Animal Reference

The lizard

10 October 2013

The lizards are an artificial grouping of vertebrate animals of the Orde Squamata and there are at least 338 species in southern Africa, including the chameleons. They occur on all the continents of the world except Antarctica and have their highest diversity in the semi-desert parts of Australia and southern Africa. Lizards differ from snakes in that the two halves of the lower jaw of a lizard are fused and the upper jaw bones are firmly attached to the skull. Some lizards have greatly reduced legs or the legs have been lost totally to allow them to burrow. Most lizards also have movable eyelids while those of geckos and snakes are fused. Many lizards can shed their tails as an anti-predator strategy but the tail regenerates rapidly. Some lizards are habitat-specific or are limited to a particular substrate.

Lizards first appear as fossils that are some 195 million years old. The early lizards were air-breathing swimmers and some that lived 98 to 66 million years ago near Amman in Jordan had tails like sharks. These ancient lizards lived during a warm period on the Earth, co-existed with the early mammals and were up to 3 m long. The Waterberg with its unique geological origin forms an excellent habitat for lizards.

The chameleons are an ancient group of specialized lizards of some 160 species that originated some 100 million years ago in East Africa or Madagascar. They are specialized lizards and have characteristic skulls that usually form a bony casque with prominent crests and tubercles and no external ears. The common flap-neck chameleon Chamaeleo dilepis is common in the Waterberg and has a body length of up to 150 mm with a ridge along the spine and a large flap on the back of the head. It usually occurs in trees and eats insects which it ambushes.

The agama lizards are found in Africa, south-eastern Europe, tropical and temperate Asia, New Guinea, Australia and the Solomon Islands, with 12 species occurring in southern Africa. They are medium to large lizards with a squat body and a large head with slightly rough scales. The body is covered with small, spiny scales and tubercles, there may be a crest of enlarged, raised scales along the spine and they have distinct throat patterns. The limbs have strong, recurved claws and the diet is mainly insects. The southern tree agama Acanthocercus atricollis with its blue head, Peter‘ ground agama Agama armata and Distant‘s ground agama Agama aculeata distanti occur in the Waterberg.

The rock monitor Varanus albigularis albigularis is the second largest lizard in southern Africa and can become 80 cm long. It has a more cylindrical body than the water monitor Varanus niloticus that also occurs on Shayamanzi and can become 1.5 m long. The forked tongues are pink or bluish in the rock monitors and dark like that of a snake in a water monitor. Rock monitors are beige to greyish brown in colour and water monitors vary from almost black to dirty brown and greenish, with yellow spots and crossbars. The monitor lizards eat a variety of small vertebrates, eggs and carrion.

The bushveld lizard Heliobolus lugubris is typically brown with darker stripes. The diet includes beetles, termites, grasshoppers, scorpions, spiders and cockroaches. The ornate rough-scaled lizard Ichnotropis capensis has a body length of usually not longer than 6 cm. It has striking colours and markings with a coppery back and black stripes down the flanks onto the tail. Males can become bright yellow and the dark stripes are edged in white with some reddish brown blotches above the black stripes. It occurs in sandy areas and mostly eats termites and other smaller invertebrates. The common rough-scaled lizard Meroles squamulosa has three pale, distinct longitudinal stripes from the snout to the tail, with some brown spots. The spotted sandveld lizard Nucras intertexta has striking black and white patterns on the front half and a plain red hind part. The ornate sandveld lizard Nucras ornata with its long, red tail, Holub‘s sandveld lizard Nucras holubi, the spotted sand lizard Pedioplanis lineoocellata with its striking white and black spots and the Waterberg sand lizard Pedioplanis rubens should also occur on Shayamanzi.

At least ten types of skink occur in the Waterberg with the Limpopo dwarf burrowing skink Scelotes limpopoensis limpopoensis being rare. Some of the skinks are legless such as Percival’s legless skink Acontias percivali because they have adapted to a burrowing habit. Wahlberg’s snake-eyed skink Afroablepharus walbergii has a broad, dark brown, white-edged stripe down each side of the body, eats small invertebrates and mainly lives in leaf litter. Sundevall’s writhing skink Mochlus sundevallii sundevallii has four short legs, a muscular body, a wedge-shaped snout and writhes strongly from side to side when being held in the hand. The typical skinks include the Cape skink Trachylepis capensis, the striped skink Trachylepis capensis, the variegated skink Trachylepis variegata variegata, the variable skink Trachylepis varia and the rainbow skink Trachylepis margaritifer. The genus Trachylepis was formerly known as Mabuya.

