Expedition 2008 - Tanzania / The Journal

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INTRO

The 2008 edition of the Exo Terra expedition headed for the Eastern Arc Mountains and the Southern Highlands of the Republic of Tanzania in East Africa. The main goal of this expedition was to map the amphibian and reptile biodiversity of these regions and to get a better understanding of the species inhabiting these complex eco systems.

Some of the animals you are about to see were documented and filmed for the first time in their natural habitat. These images contribute enormously to the scientific community, but are also extremely valuable for those herpetologists observing, keeping and breeding these species in terrariums.

FROM DAR ES SALAAM TO KIMBOZA FOREST

The expedition team left Dar Es Salaam, Tanzania’s biggest city, where the team had a chance to stock supplies for a journey through the dense jungles, wide-open plains and over remote mountain ridges. The first stop was Kimboza Forest, near the Uluguru Mountains. These mountains in eastern Tanzania are one of the most important mountain ranges in Africa for the conservation of biological diversity.

Kimboza Forest is one of the oldest forests in Africa and because the ecosystem has remained undisturbed by climatic and geographical changes for an estimated 25 million years, the expectations were high. The forest is also home to one of the most striking geckos ever seen; Lygodactylus williamsi.

One of the first reptiles the team encountered was a foraging Nile Monitor in the middle of the dirt road leading to Kimboza Forest. The Nile monitor, Varanus niloticus, is one of the largest members of the monitor lizard family. These usually highly aquatic animals also possess sharp claws used for climbing, digging, defense or tearing at their prey. Nile monitors are carnivores and feed on anything, from frogs to small mammals, and from crocodile eggs to carrion.

The camp was set up just outside a village at the edge of Kimboza Forest. The Flat-headed Gecko, Hemidactylus platycephalus seems to be very abundant in this area. This nocturnal gecko is found basking in the late afternoon sun on huts and trees. Like all geckos, Hemidactylus platycephalus are opportunistic feeders and feed almost on anything passing their path which fits in their mouths. Even this large spider was eventually swallowed…

Many species of reptile and amphibian are active only at night and hide during daytime. The team head out after sunset in order to observe the nocturnal herpetofauna in Kimboza forest. The first creature the team spots in a tangle of twigs is the highly venomous Eastern Twig Snake, Thelotornis capensis mossambicanus. The Twig Snake is one of the several back-fanged colubrids whose bite is highly venomous and potentially fatal. The Twig Snake's venom is haemotoxic, but its effects are very slow to take effect and bites are rare. No antivenom has been developed. The renowned German herpetologist Robert Mertens died after been bitten by an Eastern Twig Snake he kept in captivity. Usually preying on lizards, frogs and sometimes birds, Twig Snakes conceal themselves in trees, but often at a low enough levels to be able to also strike at terrestrial prey. The Black File Snake, Mehelya nyassae, is a strictly ground-dwelling snake that feeds on lizards and frogs. Although fairly common in some areas, File Snakes are very secretive and seldom seen. When threatened these snakes move in a jerky manner and excrete a foul-smelling substance from glands in the tail region.

THE CHAMELEONS OF THE KIMBOZA FOREST REGION

Although diurnal, Chameleons are sometimes easier to find whilst they are sleeping at night. When night falls, Chameleons become much paler then the surroundings which makes it easier to locate them. Chameleons usually move to the very end of twigs and branches in order to keep clear of the foraging area used by predators like snakes. Most species will drop themselves immediately upon sensing the vibrations and movements caused by a predator on the twig or branch.

This rare Sharp-nosed chameleon, Kinyongia oxyrhina, is found sleeping on a tiny twig. The Bearded Pigmy Chameleon, Rieppeleon brevicaudatus, can easily be found during nighttime because of its very specific preferred sleeping area. These Pigmy Chameleons, also called Leaf Chameleons, spend the night on leaves and twigs between 50 cm to a one meter above the forest floor, often near clearings, paths and streams. A longer tail and a more prominent dorsal crest distinguish the males of the Pigmy Chameleon. Rieppeleon brevicaudatus is capable of compressing its body laterally and producing a stripe down its side, mimicking a dead leaf.

