Dark elephant shrew

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Dark elephant shrew
Dark elephant shrew (Elephantulus fuscus) (drawing from the first description by Wilhelm Peters, 1852)

Dark elephant shrew ( Elephantulus fuscus ) (drawing from the first description by Wilhelm Peters, 1852)

Systematics
Superordinate : Afrotheria
without rank: Afroinsectiphilia
Order : Elephant jerk (Macroscelidea)
Family : Elephant jerk (Macroscelididae)
Genre : Elephant shrews ( Elephantulus )
Type : Dark elephant shrew
Scientific name
Elephantulus fuscus
( Peters , 1852)

The dark elephant shrew ( Elephantulus fuscus ) is a species from the genus of elephant shrews . It occurs in eastern Africa , but its range is limited to a small region in the Zambezi catchment area . The habitat consists mainly of open forest savannas. In its external appearance, the dark elephant shrew resembles the other representatives of the genus, like this it is characterized by a trunk-like elongated nose and long hind and short front legs. The way of life of the dark elephant shrew has hardly been researched. It was first described in 1852, but it was considered identical to the short-nosed elephant shrew until the 1970s . No information is known about the population and its possible threat.

description

Habitus

The dark elephant shrew is a small representative of the elephant shrews . It is very similar to the short-nosed elephant shrew ( Elephantulus brachyrhynchus ), its head-trunk length varies from 10.5 to 12.5 cm, its tail length from 8.6 to 11.6 cm. This makes the tail slightly shorter than the rest of the body (90%). The weight is around 45 to 46 g. Outwardly, the dark elephant shrew resembles the other species of elephant shrew with its large head and trunk-like elongated nose and short front and long hind legs. The back fur is soft and dark brown in color. The belly, on the other hand, shows a dark gray tint. The color of the tail is similar to that of the trunk, dark on top and lighter on the underside. A black streak of woolly hair sometimes runs across its center line. At the end of the tail, there is no tuft of hair made of elongated hair, as occurs in some South African species. The ears are relatively large with a length of 20 mm and the tips are rounded. The supratragus is slightly swollen and turned backwards, the characteristic is more clearly developed than in the short-nosed elephant shrew, but less pronounced than in the dark-footed elephant shrew ( Elephantulus fuscipes ), it is used as a distinguishing criterion between the three species. The eyes are large and surrounded by a whitish eye ring. Arms and legs each end in five rays with claws. The hands and feet, like the lower limb sections, are dark brown in color. The rear foot reaches a length of 28 to 30 mm, it is three times longer than the front foot.

Skull and dentition features

The length of the skull is 32.7 to 35.5 mm, the width at the zygomatic arches 17.2 to 18.4 mm. The infraorbital foramen shows a triangular outline in the front view, whereas it is oval in the side view. The dentition consists of 42 teeth along the dental formula is: . Noteworthy is the appearance of a third lower molar , albeit a small one , which does not occur in the genus except in the short-nosed and dark-footed elephant shrews. In the upper row of teeth, the inner incisor (I1) is significantly larger than the two outer (I2 and I3), the canine tooth resembles the rear molar teeth ( molar-shaped ). The length of the upper row of teeth varies from 16.3 to 17.9 mm.

Distribution area (green) of the dark elephant shrew

distribution

The dark elephant shrew is endemic to East Africa , but its range is limited to northern Mozambique in the Zambezi Valley , southern Malawi and south-eastern Zimbabwe . As a result, the species occurs mainly in the Zambezi woodland zone. The preferred habitat consists of grasslands with bushes and trees that grow mainly on sandy soils. No information is available on population density and size. The dark and short-nosed elephant shrew occur together near the Mozambican city of Tete .

Way of life

Little is known about the way of life of the dark elephant shrew. It is assumed that it corresponds roughly to the short-nosed elephant shrew and that it includes an insect- based diet.

Systematics

Internal systematics of elephants according to Heritage et al. 2020
 Macroscelididae  
  Macroscelidinae  
  Macroscelidini  


 Galegeeska


   

 Petrodromus


   

 Petrosaltator




   

 Macroscelides



  Elephantulini  

 Elephantulus



  Rhynchocyoninae  

 Rhynchocyon



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The dark elephant shrew is a separate species from the genus of elephant shrews ( Elephantulus ), which contains eight other species. The elephantulus inhabit large parts of southern and eastern Africa and constitute a part of the family of shrews (Macroscelididae) within the same order (Macroscelidea). The elephants are rather small animals that are endemic to Africa. The family today consists of two subfamilies. One of them are the Rhynchocyoninae, in which only the proboscis dogs ( Rhynchocyon ) stand and are therefore monotypical . These are mainly adapted to densely wooded habitats and represent the largest representatives of the elephant. The second subfamily is made up of the Macroscelidinae, which, in addition to the elephant shrews, also includes the trunk rat ( Petrodromus ), the North African elephant shrew ( Petrosaltator ), the Somali elephant shrew ( Galegeeska ) and the species of the genus Macroscelides . The representatives of this group have their habitat in mostly drier and more open landscapes and thus occur both in savannahs and in desert-like regions. Molecular genetic analyzes suggest that the separation of the two subfamilies took place in the Lower Oligocene around 32.8 million years ago. A greater diversification of the Macroscelidinae began in the Upper Oligocene around 28.5 million years ago.