The typical skinks are active by day and live on the ground, rocks or in trees. They can often be attracted with blobs of butter smeared on a tree trunk and shed their tails easily. The tail of a rainbow skink is particularly effective when it is shed because it is so brightly coloured. Some of these skinks lack any patterns on the body.

Only the yellow-throated plated lizard Gerrhosaurus flavigularis and the common giant plated lizard Gerrhosaurus validus validus occur in the Waterberg, with the latter occurring only there. These lizards are large and robust, can reach a body length of 28 cm, the head is covered in symmetrical scales and they have exposed ears. The yellow-throated plated lizard has two distinct yellow stripes along each side of the back, small legs and the males have bright yellow, orange, red or even blue throats during the breeding season. Giant plated lizards usually occur in rock crevices and generally have a back with a grid of small yellow and dark spots.

There are at least three species of girdled lizard that may occur on Shayamanzi and they generally have a dull colour, ranging from black to brown and brownish yellow and live mainly on rocks, under the loose bark of trees, in hollow logs or among dead leaves. They are the tropical girdled lizard Cordylus tropidosternum, the common girdled lizard Cordylus vittifer and Jones‘ girdled lizard Cordylus jonesii. The latter has less spiny scales than other girdled lizards but the head is still triangular in shape and the jaws are bulbous. The males develop bright yellow or orange on the flanks of the body, the head, throat and chin. Females may look similar to the males in the breeding season, and only two or three lizards occupy a single crevice. Crag lizards such as the northern crag lizard Pseudocordylus transvaalensis ambush their prey which consists of a wide range of invertebrates, small lizards and even leaves, flowers and berries.

There are at least two species of flat lizard in the Waterberg. Flat lizards are small to medium in size and are slim and agile. Their most noticeable characteristic is a flat body which allows them to enter narrow crevices. The limbs are held wide apart and the long, slender tail is much longer than the body. The tail is not shed often but if it is it regenerates rapidly. These lizards vary in colour from black, blue, purple, turquoise, emerald green, red, orange to yellow and in most species the male’s tail is orange, red or yellow. The Waterberg flat lizard Platysaurus minor only occurs in the Waterberg and is usually orange on the flanks, blue on the throat and has a brown back that has white speckles. The females of the dwarf flat lizard Platysaurus guttatus are brownish with three prominent white lines on the body while the males are brightly coloured.

There are at least nine species of gecko in the Waterberg but some 1130 species occur in the warmer parts of the world with 111 species in southern Africa. Geckos have small head scales and the numerous, small teeth are cylindrical. The eyes are large and are covered with a transparent skin with unmovable eyelids, while the tongue is used to clean the eyes. Geckos usually have pads under their digits which can adhere to smooth surfaces and most geckos live in trees or on rocks.

In the Waterberg, Wahlberg’s velvet gecko Homophilus wahlbergii is found in a variety of habitats where it ambushes prey. Its head is distinct in colour from the body, the large eyes have vertical pupils and it sometimes has dark blotches or stripes on the back. The common tropical house gecko Hemidactylus mabouia is common in houses and is often found near artificial light or heat sources. The body is greyish to pinkish, sometimes with black patches. The common dwarf gecko Lygodactylus capensis capensis has lines of irregular blotches along its greyish but small body and ants and termites are an important source of food.

The common geckos have flattened bodies with large turbercles. The Cape gecko Pachydactylus capensis is similar in colour and pattern to the Transvaal gecko Pachydactylus affinis being generally dirty cream, greyish brown or brown with dark and pale blotches over the head, body and tail. However, the Transvaal gecko is usually redder and has bolder patterns that sometimes form crossbars while a dark line usually runs from the snout through the eyes. Van Son‘s gecko Pachydactylus vansoni is brown with up to nine pale crossbars and a pale, vertical stripe to form a regular geometric pattern on the back.

The speckled gecko Pachydactylus punctatus is brownish-orange with small white spots but it may also be pale grey to purplish brown above with diffuse dark brown patches. Turner‘s giant gecko Chondrodactylus turneri is widespread and has large tubercles on the head. The body colour is dark brown with widely scattered white spots. The only barking gecko in the Waterberg is the common barking gecko Ptenopus garrulus garrulous which does not have pads under the toes but it has a cylindrical tail. Its colour is reddish brown mottled with irregular brown and white splotches. The pitch of the characteristic barking call is specific to the species. It lives in a burrow in firm sand and the diet consists largely of termites which are ambushed at the burrow entrance.

Three species of worm-like lizards that generally look like earthworms occur in the Waterberg. They are the reddish to pinkish Kalahari dwarf worm lizard Zygaspis quadrifrons, the rare pestle-tailed worm lizard Dalophia pistullum and the dusky worm lizard Monopeltis infuscata.

article by: Prof J du P Bothma