It is only during the day that these Pigmy Chameleons really show their skills in mimicking foliage movements while walking. The distinctive jerky movements, and the animal’s shape and colour pattern mean that predators and prey alike easily overlook these remarkable animals. This male shows how its body is kept in position relative to the twig while hesitating to move forward and increasing the chance to be seen.

Another camouflaging skill is demonstrated by this juvenile Kinyongia oxyrhina as the animal flattens its body laterally and almost disappears entirely behind this thin twig. Its body is so extremely flattened that very few body parts stick out on either side of the twig. The animal also keeps its body as close as possible to the branch to avoid detection. Note the subtle but obvious changes in colour in this sped up two-minute sequence.

The Flap-neck Chameleon, Chamaeleo dilepis, is one of the most wide spread chameleon species in Africa. These striking animals are found throughout Southern and Central Africa where they typically inhabit forest edges, bush land and savannahs. The animals found here lack tarsal spurs, which might indicate that these animals are in fact Chameleo roperi, a species normally occurring more to the north. The Chamaeleo dilepis-complex possesses flap-like structures extending from the head casque, hence the name “Flap-necked Chameleon”. Moving these flaps forward is part of the threat posture of Chamaeleo dilepis, in addition to opening the mouth, laterally flattening the body and expanding the throat. Like all Chameleons, Flap-necked chameleons are well known for their ability to change colors.

They range from dull browns and blacks to vivid greens, whites and yellow. Chameleons have chromatophores in their outer skin that are controlled by the brain. As a result, they are able to consciously change coloration to adapt to their environment as well based on mood or even after assessment of a situation. Depending on the type of predator it faces, a Chameleon will change color to more specifically match its environment. When it encounters a bird there will be a better effort to match the environment than when a snake crosses its path because snakes do not see as well as birds do.

When male Chameleons fight one another to assert dominance, their colours indicate their mood. They will display bright, conspicuous colours to either frighten a competitor or to attract a female. The ability to change colour also facilitates thermoregulation. If the animal is a darker it will absorb the heat from the sun more quickly and will, therefore, need to spend less time basking. This more efficient gain of heat energy means the chameleon can spend more of its time hiding from predators or hunting for food. Conversely, if the environment is too hot and the Chameleon is unable to move to the shade quickly it will lighten its skin pigmentation in order to reflect the sun’s rays. This will keep the animal cooler than if it were to retain its regular darker pigmentation. This technique is also used to regulate the UV exposure.

IN SEARCH OF LYGODACTYLUS WILLIAMSI

Kimboza Forest is the Terra Typica, and the so far only known locality, where Williams' Dwarf Gecko, Lygodactylus wiliamsi, occurs. In order to find this almost electric blue-coloured lizard, the team penetrated deep into the forest. Within dense forests, most day gecko species live on plants or trees with smooth surfaces like palms, bamboo or Pandanus species. It is this type of vegetation that was targeted first, and with immediate success…

The first bright blue male was spotted on a large Pandanus rabaiensis and once the preferred vegetation was determined it was fairly easy to locate the geckos. Lygodactylus williamsi is only found in the 2 - 5m shrub layer of the forest on Pandanus rabaiensis. The Pandanus palms are confined to certain areas and form patches within the forest. Lygodactylus williamsi is relatively common within its very limited range.

The geckos are very territorial, with one male, one to three females, and a small number of juveniles resident on each Pandanus palm. The geckos emerge from the heart of the Pandanus in the early morning and retreat during the hottest part of the day to emerge again later in the afternoon. Lygodactylus williamsi feeds on ants, spiders and flies. The males of Lygodactylus williamsi reach a total length of about 8 cm, whilst the females are slightly smaller.

Males are bright blue with a black throat and a yellow-orange belly. The females are greenish with a copperish shade and have very little black on the throat, just a few stripes or v-shaped markings. Normally there is a clear sexual dichromatism, but semi-adult males can easily be confused with females. Lygodactylus williamsi, like chameleons, change colour when threatened: the males from bright turquoise to almost black, and the females from green to brown. This species is without doubt the most spectacular member of its genus.

