By Paul Donovan
The family Gerrhosauridae encompasses six known genera. Four of these occur in sub-Saharan Africa, and make up the subfamily Gerrhosaurinae:
- Angolosaurus (one species- Angolosaurus skoogi)
- Cordylosaurus (one species- Cordylosaurus subtessellatus)
- Gerrhosaurus (six species – Gerrhosaurus flavigularis, G. major, G. multilineatus, G. nigrolineatus, G. typicus, G. validus)
- Tetradactylus (six species- Tetradactylus africanus, T. breyeri, T. eastwoodi, T. ellenbergeri, T. seps, T. tetradactylus).
Two further genera Tracheloptychus (two species) Tracheloptychus madagascariensis, T. petersi, and Zonosaurus (18 species) Zonosaurus aeneus, Z. anelanelang, Z. bemaraha, Z. boettgeri, Z. brygooi, Z. flavescens, Z. haraldmeieri, Z. karsteni, Z. laticaudatus, Z. madagascariensis, Z. maramaintso, Z. maximus, Z. ornatus, Z. quadrilineatus, Z. rufipes, Z. subunicolor, Z. trilineatus, Z. tsingy), are restricted to Madagascar and make up the subfamily Zonosaurinae.
If you trace their ancestry back, it appears that the family almost certainly evolved as one, before Madagascar split from the African continent during the Cretaceous period, 145 to 65 million years ago. This is how the two Madagascan Genera then evolved independently. Thanks to their similarity in appearance, Gerrhosauridae was initially classified as being a subfamily of Cordylidae, but a taxonomic review some years back, meant that lizards in this group are now regarded as full species.
Once common
When I first became interested in herpetology some 40 years ago, plated lizards were well represented by quite a number of species; the species that introduced me to the family was the Giant plated lizard Gerrhosaurus validus, which you are lucky if you see nowadays. The mantle of ‘commonness’ if you will, has now been taken over by the ever popular Gerrhosaurus major; an appealing, hardy and adaptable lizard with some character. Another species that has become quite common over the years, is the Yellow-throated plated lizard Gerrhosaurus flavigularis. Again, it is a hardy species, lending itself well to the beginner as a reasonably sized, and competitively priced, lizard.
I have had the pleasure of finding both Gerrhosaurus validus while on a trip to the Limpopo region in South Africa many years ago, and nowadays live with Gerrhosaurus flavigularis literally in my backyard. When you find species that you have looked after in captivity in the wild, it almost takes you back in time, and you have this joyous feeling of “wow, I kept this species 40 odd years ago, and now I’ve found it in the wild”. Trust me, there is no better experience, than catching a snake or lizard in the wild that you have kept in captivity – even common species take on a completely new dimension.
The Yellow-throated plated lizard Gerrhosaurus flavigularis is the most common of the five Gerrhosaurus species (G. major, G. multilineatus, G. nigrolineatus, G. validus) I find here in Botswana. The others have quite a sporadic distribution in the county, with G. validus only just creeping into the North-eastern region on the Zimbabwean side. I have searched for this species in this region, and have never come up trumps, so I suspect it is at the very limit of its distribution. I do have a friend in Zimbabwe who reports them to be quite widespread throughout his country.
The individuals offered for sale in captivity are generally exported from South Africa or Kenya, as Botswana does not issue permits to export any reptile species; or even invertebrates, come to that. In fact, you can’t even get a licence to keep them as ‘pets’. I know someone who was hauled up in front of a magistrate, and fined for keeping two leopard tortoises in his garden – they had the freedom to roam, and were not caged. He was told by an officer from the Department of Wildlife “had he been keeping them to eat, that would have been ok, but he couldn’t keep them as pets”. Please tell me where the reasoning is in that!
Anyway, back to the lizard in question. Gerrhosaurus flavigularis has quite a wide distribution, occurring in the Central and eastern parts of Africa, radiating out into South Africa, Zimbabwe, Mozambique, and up the Eastern regions into Kenya and Sudan. It is quite an adaptable lizard, inhabiting just about any type of environment, from dry savannah, through to the urban garden.
As reptiles go, this is one species that has found favour with the green-fingered brigade, for they polish off many species of insect pests. They are typically burrowing lizards, excavating a burrow at the base of a tree or rock although, as is so often the case with individuals I find, are equally at home living amongst a pile of leaves or garden rubbish. They may also take up residence in disused termite mounds.
Despite all the superstitions mumbo jumbo surrounding snakes and lizards here in Botswana, this is one lizard that seems to have endeared itself to kids who take great delight in trying to catch them; which they seldom do. They are extremely agile and nimble lizards, that quickly disappear amongst the undergrowth, or wedge themselves amongst the crevices of rocks, for which no prodding or poking will get them out.
I’ve lost count of the number of times I’ve stumbled through the bush like a native whose drunk too much of the local brew, only to end up with blooded knees and a handful of painful thorns trying to catch an individual. As with so many lizard species, this one is quick to drop its tail. Very few individuals I find, are ever in full ownership of this extremity. Somewhere along the line, they have had a run-in with something or other, and dropped their tail. The tail does regenerate, but tends to be much duller in colour. In many individuals it may also remain black. When first captured, these lizards wriggle and writhe like an animal possessed, but with some gentle handling gradually calm down. This trait may also be exhibited in captive individuals, but is soon lost, and they quickly settle down to make good captive animals.
