Somali elephant shrew
| Somali elephant shrew | ||||||||||||
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Somali elephant shrew ( Galegeeska revoili ) |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Galegeeska | ||||||||||||
| Heritage & Rayaleh , 2020 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Galegeeska revoili | ||||||||||||
| ( Huet , 1881) |
The Somali elephant shrew ( Galegeeska revoili , partly also Elephantulus revoili ), also Somali elephant shrew or Somalia elephant shrew , is a species from the monotypical genus Galegeeska . It occurs only in a limited range in northern and possibly also in eastern Somalia and Djibouti . Their external appearance is similar to that of the representatives of the elephant shrewsand is characterized by an elongated, trunk-like nose as well as long hind and short front legs. Little is known about the way of life of the Somali elephant shrew scientifically described in 1881. Information on the species comes largely from museum specimens, of which the last known specimen was collected in 1973. Almost half a century later, in 2019, living individuals could be observed for the first time. No data are currently available on the population of the species and its possible threat.
description
Habitus
The Somali elephant shrew is relatively large compared to the representatives of the elephant shrews. It is on average slightly larger than the red-brown elephant shrew ( Elephantulus rufescens ), which is very similar to it . The total length is 25.0 to 29.4 cm, of which the head-trunk length is 12.0 to 14.8 cm and the tail length is 12.1 to 16.7 cm. This makes the tail longer than the rest of the body (120%). The body weight varies from 41 to 59 g. In terms of physique, the Somali elephant shrew resembles the other representatives of the genus and, like them, has a characteristically large head with a trunk-like elongated nose and short front and long hind legs. The back fur is soft, the hair is black to gray at the base, but brown to red-brown at the top. Occasionally, longer, black-tipped hair can be found in the fur. This makes the back fur appear pale brown-gray to red-brown. Young animals, on the other hand, show a lighter coat color, which is more yellowish and less gray. The color of the fur on the sides of the body is slightly lighter, the stomach generally has a whitish tint, the hair here differs from the fur on the back by its light-colored tips. As with the red-brown elephant shrew, the tail is monochrome, but deviating from this, it is whitish and densely hairy. The hair here has a whitish colored base and brownish tips. They become longer towards the tip of the tail and form a small tuft there, which does not occur in the red-brown elephant shrew. The head has relatively large ears that reach a length of 23 to 25 mm and are tinted gray-brown. A dark spot can be seen behind the ears. The large eyes are framed by a narrow, whitish eye ring, which is interrupted on the outside by an equally dark spot. This partially extends under the ears. The nasal mirror is hairy, which is not known in any other representative of the elephant shrew except for the red-brown elephant shrew. The front and rear legs each end in five clawed rays, with the rear foot between 34 and 39 mm long.
Skull and dentition features
The length of the skull varies from 36.4 to 38.7 mm, at the zygomatic arches it is 18.6 to 21.9 mm wide. The dentition consists of 40 teeth and shows the following dental formula : . The three incisors of the upper row of teeth are each the same size, the canine tooth is very similar to the rear molar teeth ( molar-shaped ). The length of the upper row of teeth is 17.3 to 21 mm, an average of 19.2 mm.
distribution
The Somali elephant shrew only has a small distribution area in eastern Africa , which is largely limited to the north coast of Somalia , it may also occur along the east coast of Somalia up to 470 km to the south. Only in the area around Garoowe does the species occur further inland. It was first detected in 2019 in Djibouti , neighboring to the west of Somalia . Here it is known from at least four localities, which are spread around 100 km south from Forêt du Day in the north to Assamo . The latter is close to the border with Ethiopia . The region shows no natural barriers, so the Somali elephant shrew is likely also native to Ethiopia. The entire known distribution area thus spans around 106,000 km². The height distribution of the Somali elephant shrew ranges from lowlands to mountain regions around 1300 m, the highest evidence is from the Goda massif in Djibouti with 1489 m. The habitat consists of mainly open landscapes of the Somalia-Maasai bush landing zone, whereby the species prefers stony to rocky subsoil. Animals in the Assamo region live in arid, desert-like landscapes with temperatures from 21.1 to 31.6 ° C, around 200 mm of annual rainfall and existed with capers . In the Forêt du Day, on the other hand, there is a semi-desert climate, temperatures fluctuate between 16.4 and 25.9 ° C, the annual rainfall is 430 mm. The vegetation consists of acacias , olive trees and junipers . Sometimes the Somali elephant shrew is sympathetic to the red-brown elephant shrew, which, however, lives in sandy areas. Possibly the species is rather rare locally.
