictures of the back pattern.


The taxonomic history of this species is very unstable, which is why I leave the name with brackets: Varanus [timorensis] auffenbergi. Part of an Australian radiation of dwarf monitors in the subgenus Odatria, timorensis was originally described as a wide-ranging polytypic species from Indonesia to New Guinea and Australia. Since then, the various subspecies have been elevated to species status, leaving timorensis only on the island of Timor proper. Such elevated species include glauerti, scalaris, and tristis.


Some authors believe there is even more splitting to be done in timorensis. Color pattern is variable between the Timor mainland and the several satellite islands. Sprackland (1999) described the form on Roti island as a separate species, V. auffenbergi. This is the taxon that Halai belongs to, and is separated from timorensis by coloration only, with blue rather than grey ocelli and unmarked creamy-orange color underneath, whereas timorensis is duller with markings underneath.


I strongly contest this split, and it surprises me that it appears to generally be accepted in the years since (it is possible that this acceptance is more from the hobbyist field than the academic, I am not well read in either to know for sure). First - Sprackland describes this species on the basis of two specimens taken from the hobbyist trade, who differ from timorensis only in coloration. There are no fixed differences known between auffenbergi and timorensis in morphology and scalation, at least with a sample size of two. This renders the identification highly suspect - morphology and scalation are heavily used to diagnose reptile species (as opposed to the relatively dominant role of plumage and song in birds) and the lack of any differentiation is very odd. Kirschner (1999) noted that colors in auffenbergi can fade in captivity, rendering them nearly indistinguishable from timorensis. del Canto (2007) reported a timorensis-like monitor on a smaller island near Roti, Pulau Ndao, that was somewhat intermediate in coloration between timorensis and auffenbergi. The diagnosis of a species on something so simple as a variable color difference seems very very weak, at best.

My final disagreement with auffenbergi is the venue of description - the magazine Reptile Hobbyist. Simply put, new species descriptions belong in peer-reviewed scientific literature, not hobbyist magazines. It really makes me wonder if this paper would have even made it through peer review.

So, do we have a case of multiple cryptic species on each of the islands in the Timor complex, or is it simply a case of varying coloration within one species? I believe the splitting of auffenbergi as a species was incredibly premature, although it may well prove valid. The one thing that can be said definitively is that a thorough taxonomic revision of these monitors is needed to sort it out. Pianka and King (2004) mention such a study is in prep - I can't wait to see the results. In any case, I'll continue to recognize Halai as V. [timorensis] auffenbergi, to recognize him as the color form but likely not a separate species. I'll also continue to keep Halai in his cage, safe from making unplanned expeditions to the hidden depths of my kitchen.



References

Thanks to RG Sprackland for providing a pdf copy of his paper!

Del Canto, R. 2007. Notes on the occurence of Varanus auffenbergi on Roti Island. Biawak. 1(1): 24-25.

Eidenmuller, B. 2007. Monitor Lizards: Natural History, Captive Care, and Breeding. Edition Chimaira.

Kirschner, A. 1999. Bemerkungen zur Pilege und Zucht vom Timorwaran der Insel Roti, Indonesien. Herpetofauna 21(123): 13-18.

Pianka, ER, DR King, and RA King. 2004. Varanoid Lizards of the World. Indiana University Press. [Timorensis chapter]

Sprackland, RG. 1999. New species of monitor (Squamata: Varanidae) from Indonesia. Reptile Hobbyist. February: 20-27.