Internal system of elephant shrews according to Smit et al. 2011
 Elephantulus  


 Elephantulus fuscus


   

 Elephantulus fuscipes



   



 Elephantulus rufescens


   

 Elephantulus brachyrhynchus



   

 Elephantulus rupestris


   

 Elephantulus intufi




   

 Elephantulus myurus


   

 Elephantulus edwardii


   

 Elephantulus pilicaudus






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The representation here neglects the positions of Petrodromus , Petrosaltator , Galegeeska and Macroscelides , all four of which are currently deeply embedded in Elephantulus , making the genus of elephant shrews paraphyletic .

Wilhelm Peters

Another result of the molecular genetic studies is that the elephant shrews currently form a paraphyletic group, since Petrosaltator , Petrodromus and Macroscelides are currently still deeply embedded in the genus Elephantulus . In addition, however, the analyzes advocate a close relatives group of some predominantly South and East African species. The position of the dark elephant shrew within the genus could only be determined uncertainly, but together with the dark-footed elephant shrew ( Elephantulus fuscipes ) it forms an allopatric group. The genetic investigations did not reveal a close relationship between the two species and the short-nosed elephant shrew ( Elephantulus brachyrhynchus ), which was originally thought to be due to the development of the third lower molar. Due to this feature, the dark and dark-footed elephant shrew were considered to be of the same species as the short-nosed elephant shrew. It was also used in 1906 to separate the genus Nasilio from Elephantulus (both genera differ from Macroscelides in their less swollen tympanic membranes ); the type of Nasilio formed the short-nosed elephant shrew. A revision of the elephant shrew in 1968 led to the association of Nasilio with Elephantulus , and the dark-footed elephant shrew was recognized as independent. The dark elephant shrew did not regain its species status until six years later, as observations have shown that it occurs sympathetically with the short-nosed elephant shrew near Tete in Mozambique . There are no known subspecies of the dark elephant shrew.

Possible fossil records of the dark elephant shrew go back to the Pliocene . The oldest finds come from Makapansgat in South Africa and are between 3 and 2.5 million years old. The important sites of Sterkfontein and Swartkrans are located in the regional vicinity of Makapansgat . There the species occurs in layers that were dated to an age of 2 to 1 million years ( Sterkfontein Member 5 East and Swartkrans Member 2 and 3 ). However, the dark elephant shrew is much less documented by finds than the dryland elephant shrew ( Elephantulus intufi ) which occurs there at the same time . Another important find site with remains of the dark elephant shrew is the Olduvai Gorge in Tanzania , whose finds are 1.87 to 0.6 million years old. All fossil remains are assigned to the extinct subspecies Elephantulus fuscus leakeyi . It is noteworthy that both find regions (South Africa and Tanzania) lie far outside the current range of the dark elephant shrew. The Olduvai Gorge is around 1200 km further north, while Makapansgat is around 500 km further south-west. The exact allocation to the dark elephant shrew is not certain, however, as the remains could possibly also represent the short-nosed elephant shrew or a representative of Elephantulus that is now extinct . Because of this, a scientific revision of the find material was recommended, on the one hand to narrow down the former distribution area more precisely, but on the other hand to clarify morphological similarities with the short-nosed elephant shrew and to exclude or confirm a possible mix-up. The short-nosed elephant shrew is now common in both Tanzania and South Africa.

The first scientific description of the dark elephant shrew was provided by Wilhelm Peters in 1852 under the name Macroscelides fuscus . Peters had traveled to large parts of southern Africa between 1842 and 1848 and observed the species near Boror, around 20 km northwest of Quelimane in northern Mozambique, the region is considered a type area. He also noted that this was much rarer than other known representatives of the elephant shrews at the time. His specimen examined for naming the species had a body length of 11.2 cm and a tail length of 9.8 cm. As early as 1851, Peters had presented M. fuscus under this name in a short report; the very detailed description was given the following year in his travelogue Scientific trip to Mossambique .