Another member of the genus was found at the edge on the other side of the forest, facing the Uluguru Mountains. Lygodactylus grotei seems to prefer Coconut Palms at the edge of the forest. Each palm houses one male with several females and juveniles. The relatively common and widespread Lygodactylus luteopicturatus lives near human settlements and can also be found around the campsite. The Montane rock agama is another species that lives in these higher forest regions.

FROM KIMBOZA FOREST TO MIKUMI

The next research area was Mikumi National Park. This park abuts the northern border of Africa's biggest game reserve - the Selous – and is transected by the surfaced road between Dar Es Salaam and Iringa. It is, thus, the most accessible part of a 75,000 square kilometer (47,000 square mile) tract of wilderness that stretches east almost as far as the Indian Ocean.

The open horizons and abundant wildlife of the Mkata Floodplain, the centerpiece of Mikumi, can be compared with the plains of the Serengetti. The mammal fauna consists of impala, zebra, wildebeest and buffalo herds that migrate across the floodplains. This wildlife rich region is the hunting ground of many lion prides. Elephants and giraffes forage in the isolated acacia and baobab stands, which also provide islets of shade.

During the dry season the wildlife concentrates around Mikumi’s waterholes, which are inhabited by hippos and crocodiles. The vegetation consists of savannah grass lands, dotted with acacia, baobab, tamarinds, and some rare palms. Very little is known about the occurring reptiles and amphibians since the main focus for most researchers is mammals and birds.

The Exo Terra team was mainly interested in the geckos that live in isolated acacia and baobab trees, a habitat difficult to research because of the abundance of elephant, buffalo and lion. It appears that almost every acacia tree in the floodplain is inhabited by the Dwarf Yellow-headed gecko, Lygodactylus luteopicturates. Males have a yellow head, hence their common name, and a grayish blue body, whilst females are less conspicuously coloured. Closer observation of these geckos revealed a very interesting case of Trophobiosis which is a symbiotic association between organisms where food is obtained or provided.

Many geckos are found near or right below giant scale insects. These insects are known to produce honeydew, a sugar-rich sticky substance, secreted as they feed on plant sap. Honeydew is particularly common as a secretion in scale insects, cicadas, leafhoppers, planthoppers and treehoppers and is often the basis for trophobiosis. After digestion of the ingested plant sap in the scale insect’s gut, the residue is voided as honeydew. Many insects, including ants, flies and butterflies, as well as nectarivorous birds, consume honeydew that has fallen onto plants or other surfaces, but some animals take honeydew droplets directly from the insects. This behaviour, called tending, is widely displayed among ants.

During the Exo Terra Expedition in Madagascar the world’s first footage of this remarkable behaviour was shot; Phelsuma klemmeri tending a planthoppers’s nymph while several ants patiently wait their turns. Phelsuma vanheygeni and some lygodactylus species were also found tending a variety of plant and treehoppers. It is believed that the tending geckos gain food and the tended plant sap-feeding insect is protected from natural enemies by the geckos and ants. This is the first case of trophobiosis documented between reptiles and insects on the African mainland. The fact that reptiles usually prey on insects makes this behaviour even more unusual.

As the night falls over the savannah and the lions seem to get some extra rest for the upcoming night, the Exo Terra team starts preparing to leave early the next morning for the Poroto Mountains.

THE POROTO MOUNTAINS

The Poroto Mountains are located in South Western part of the country, near lake Malawi. The mountains can be reached by Tanzania’s major road to Mbeya Town and from here south towards Lake Malawi. The Exo Terra team stopped briefly in Iringa to stock up on food and water for the upcoming days in the rainforests. The 4x4 vehicles made it relatively easy to get all the heavy equipment to the base camp deep inside the forest. The millions of tsetse flies were the first to welcome the team during the set-up of the base camp in an open area of the forest.

