How Many Species of Macroscelides are there?

The Round-eared Sengi (Macroscelides proboscideus) is distributed from central Kaokoveld in north-western Namibia to the south-eastern Cape of South Africa – a linear distance of over 2000 km. Within this range the species shows extraordinary variation in pelage colour, and this has stimulated taxonomists, over the past 200 years, to describe three separate species and numerous subspecies. For example, Austin Roberts (1951), an avid “splitter”, recognised two species and nine subspecies. Corbet and Hanks (1968), which is the current authority on sengi taxonomy, recognises only one species that varies from dark individuals in South Africa to light individuals in Namibia. However, Corbet and Hanks (1968) also suggested that the subspecies M. p. flavicaudatus, with its light buff or pinkish pelage from the Northern Namib Desert and Skeleton Coast of Namibia, might be a full species.

A specimen (the dark one in the photograph) recently collected from the Gai-as area of Damaraland (northwestern Namibia) has now re-opened the can of worms: All Round-eared Sengis in this area were thought to be of the light buffy type (M. p. flavicaudatus) – as pictured alongside the dark specimen in the photograph. Dark animals are common in Namibia, but only from the Mariental area and south into South Africa. Up until now, specimens from the central Namib Desert and north have been the light buffy type, not the dark form. The dark specimen was collected about 50 km west of a place where a light one was collected, and both specimens were collected on the typical gravel substrate of the region. Thus, ecologically the two forms would appear to be sympatric in this area.

This situation can be interpreted in three ways: 1.Perhaps M. proboscideus is dimorphic and the dark individual is just a rare but natural occurrence within the normally light-coloured individuals in north-western Namibia (but this casts doubt on the clinal variation in colouration suggested by Corbet and Hanks, 1968). 2. The dark form in Namibia is a separate species, which must be rare as it has been collected in this region only once. 3. The dark form in northern Namibia represents a large range extension of the dark form found in southern Africa. The second and third interpretations are supported by the close association of light and dark forms at Gorrasis in the NamibRand Nature Reserve in the south-central Namib Desert. In either case, it suggests that the distribution of the dark and light forms in Namibia may be parallel and extend up the country on the western side of the escarpment that separates the Namib Desert and Pro-Namib from the high plateau inland.

An intriguing possibility is that the dark specimens in Namibia represent the long-lost Macroscelides melanotis, which was collected by the explorer Alexander in the early 1800’s (and described by Ogilby in 1838). The locality given for this type specimen was ‘Damaraland’ (i.e., north-western Namibia), but because it was never subsequently collected from the region and dark forms were thought to occur only in southern Africa, the locality was regarded as incorrect – and the single specimen of M. melanotis was considered the same as M. proboscideus with an incorrect collection locality (Corbet and Hanks, 1968). Maybe Alexander’s locality WAS correct, and the dark specimen in the photograph is verification that M. melanotis does exist. This raises the possibility that there are three species of Macroscelides: M. proboscideus in southern Africa (south of the Orange River?), and M. melanotis and M. flavicaudatus in Namibia, north of the Orange River.

The time is ripe for a closer examination of the taxonomy of Macroscelides, but additional collecting will need to be done before a careful analysis is possible.

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Corbet, G. B., and J. Hanks. 1968. A revision of the elephant-shrews, Family Macroscelididae. Bulletin of the British Museum (Natural History) Zoology 16:47-111.

Ogilby, W. 1838. A selection of the Mammalia procured by Captain Alexander during his recent journey into the country of the Damaras on the south west coast of Africa. Proceedings of the Zoological Society of London1838:5-6.

Roberts, A. 1951. The mammals of South Africa. Central News Agency, Cape Town.

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Mike Griffin, Namibia Ministry of Environment and Tourism, Windhoek, Namibia, and Galen Rathbun, Department of Ornithology and Mammalogy, California Academy of Sciences, San Francisco