Well done everyone who had a go at identifying the lizards from yesterday. Dead easy, as both species are highly distinctive and easy to identify (and both were previously mentioned in the Tropiquaria article)…
The armour-plated lizard shown with and without the effects of the flash was a Sudan plated lizard Gerrhosaurus major, also called the Rough-scaled plated lizard or Great plated lizard. It lives up to the last name, reaching 48 cm in total length. Plated lizards eat arthropods and molluscs, with the larger species (like G. major) eating smaller lizards as well as some plant material. Some plated lizards (like the Yellow-throated plated lizard G. flavigularis) have adapted well to urban areas and can be quite common there. Plated lizards are part of Gerrhosauridae, and we looked at them briefly in the recent article on the closely related girdled lizards, or cordylids. We’ll come back to them at some stage as – like Cordylus among the cordylids – one gerrhosaurid genus (Tetradactylus) is particularly interesting in exhibiting limb reduction, with the species differing in how reduced their limbs are.
The monitor was of course the unmistakeable Rough-necked monitor Varanus rudicollis (shown above): an arboreal, very dark, species from peninsular SE Asia, Sumatra, Borneo and also the Philippines (Kirschner et al. 1996). Its long, slender head and slit-shaped nostrils located close to the eye are distinctive (quite a few varanids have their nostrils located away from the tip of the snout), and of course it also has large, keeled scales arranged in 10-12 longitudinal rows on its neck. V. rudicollis has sometimes been considered distinct enough to get its own ‘subgenus’: Dendrovaranus Mertens, 1942 (e.g. King & King 1975), but it has also been included within the same ‘subgenus’ as the Yellow monitor V. flavescens, Empagusia Gray, 1838. I note that Wolfgang Böhme has suggested that, if Empagusia proves to be a distinct genus relative to Varanus, then ‘(some of) the Mertensian subgenera could perhaps (be) reinstated as such’. The monophyly of a clade that more or less corresponds with Empagusia was supported by Pianka (1995), who found the Rough-necked monitor to be closest to V. salvator, the Water monitor [shown below]. Rough-necked monitors eat a lot of insects, but they’ve also been recorded to eat crabs, frogs, mammals, birds and even fish. In parts of their range they’re imagined by the local people to spit poison.
I must do some proper articles on varanids some time: for previous contributions see the Komodo dragon article, and the ver 1 article on play behaviour in reptiles. Huh, I was going to post a pretty picture of some porcupines. Tomorrow.
Refs – –
King, M. & King, D. 1975. Chromosomal evolution in the lizard genus Varanus (Reptilia). Australian Journal of Biological Science 28, 89-108.
Kirschner, A., M üller, T. & Seufer, H. 1996. Faszination Warane. Kirschner & Seufer Verlag, Keltern-Weiler.
Pianka, E. R. 1995. Evolution of body size: varanid lizards as a model system. American Naturalist 146, 398-414.