Over the next few days, the surrounding forest will be systematically searched for the various endemic species of chameleon occurring in these mountain forests. The first species that found was the Flapjack chameleon or Chamaeleo fuelleborni. Its range is restricted to the rainforests of the Poroto Mountains but it is very similar to Chamaeleo jacksonii from Mount Meru, and Chamaeleo werneri from the Usambara and Udzungwa mountains. The scales on the head of Chamaeleo fuelleborni appear to be much rougher and the total length of this chameleon is somewhat smaller and reaches a length of only 20 cm.

Male Chamaeleo fuelleborni exhibit 3 well-developed, annulated horns that are also smaller than those of Chamaeleo jacksonii and Chamaeleo werneri. Females possess 3 very small annulated horns, with the central horn on the nose being somewhat larger. Males are territorial and use their horns to defeat opponents.

This is Chameleo johnstoni from the Ruwenzori in Uganda exhibiting this behaviour. Like many higher altitude species Chamaeleo fuelleborni is ovoviviparous, meaning that the eggs develop inside the female and hatch upon exit. Four to fifteen live young are born in a single clutch per year. Chamaeleo fuelleborni is easily spotted at night while sleeping on the very end of twigs and branches to detect and avoid foraging predators like snakes. Chamaeleo incornutus is a small to medium sized chameleon, growing to less than 20 cm. This species inhabits bushes in montane rainforests of the Ukinge, Ubena, Rungwe and also the Poroto Mountain ranges of Tanzania.

Large occipital lobes are present as well as a low dorsal crest, composed of relatively widely spaced, highly modified conical scales. Chamaeleo incornutus can easily be distinguished form Chamaeleo fuelleborni by the lack of horns in both sexes. The lack of occipital lobes and the finer scales sets the sympatric Chamaeleo goetzi apart from this southern highland species.

On the edge of the impressive Ngozi Crater, the rare Pitless Pygmy Chameleon, Rhampholeon nchisiensis is found. Resembling a dead leaf, colouration is usually shades of brown or grey with two to three thin dark stripes along the flank. The eye sockets often contain some blue scales, which differentiate this pigmy chameleon from most other species. Like Rieppeleon brevicaudatus, these pigmy chameleons forage and sleep on twigs and braches between 50 cm to one meter above the forest floor. This species can turn their eye sockets a shade of blue, which really makes them a stunning Pygmy Chameleon to own. The tail of Rhampholeon nchisiensis is short and stumpy, females having the shortest. Adult Pitless Pygmy Chameleons reach a total length of up to 6 cm.

The Exo Terra expeditions have revealed two completely new reptile species so far. During the Expedition to Madagascar in 2004 Phelsuma vanheygeni was discovered and during the expedition to Gabon in 2007 another new day gecko species of the genus Lygodactylus was discovered.

The Exo Terra team now has now been able to find a totally new chameleon species of the genus Kinyongia. This new species appears to be related to Kinyongia oxyrhinum from the Ulunguru and Udzungwa mountains, and to Kinyongia tenue from the Usambara Mountains. It is distinguished from Kinyongia oxyrhinum by the smaller rostral horn, the higher casque and by the larger scales on the head. The main difference with Kinyongia tenue is the overall length and the size of the casque, which is much higher in Kinyongia oxyrhinum. The single specimen was found in lower bushes about 1 m above the the forest floor. So far this chameleon species is only known from this single specimen and it is currently being described. It seems to be even rarer then Kinyongia oxyrhinum, of which only twelve specimens have been found to date.

One of the frogs to emerge soon after the first rains of the season is the big eyed tree frog, Leptopelis vermiculatus. These frogs inhabit the closed-canopy wet tropical rainforests between the altitudes of 900 and 1800 m. Leptopelis vermiculatus grows up to 85 mm and comes in two distinct colour phases, one bright green with small black specks on the dorsum and the second brown with a dark pattern. The animals in the Poroto Mountains are brownish but have some green patches and are an intermediate between the two phases. The eyes are very big compared to the body size and are golden with brown lines and flecks. The large toe pads are used for climbing and clinging on to leaves after long distance jumps.

