By far the rarest animal that I have encountered during my time in Mozambique has been the Mount Mulanje Pygmy Chameleon, Rhampholeon platyceps. A stunning little creature, it is endemic to the Mulanje massif, only being found in the southern and eastern-facing mid and high altitude evergreen forest of the massif. This includes the Ruo Gorge, where we came across the little guy (or possibly girl) above. Unfortunately its forest habitat remains only in fragmented patches and, due to its restricted range and the high threat of deforestation, it is declared Endangered by the IUCN Red List. We were lucky that this individual was crossing the path in front of us.
The Mulanje Pygmy Chameleon was first described in 1892 in a paper by A. Günther to the Zoological Society of London. The paper is titled Report on a Collection of Reptiles and Batrachians transmitted by Mr. H. H. Johnston, C.B., from Nyassaland and is available for free here. Like many papers of the day, Dr Günther was communicating the findings of others and it opens with a description of the people involved in what today might be considered equivalent to an author list:
Acting under instructions from Mr. H.H. Johnston, C.B., F.Z.S., Mr. Sclater has sent to the British museum a series of specimens of Reptiles and Batrachians collected by Mr. Alexander Whyte, F.Z.S., the naturalist attached to Mr. Johnston’s staff, in the Shire Highlands of south of Lake Nyassa, principally upon Mount Zomba and Mount Milanji.
This scientific description in a zoological journal misses out the context of this discovery. In 1982 the British Central Africa Protectorate, what is now Malawi, was only a year old. Mr. Harry H. Johnston was sent to the region by the British just three years earlier, in order to negotiate with the Portuguese to protect British interests and prevent Portuguese occupation of the area. (Later, Sir) Harry Johnston was an explorer and a politician, a fixture in the seven major European powers’ Scramble for Africa, negotiating treaties with local chiefs to establish Malawi as British territory. He later became the British Central Africa Protectorate’s first Commissioner. However, Johnston was also a naturalist and this paper demonstrates some of the work that his team did to categorise the fauna of the area.
Unfortunately, Johnston’s labelling of the location of collected species was sometimes imprecise – the specimens described in this paper are labelled as being collected in the Shire Highlands, a 7,300 km2 plateau in southern Malawi which includes Mulanje, Blantyre, some 75 km to the west, and Zomba, some 50 km to the north. The confusion caused by this poor location label probably caused later biologists to describe a sub-species for the same animal. These biologists collected specimens from the Lichenya Plateau and Ruo Gorge and seemingly saw enough differences to define two sub-species, Rhampholeon platyceps platyceps and Rhampholeon platyceps carri. Later analysis resolved this separation.
The original paper is full of descriptions of animals “new to our knowledge of the Reptilian Fauna of the Nyassa district”. The beautifully detailed sketch on plate 34 of the pygmy chameleon (labelled #1. A different species, #2, is also sketched) demonstrates the chameleons in their assumed habitat. Notice the absence of the tail, honestly described in the text as being “lost by accident”.
“pairs of very small tubercles are placed at regular distances along the vertebral line”
The distinguishing tubercles are clear in the following photo, a thin line of green-grey along its back of its greyish brown body. Head-on you can see that Dr Günther’s simple sketch of the head was just right, with the characteristic triangle shape on the head clear in the photo. The bulging black eyes are reminiscent of the compound eyes of flies.
Back on the forest floor you can appreciate the famous camouflage ability of chameleons. The Mulanje Pygmy Chameleon might not be as vibrant as some species (see the Panther Chameleon for an impressive display) but it certainly can blend in with its surroundings. Marching up the Big Ruo path on our way to Minunu Hut, I’m sure we would have never had seen it had it been in the leaf litter to the side.
Since this animal was first described in the scientific literature, the world around them has changed, and not to their benefit. The population of Malawi has risen from approximately 700,000 to 16,500,000, and is projected to rise to 45,000,000 by 2050, putting huge pressure on the land and consequently on the chameleon’s habitat. World Bank data shows that between 1990 and 2010 the population increased by 50 % (9,408,998 to 14,769,824) and, in the same time, forested area decreased by 17 %. The Mulanje massif is experiencing the full extent of the deforestation and the Ruo Gorge, where we found this particular chameleon, is one of the few remaining patches of rainforest (which also makes it a beautifully cool route up to the plateau). Another species unique to Mulanje, the Mulanje cedar tree Widdringtonia whytei, is critically endangered – a toxic combination of demand for its timber and the poor growth of infant trees when surrounded by other plants. Both these species are losing the competition for space with the surrounding human population, an imbalance that groups such as the Mount Mulanje Conservation Trust are working to address.
Recently, pygmy chameleons closely related to the Mulanje Pygmy have been described from Mozambican “sky islands” just over the border from Mulanje. These “sky islands” are, like Mulanje, isolated inselbergs of erosion-resistant rock and rise out from the planes beneath them like islands in the sky. Mt. Chiperone, Mt. Mabu, Mt. Namuli and Mt. Inago range from 50 to 200 km from Mt. Mulanje and harbour similar evergreen rainforest habitats as can be found on Mulanje. In 2014, Branch and colleagues described four newly discovered pygmy chameleon species, isolated from one another by their restriction to evergreen mountain rainforest. All within the same genus as the Mulanje Pygmy Chameleon, Rhampholeon maspictus (Mt. Mabu), Rh. nebulauctor (Mt. Chiperone), Rh. tilburyi (Mt. Namuli) and Rh. bruessoworum (Mt. Inago) are examples of allopatric speciation – speciation that occurs as populations become isolated from one another.
The speciation hypothesis could be this. These mountains were once connected as part of a large plane. They became mountain islands due to their geological composition, resisting the erosion of the surrounding planes. As the montane rainforest habitat became restricted to the remaining high lands, so too did the ancestral pygmy chameleon that once inhabited the whole area. Over time the multiple populations of this single species diverged, enough to become reproductively isolated from one another, becoming new and separate species. If this was the case, we might expect that the evolutionary relationships between chameleons inhabiting current day mountains to related to the geographical distance between them. This is indeed what was found by Branch and colleagues – chameleons on Mt. Inago appear to have diverged first (ca. 11-20 Mya), followed by those on Mt. Mulanje and Mt. Namuli (ca. 6-16 Mya), followed by chameleons from Mt. Mabu, Mt. Chiperone and Malawi Hills (Rh. chapmanorum) which appear to have diverged from each other more recently (4-9 Mya). This reflects the geographical distance between the mountains and the present of geographical boundaries (such as rivers).
The four surveyed mountains were chosen based on a Google Earth search of the area to find large (greater than 5000 ft or 1500 m) isolated mountains in Mozambique similar to Mulanje. Mount Tumbine, which rises above the town where I live, Milange, was not included. While not as big as Mts Namuli, Inago or Chiperone, it still rises over 1500 m and has patches of rainforest similar to those in the Ruo Gorge. Tumbine is close to Mulanje, just 3.5 km separates the 900 m+ parts of the mountain, but it is isolated from Mulanje by a river, the Malosa. Could Mt. Tumbine also have a resident population of pygmy chameleons and, if so, do they form a different species to the others? Only an expedition will tell…
Günther, (1892), Report on a Collection of Reptiles and Batrachians transmitted by Mr. H. H. Johnston, C.B., from Nyassaland, Proceedings of the Zoological Society of London