Gerrhosaurus flavigularis is a fairly robust, medium sized lizard with a typical snout to vent length of around 14cm; one could easily double that if you add on the tail – providing it has one of course. Both sexes are of similar size, with males being identified by the presence of 11-17 femoral pores that are lacking in females. It is possibly one of the more attractive members of the Gerrhosauridae, being a reddish brown on the back, with a pair of prominent black edged yellow dorso-lateral stripes running the length of the body. The sides are similar to the back, often exhibiting yellow flecks, and the belly creamy white. The Yellow-throated plated lizard bears a superficial resemblance to the Black-lined plated lizard Gerrhosaurus nigrolineatus, though the latter tends to be lighter in colour and is slightly larger. It also does not have as wide-a-distribution in Botswana.
The quickness with which this lizard shows in escaping an adversary, also plays in its favour when catching prey. It is a very nimble lizard, skilled in chasing down the quickest of prey that includes a variety of insects, ranging from fast running beetles to grasshoppers/locust, crickets, small baboon spiders, camel spiders, through to the more dawdling millipedes. Given the chance, if they enter an occupied rodent burrow they will also take pinkies and fuzzies. Juveniles contend themselves with a diet of fat juicy termites and ants, and are probably more common around termite mounds than the adults; adults tend to make use of them more for shelter and possibly egg laying, than a food larder.
Captive Care
Housing requirements are pretty basic in their needs and this is one of the reasons why they have found favour as a good first time lizard, particularly for children. In the wild both sexes live a solitary life, and while they can be kept like this in captivity, they will also fare well when maintained in small groups consisting of a male and two or three females. Do not be tempted to keep males together. Not only do they establish territories, but will fight like sumo wrestlers during the breeding season, when they become totally intolerant to one another. This can lead to stress in the submissive individual who will hide away, and be unable to compete for food, eventually wasting away.
A good amount of floor space will be required for a group as they are active lizards, so one should consider nothing less than a 4’ cage as being the absolute minimum. They are not climbing lizards, so cage height is not as important as floor area.
As they occur in quite dry regions, the substrate should reflect this. One can either use sand, bark chip, large grade vermiculite, or one of the other commercially available substrates. Some cork bark, broken plant pots, and a few branches placed on the floor will provide shelter. Freshwater should be made available at all times, although much of their water requirements will be met through the food they eat. In some regions of their range (particularly here in Botswana), they may not see rainfall for months on end.
Temperature wise, these are warmth loving lizards. In the wild, I often encounter them out and about when the sun is at its hottest during the summer months. I would suggest keeping them at a daytime temperature of 29–33C (84–91F) dropping to around 25–27C (77- 80F) at night. A good thermal gradient across the cage will enable you to determine what optimum temperature they prefer, and adjust it accordingly.
As quite shy lizards, you very rarely see them in the open basking on rocks as other lizards do. They tend to thermoregulate in warm patches of sun in small protective clearings, where they lie flat on their belly with the legs spread wide, as though mimicking an aeroplane. In captivity, a small heat lamp suspended at one end of the cage, where the temperature reaches in the mid 90’s, will provide a suitable basking spot. Lighting should be full-spectrum UVB. During the summer months a 12-hour day/night cycle should be offered, while in winter this should drop to 10/14 day/night.
Diet
Dietary requirements are simple in their needs, and you seldom encounter a problem feeder. A varied assortment of insects should be offered that have been dusted with a calcium/vitamin/mineral supplement. Some fruit and vegetable matter can also be offered once or twice a week as a supplement to the insect diet, again sprinkled with a good supplement. Pinkies will also be taken, though these should always be used in moderation, as it is easy for an individual to quickly become obese.
Breeding
During early summer, the male undergoes quite a dramatic change in colouration, signalling his coming into breeding condition. The underside of his chin, throat, as well as the chest region, turn bright red or yellow. During this time of the season, males will see-off potential rivals in the vicinity by biting and relentlessly chasing them away. I suspect this is one of the reasons why so many individuals lose their tails along the way.
Males relentlessly pursue females into mating submission. During copulation the male will often hold onto the female by the front leg, or hold her neck region in his mouth. Once mating has finished, both parties go their separate ways.
Sometime after mating, the female will begin looking for a suitable spot to lay her eggs. This is usually an excavated hole beneath a rock or fallen tree, or amongst leaf-litter, into which she will lay up to four eggs. Incubation times vary marginally, depending on the lizard’s distribution, and can extend anywhere between 90 and 120 days. When incubated artificially at 30C (86F), a typical incubation period is around 90 days. In the wild, hatching usually coincides with mid to late summer when food is in abundance. Hatchlings measure 10cm (+/-).
In some parts of their range, the lizard may experience a drop in temperature during the winter season. If you experience difficulty in breeding your lizards, it may be worth while dropping the temperature a few degrees for four to six weeks prior to the onset of summer.
Tail–End
If you are after a good sized lizard that is both adaptable, feeds well and places few challenges on you, then you can do no better than look towards the Yellow-throated plated lizard. In my experience, most of the Gerrhosaurus are hardy, and can be given the same parameters as this species in captivity.