TO LAKE MALAWI AND BACK AGAIN

In the early morning the vehicles were loaded again to move on to Lake Malawi in an attempt to find chameleons and day geckos. The road towards the lake is very challenging and very little wildlife is present here. The natural habitat in this area is completely disturbed, the only vegetation being crops and fruit bearing trees in the many gardens along the tricky dirt road.

The lake itself is astonishing, with the mighty Livingstone Mountains rising in the backdrop. It is the third largest in Africa, 550 kilometers in length and 75 kilometers wide with some parts as deep as 700 meters. The lake is biologically incredibly diverse, containing approximately 30% of world's cichlid species - the ideal spot for the Exo Terra team to get some tasty catfish to extend the limited menu.

On the way back some samples were taken in the Kiwira River without success, but in the scarce trees on the riverbank a dull grey gecko is spotted. It is Lygodactylus capensis, probably the most widespread species within the genus. This day gecko occurs in eastern and southern Africa from just below equator to the northern Cape Province in South Africa.

The green vegetation and fertile fields give way rapidly to dry grass land and savannah once you pass the town of Mbeya. The road back to Iringa Town is highly populated and not worth exploring. Savannah areas usually do not boast as much reptile and amphibian life as humid forest areas, but one of the drier areas the team definitely wanted to research is Ruaha National Park. This is Tanzania's 2nd largest national park but is second to none in species diversity due to its unique location. Most of the national park is located on the top of a 900 meter plateau whose ripples of hills, valleys, and plains makes this area uniquely beautifully.

Ruaha protects a vast tract of the rugged, semi-arid bush country that characterizes central Tanzania. The park’s lifeblood is the Great Ruaha River, which courses along the eastern boundary in a flooded torrent during the height of the rains, but dwindling thereafter to a scattering of precious pools surrounded by sand and rock. Most of the animals can be found in or near these pools during the dry season, concentrating the fauna in the park even more.

Impala, kudu, waterbuck and other antelopes risk their life for a sip of life-sustaining water. The risk is considerable since it is likely to encounter one of the over twenty prides of lion that lord over the savannah. In a relatively small area along the Great Ruaha River and its seasonal tributaries, the team stumbled upon at least three lion prides, either resting or defending their fresh kills. This female Agama, lionotus dodomae, has nothing to fear, she is simply too small. Next to the lions, the huge populations of elephant make it extremely difficult and dangerous to explore the low bushes and thickets.

The team mainly hopes to find Chamaeleo dilepis in this area, to get a better understanding of the differences between the species and subspecies within the complex. The subspecies that occurs in this area is Chameleo dilepis dilepis. Chameleo dilepis dilepis is generally the largest of the “dilepis”-complex and the males have clearly developed tarsal spurs. The base coloration of the members of this complex is green but they can have many more colors, including yellow, black, orange, white and brown. All species of the “dilepis” complex have a lateral stripe, which is generally colored white. This stripe extends from the back of the head to the end of the body. There is a high likelihood of further taxonomical revision of the “dilepis”-complex. Some of the actual subspecies are likely to gain full species status and some others will become synonyms of what is now considered Chamaeleo dilepis dilepis.

The rainbow skink, Trachylepis margaritifera, lives on the rocky outcrops along the Ruaha River. Males are very territorial and bask in prominent positions displaying their beautiful colours. Females can easily be confused with Trachylepis quinquetainiata since they have similar colour patterns.

Other frequent guests that are encountered on the rocks along the riverbed are the Agama lionotus dodomae. The males are extremely colourful and certainly the most visible lizard in the area. It is obviously the height of the mating season since the animals are showing their most striking colours. The males are extremely territorial during this time. The females are less conspicuously coloured, but are found in larger numbers then males.

A seldom seen species in the area is the leopard tortoise, Psammobates pardalis pardalis. These animals hide during the heat of the day in thickets or under shady trees.