Threat and protection

Little information is available about the dark elephant shrew. It is currently not known whether there is a threat to the population and, if so, how great the potential hazard would be. For this reason and because of the very limited distribution area, the IUCN classifies the species in the category of “insufficient data basis” ( data deficient ). The dark elephant shrew is found in some nature reserves.

literature

  • GB Corbet and J. Hanks: A revision of the elephant-shrews, Family Macroscelididae. Bulletin of the British Museum (Natural History) Zoology 16, 1968, pp. 47-111
  • Stephen Heritage: Macroscelididae (Sengis). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 8: Insectivores, Sloths and Colugos. Lynx Edicions, Barcelona 2018, pp. 206-234 (p. 232) ISBN 978-84-16728-08-4
  • Mike Perrin: Elephantulus fuscus Dusky Sengi (Dusky Elephant-shrew). In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 267-268
  • Galen B. Rathbun: Elephantulus fuscus (Peters, 1852) - Peters' short-snouted elephant-shrew. In: John D. Skinner and Christian T. Chimimba (Eds.): The Mammals of the Southern African Subregion. Cambridge University Press, 2005, pp. 27-28

Individual evidence

  1. ↑ a b c d e f Mike Perrin: Elephantulus fuscus Dusky Sengi (Dusky Elephant-shrew). In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 267-268
  2. ↑ a b c d e Galen B. Rathbun: Elephantulus fuscus (Peters, 1852) - Peters' short-snouted elephant-shrew. In: John D. Skinner and Christian T. Chimimba (Eds.): The Mammals of the Southern African Subregion. Cambridge University Press, 2005, pp. 27-28
  3. ^ A b Wilhelm Peters: Scientific trip to Mossambique: carried out on the orders of His Majesty the King Friedrich Wilhelm IV in the years 1842 to 1848. Berlin, 1852, pp. 1–205 (pp. 87–90) ( [1] )
  4. ↑ a b c d Stephen Heritage: Macroscelididae (Sengis). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 8: Insectivores, Sloths and Colugos. Lynx Edicions, Barcelona 2018, pp. 206-234 (p. 232) ISBN 978-84-16728-08-4
  5. ↑ a b c G. B. Corbet and J. Hanks: A revision of the elephant-shrews, Family Macroscelididae. Bulletin of the British Museum (Natural History) Zoology 16, 1968, pp. 47-111
  6. ↑ a b Steven Heritage, Houssein Rayaleh, Djama G. Awaleh and Galen B. Rathbun: New records of a lost species and a geographic range expansion for sengis in the Horn of Africa. PeerJ 8, 2020, p. E9652, doi: 10.7717 / peerj.9652
  7. ↑ a b Hanneline Adri Smit, Bettine Jansen van Vuuren, PCM O'Brien, M. Ferguson-Smith, F. Yang and TJ Robinson: Phylogenetic relationships of elephant-shrews (Afrotheria, Macroscelididae). Journal of Zoology 284, 2011, pp. 133-143
  8. ^ Mike Perrin and Galen B. Rathbun: Order Macroscelidea - Sengis (Elephant-shrews). In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 258-260
  9. ↑ Oldfield Thomas and Harold Schwann: The Rudd exploration of South Africa. V. List of mammals obtained by Mr. Grant in the North East Transvaal. Proceedings of the Zoological Society of London 1906, pp. 575-591 ( [2] )
  10. ^ D. Margaret Avery: An assessment of the Lower Pleistocene micromammalian fauna from Swartkrans members 1-3, Gauteng, South Africa. Geobios 31 (3), 1998, pp. 393-414
  11. ^ D. Margaret Avery: Notes on the systematics of micromammals from Sterkfontein, Gauteng, South Africa. Palaeontologica Africana 36, ​​2000, pp. 83-90
  12. ^ D. Margaret Avery: The Plio-Pleistocene vegetation and climate of Sterkfontein and Swartkrans, South Africa, based on micromammals. Journal of Human Evolution 41, 2001, pp. 113-132
  13. ↑ TN Pocock: Plio-Pleistocene fossil mammalian microfauna of Southern Africa - a preliminary report including description of two new fossil muroid genera (Mammalia: Rodentia). Palaeontologia Africana 26, 1987, pp. 69-91
  14. ↑ Percy M. Butler: IV: Insectivora and Chiroptera. In: Vincent J. Maglio and HBS Cooke (Eds.): Evolution of African Mammals. Harvard University Press, 1978, pp. 56-68
  15. ↑ Patricia A. Holroyd: Past records of Elephantulus and Macroscelides: geographic and taxonomic issues. Afrotherian Conservation 7, 2009, pp. 3-7
  16. ↑ Patricia A. Holroyd: Macroscelidea. In: Lars Werdelin and William Joseph Sanders (eds.): Cenozoic Mammals of Africa. University of California Press, Berkeley, London, New York, 2010, pp. 89-98
  17. ↑ Wilhelm Peters: The same makes a communication about two new insectivors from Mossambique. Report on the negotiations of the Royal Prussian Academy of Sciences in Berlin that are suitable for publication, Berlin, 1851, pp. 467–468 ( [3] )
  18. ↑ C. Stuart, M. Perrin and C. FitzGibbon: Elephantulus fuscus. The IUCN Red List of Threatened Species. Version 2014.3. ( [4] ); last accessed on April 8, 2015

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