Way of life
Nothing is known about the way of life of the Somali elephant shrew. Almost all information about the species comes from only 39 museum specimens, the last of which were collected in 1973 in north-eastern Somalia . The only observations of live animals are currently from Djibouti . They use blocks and boulders as a place to hide; when pressed, they emit a rhythmic drumming of feet. The latter is a form of communication known as podophony , which has also been observed in numerous other elephants. Among the eight captured animals was a pregnant female with a single fetus weighing around 11 g in a uterine horn .
Systematics
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Internal systematics of elephants according to Heritage et al. 2020
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The Somali elephant shrew is an independent species from the genus Galegeeska and its only member. This in turn belongs to the family of elephants (Macroscelididae) within the order of the same name (Macroscelidea). All representatives of the order are endemic to Africa and mostly represent smaller animals. Today they can be divided into two subfamilies. One of them are the Rhynchocyoninae, which only consist of the proboscis dogs ( Rhynchocyon ) and are therefore monotypical . They include the largest members of the elephants, who mostly inhabit densely forested habitats . The second subfamily, the Macroscelidinae, in turn consists of the elephant shrews ( Elephantulus ) and the genera Petrodormus , Petrosaltator , Galegeeska and Macroscelides . The members of this group are adapted to mostly drier and more open landscapes. As a result, they occur both in savannahs and in desert-like regions. Molecular genetic analyzes showed 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 took place with the beginning of the Upper Oligocene around 28.5 million years ago. Together with Petrodromus , Petrosaltator and Macroscelides , Galegeeska forms the tribe of the Macroscelidini , while Elephantulus is part of the tribe of the Elephantulini.
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Internal system of elephant shrews according to Smit et al. 2011 (shortened) and the position of the Somali elephant shrew
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Originally the Somali elephant shrew was one of the elephant shrews. Here, the molecular genetic investigations showed that the genus is a close related group of some predominantly South and East African species, but is currently also paraphyletic due to the deep embedding of Petrosaltator , Petrodromus and Macroscelides . The exact position of the Somali elephant shrew was considered uncertain for a long time. A closer relationship to the red-brown elephant shrew ( Elephantulus rufescens ), which was assumed due to similar morphological features such as the hairy nasal mirror, the similar facial markings and the only monochrome tail, could not be confirmed by the results of the genetic analyzes. Anatomical studies of the skull suggest a relationship to the eastern cliff ( Elephantulus myurus ) as well as to the red-brown elephant shrew.
Recent genetic studies from 2020 have shown closer ties to the proboscis and North African elephant shrews, as well as to the genus Macroscelides . The separation of this family group from the elephant shrews began around 20.9 million years ago, i.e. in the Lower Miocene . The very early separation and the no longer immediate relationship with the elephant shrews prompted Steven Heritage and Houseins Rayaleh in 2020 to introduce the new generic name Galegeeska for the Somali elephant shrew . The name is made up of the Greek word γαλἑη ( gale ) for "weasel" and the Somali word gāskä or geeska for "horn" or "corner". The latter refers to the distribution of the species in the Horn of Africa . "Weasel" is often used for smaller mammals as part of the scientific name. In Somali, gal can also mean “inhabitant”, which means that Galegeeska could be translated with “weasel of the horn” as well as with “inhabitant of the horn”. Ultimately, the part of the word gale also honors Galen B. Rathbun , who had dealt intensively with the elephants until his death in 2019. Heritage and Rayaleh highlighted the hairy nasal mirror , the tuft of the tail, the light eye ring with black spot and the equally large upper incisors as special features of the genus .