It can be extremely hot during the day in Ruaha and many animals seek refuse in the shade of larger trees or stay around the remaining pools of the Ruaha River. Except for elephants, hippos and crocodiles are the only creatures that enter the water to avoid the extreme heat. Even during these extreme temperatures animals come and go to seek some refreshing water in what remains of the river.

The next research area is cooler and certainly more humid as this habitat is located high in the Udzungwa Mountains. Udzungwa is the largest and most biodiverse of a chain of large forest-swathed mountains that rise majestically from the flat coastal scrub of eastern Tanzania. Known collectively as the Eastern Arc Mountains, this archipelago of isolated massifs has also been dubbed the African Galapagos due to its treasure-trove of endemic plants and animals. Udzungwa alone among the ancient ranges of the Eastern Arc has been accorded national park status. It is also unique within Tanzania in that its closed-canopy forest spans altitudes of 250 metres to above 2,000 metres without interruption. The eastern Arc Mountains are small and fragmented mountains, each block having a patch of remaining dense tropical rain forests with high rainfall which form lush islands in a sea of arid savannah vegetation. The climb to the base camp from the parks headquarters is steep and gets more humid during the ascent. It takes about a day to reach the camp and upon arrival a much-needed meal was prepared for the entire team in the makeshift field kitchen.

The emphasis in these mountains lies again on chameleons and geckos, but many other creatures like millipedes, scorpions, beetles and butterflies are spotted during the search. The first chameleon found is the Bearded Pigmy Chameleon or Rieppeleon brevicaudatus. Although many striped morphs are found, it appears to be the same species as found near the Uluguru Mountains, in Kimboza Forest.

Chamaeleo deremensis, the Usambara three-horned chameleon, is without doubt one of the rarest of the large chameleons. It usually is found in other mountain ranges of the Eastern Arc Mountains, the Usamabaras and Ulugurus, but this is the first record from the Udzungwa Mountains. Here the species occurs in the vicinity of Saje Waterfall at altitudes between 300 and 700 meters. Chamaeleo deremensis is one of the more evolutionarily advanced chameleons due to its complex lung structure. They are a stocky species and have a short tail relative to the snout-to-vent length and a high dorsal crest. The casque is smooth, flattened and oblong and ends in a point bearing small, unfused occipital lobes. The Body coloration for adults is medium to pale green, with three or four pale yellow slashes that run in a broken line from behind the eye to midway down the body. A scattering of off-white, blue, red or brown patches and streaks are sometimes present. When excited or stressed, dark green or black dots appear and the colours brighten. Hatchlings and young juveniles display the same patterns as adults but on an aqua-blue background.

The males of Chamaeleo deremensis possess three large annulated horns that are somewhat smaller relative to the chameleon’s size compared to other three-horned species such as Chameleo werneri. Chamaeleo deremensis can also be distinguished from Chameleo werneri, which occurs in the higher regions of the Udzungwa Mountains, by its larger body size and the high dorsal crest. Female Chameleo deremensis lack all trace of horns, even the horn bud scales as seen in other three-horned chameleons are not even present. Both sexes display the same colouration and are comparable in size when mature.

The team were still determined to find other chameleon species and spent several days above Saje Waterfall at an altitude of about seven hundred meters. Several searches for Chamaeleo werneri at higher altitudes were without success.

The expedition was near the end and the Exo Terra team still had to descend to the road that would bring them back to Mikumi and further to Dar Es Salaam. The descent is an incredibly beautiful hike with spectacular views on the waterfall. It was on top of this waterfall the team had camped for several days.

Just before arrival in the village, a Bell’s hingeback tortoise was found crossing the path. The genus Kinixys is unique in the tortoise world in having a hinged carapace. This hinge enables the tortoise to close down the rear of its shell to protect itself from predators.

The Exo Terra team can look back at a very successful expedition, with again for the third time, the discovery of a new species. Many animals in this movie were filmed in their natural habitat for the first time, revealing a unique insight into their ecology and behaviour. The expedition will surely contribute to a better understanding of Tanzania’s remarkable and spectacular herpetofauna.

 
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3rd discovery of a new species during Exo Terra expedition