Bearded Leaf Chameleon
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
A short article this time – for a short animal! This is a Bearded Leaf Chameleon, Rieppeleon brevicaudatus. Its scientific name means "Rieppel's short-tailed Lion". The 'lion' part refers to the general name of chameleons, which roughly means 'small lions'. The genus name also honours the herpetologist (a scientist who studies reptiles) Olivier Rieppel. The 'bearded' part just refers to those little scales this species has on the underside of its jaw. It's not much, but it distinguishes this one from the other leaf chameleon species.
Leaf Mimics of the Undergrowth
There are only three species currently known to constitute the genus Rieppeleon. All of them are very small and mostly brown. They are found in Central to East Africa, mostly in forests. The bearded leaf chameleon occurs in mountain forests of Tanzania and Kenya. It is one of the most leaf-like of chameleons. It lacks the long, prehensile tail of the regular and dwarf chameleons of Africa, instead having a short, stumpy tail that looks like a leaf stem. Its body is flattened and leaf-like also, with a dark lengthwise stripe that mimics the central vein of a leaf. Like other chameleons, it can change colour, but doesn't have as much of a repertoire of guises as some. It can turn yellowish, greenish, orange or brownish, and also become lighter or darker, and make the pattern of spots and lines on its body stand out. It is reaches an overall length of 8 cm/3.2".
Mostly this species is very well camouflaged. It practically disappears in the leaf mould of the forest undergrowth. Lacking the grasping tail, this chameleon doesn't climb so much, spending a lot of time walking on the ground. Like other chameleons, it has eyes that swivel independently so that it can look ahead with one eye and to the rear with the other. These eyes converge when it spots its invertebrate prey, allowing it to gauge distance and depth. Like typical chameleons, it has a tongue longer than the rest of its body, which it can shoot out to catch its prey.
There are slight differences between the males and females in this species: males are more slender, have longer tails, a taller 'crest' along their backs, and a bolder pattern. As with other chameleons, it doesn't use its colour-changing ability so much to camouflage itself, but instead for showing its mood and for courting a potential mate.
The chameleon family is amazingly diverse. All but one of the hundred-plus species occur in Africa or the island of Madagascar, with the latter holding about half the total number despite being much smaller than the African continent. Genetic studies of chameleons are providing much new info on their relationships. The three chameleons of the genus Rieppeleon used to be considered to belong to the very similar pygmy chameleons of the genus Rampholeon. They're also very similar to the Madagascan leaf chameleons, Brookesia. Indeed these three groups were first all classified under Brookesia. All of them are tiny, mostly brownish, with short, non-prehensile tails. All of them occurs on the forest floor rather than high up in the trees. But now it is clear that these three groups, despite looking very similar, are not particularly closely related – instead, they're an example of convergent evolution, where not-closely-related species can look very similar because of having similar environments and lifestyles. So the three leaf- and pygmy chameleon groups likely evolved independently from more arboreal chameleon ancestors, gaining their distinctive features as a result of adapting to a mainly terrestrial life amidst the leaf litter.
Genetic studies also allow us to discover new species. In Africa, we still have new species turning up all over the place, especially in recently explored, isolated forest and mountain regions. Expeditions have already uncovered several likely new species in the genus Rampholeon; there's no reason why there might not perhaps turn up a new species or two of Rieppeleon as well. Also, further studies of the genes will likely show us that the relationships of African chameleons are more complicated than was previously supposed. Apart from the genus Rieppeleon, additional genera like Nadzikambia, Trioceros and Kinyongia have already been split from the genus of typical chameleons, Chamaeleo, having proved to constitute quite distinct genetic groups. Future studies might indeed lead to recognition of even more distinctions in this amazing family.