There are no known subspecies of the Somali elephant shrew. However, individuals from the southern range around Gabadir in Somalia show a paler back coloration than those further north, which is caused by hair with lighter bases and less hair with black tips. Something similar is reported from Djibouti, where animals around Assamo are more reddish-brown in color. Some of these variations are due to clinical adaptation to the subsurface. So far no fossil finds are available for the species.
The first scientific description of the species took place in 1881 by the French zoologist Joseph Huet . He used the scientific name Macroscelides revoilii . As a basis he had a 16 cm long individual that the French Africa explorer Georges Révoil had picked up near Medjourtine in what was then Somaliland (northeastern Somalia). The area is also considered a type region. The species name revoili was chosen by Huet in honor of the explorer. Until it was rediscovered in 2019, almost all information on the Somali elephant shrew was based on a 1968 revision of the elephant shrew by Gordon Barclay Corbet and John Hanks . In doing so, the two authors analyzed 15 museum specimens of the species. Individual expeditions to the region subsequently carried out were unable to provide any evidence of the animals. However, a report from 1974 noted the occurrence of the Somali elephant shrew in Djibouti, but without giving any information about the exact location. Research at the Zoological Museum of the University of Florence also led to the identification of around a dozen individuals of the species.
Threat and protection
Almost nothing is known about the Somali elephant shrew. This applies to both the exact distribution limits and the preferred habitat . For the latter, a similar landscape to that of the red-brown elephant shrew is assumed, but possibly under a drier climate influence. Due to the lack of information, the type is listed by the IUCN under "insufficient data basis" ( data deficient ). Due to the rarity of the Somali elephant shrew, the Global Wildlife Conservation designated it as one of the 25 most important taxa in their initiative to search for lost species.
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. 231) ISBN 978-84-16728-08-4
- 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
- Mike Perrin: Elephantulus revoili Somali Sengi (Somali 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. 271-272
Individual evidence
- ↑ a b c d e Mike Perrin: Elephantulus revoili Somali Sengi (Somali 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. 271-272
- ↑ a b c d e f 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
- ↑ 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. 231) ISBN 978-84-16728-08-4
- ↑ a b c d e f g h i 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
- ^ A b Galen B. Rathbun, Paolo Agnelli and Gianna Innocenti: Distribution of sengis in the Horn of Africa. Afrotherian Conservation 10, 2014, pp. 2-4
- ↑ a b c 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
- ^ 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
- ↑ Fabiana Panchetti, Massimiliano Scalici, Giuseppe Maria Carpaneto and Giancarlo Gibertini: Shape and size variations in the cranium of elephant-shrews: a morphometric contribution to a phylogenetic debate. Zoomorphology 127, 2008, pp. 69-82
- ↑ Massimiliano Scalici and Fabiana Panchetti: Morphological cranial diversity contributes to phylogeny in soft-furred sengis (Afrotheria, Macroscelidea). Zoology 114, 2011, pp. 85-94
- ↑ Joseph Hüet: Description d'une nouvelle espèce de Macroscelide. Bulletin de la Société philomathique de Paris 7 (5), 1881, pp. 95-100 ( [1] )
- ^ Galen B. Rathbun: Eponyms in the Afrotheria: Who were the people that had Afrotheria species named after them? Afrotherian Conservation 9, 2012, pp. 5-6
- ↑ Malcolm J. Pearch, PJJ Bates and C. Magin: A review of the small mammal fauna of Djibouti and the results of a recent survey. Mammalia 65 (3), 2001, pp. 387-410
- ↑ C. FitzGibbon, M. Perrin and C. Stuart: Elephantulus revoili. The IUCN Red List of Threatened Species. Version 2014.3. ( [2] ); last accessed on April 8, 2015
- ↑ Global Wildlife Conservation: 25 Most Wanted Lost Species. ( [3] ), last accessed on August 20, 2020
Web links
- Elephantulus revoilii inthe IUCN Red List of Threatened Species 2014.3. Listed by: FitzGibbon, Perrin & Stuart, 2008. Retrieved April 8, 2015.
- Christiane Gelitz: Elephant shrew rediscovered in East Africa. ( [4] ), on: Spektrum.de from August 20, 2020