Etendeka short-eared elephant
| Etendeka short-eared elephant | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Etendeka short-eared elephant ( Macroscelides micus ) |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Macroscelides micus | ||||||||||||
| Dumbacher , Rathbun , Osborne , Griffin & Eiseb , 2014 |
The Etendeka macroscelides proboscideus ( macroscelides micus ), also Etendeka round ear elephant shrew called, is a mammal species in the genus Macroscelides that in the family of shrews part (Macroscelididae). The species is the smallest member of the elephant family so far. It is endemic to northwestern Namibia and inhabits barren, scree-rich landscapes at medium altitudes. It was only discovered in 2006, the first scientific description took place in 2014. Overall, the Etendeka short-eared elephant is only known from around three dozen specimens. There is hardly any data about the way of life, the animals are strictly nocturnal, use comparatively large action areas and spend the daytime heat under boulders. The stock is not considered to be threatened.
description
The Etendeka short-eared trumpet is the smallest member of the trumpet and reaches a total length of 17.0 to 19.5 cm, of which 8.3 to 9.7 cm is on the tail. The weight varies between 22.3 and 31.3 g. Like all representatives of the genus Macroscelides , it is characterized by a round body, a round head, long and slender limbs and a long tail that is about the length of the rest of the body. A distinctive feature are scent glands on the underside of the tail, which are on average 29.5 mm long and thus take up almost a third of the length of the tail. This makes them noticeably larger than the other representatives of Macroscelides . The head is characterized by the typically long and flexible nose that is long and flexible and protrudes several millimeters forwards. The trunk is covered with short, fine hair, with the exception of the area around the nostrils. Due to its length, the tongue can be stretched out several millimeters in front of the tip of the nose. The eyes are relatively smaller than those of the other two species in the genus. In contrast to these, the ears do not protrude above the head and are therefore lower. Their length is 17 to 28 mm, the upper edge is much more rounded, and they have a noticeably deep indentation on the back. On the inside of the auricle, sparse, short, rust-colored hair grows, as well as on the edge, making the pink skin visible. In contrast to the other Macroscelides representatives, the skin does not show any dark pigmentation and is therefore characteristically lighter. The body fur appears dense and soft. On the back it has a light gray color, interspersed with a rusty brown tint. The hair here reaches around 10 mm in length and is darker at the base than at the tip. The peritoneum is characterized by a whitish hue, it extends from the chin to the buttocks, also pulls up on the sides of the body and also covers the upper leg sections. However, there is a rust-colored stain on both sides of the anal opening . The hair on the belly is 7 mm long and slightly shorter than on the back. The tail is generally sparsely hairy, but the fur coverage increases in the rear part, so that the tail end looks bushy. The length of the rust-colored hair is only 4 to 5 mm here. The base of the tail, on the other hand, is hairless. The tops of the feet are also only sparsely hairy, but the soles are bare. The hind foot has lengths of 27.5 to 30.5 mm.
distribution
The distribution area of the Etendeka short-eared elephant is limited to the Kunene region in northwestern Namibia . The species occurs in the so-called Etendeka Ignaeus Province , a landscape characterized by volcanic rocks that was formed around 133 million years ago. The first evidence of the Etendeka short-eared elephant was made from the central and eastern part of the Etendeka plateau and on Awahab , a witness mountain that is separated from the Etendeka plateau by the Huab river . The mountains reach heights of up to 1400 m, but in both find regions the animals occur at lower altitudes of 340 to 860 m, where they colonize scree slopes. The landscape is characterized by a desert-like dry climate with 50 to 100 mm annual precipitation and consists of a sparse, loosely spread vegetation of perennial grasses, low bushes up to 30 cm high and individual herbs. The extent of the inhabited area known at that time was 700 km², but due to the nature of the landscape a populated area of up to 3000 km² is assumed. Investigations in October 2013 also led to the detection of the species in the Gobobosebberge 40 km to the south , which also belong to the Etendeka Ignaeus Province . In addition, it could be observed in the westernmost and northernmost part of the Etendeka Plateau, the former area lies within the Skeleton Coast National Park . The three new sites substantially expand the range of the Etendeka short-eared elephant, the height distribution corresponds to the previous sightings. In the same area the Namib short-eared elephant ( Macroscelides flavicaudatus ) occurs sympathetically , but inhabits other micro- habitats .
Way of life
Hardly any data is available on the way of life of the Etendeka short-eared elephant, so far the species has only been known about three dozen individuals, 16 of which formed the basis for the initial description . Of the females observed so far, two were pregnant (February and November) and one gave milk (May). The litter size consists of two newborns. Of the first 16 individuals, three pairs were found in close proximity to each other, two of them comprised males and females, the third was a mother with cubs. According to investigations in the Gobobosebberge, the individual individuals maintain activity areas of 7.2 to 22.8 ha in size (14.9 ha on average). The spatial extent averages 425 m, in one extreme case it was 1.5 km. The size of the territories clearly exceeds that of the elephant in more densely overgrown landscapes. Data on the overlap are not yet available. The animals are strictly nocturnal and begin their activities between 7.15pm and 8.15pm. The movement profiles transmitted by radio transmitters indicate that the early hours of the night are used more intensively than the later ones. The animals spend the day under boulders or stones. The individual shelters are between 3 and 30 m apart within the action areas. They are not specially prepared, dug up or sprinkled with plant material, which corresponds to the behavior of the other representatives of Macroscelides or the elephant shrews ( Elephantulus ). Each individual uses their own shelter, which is changed daily. An animal rarely spends several days in a row in a hiding place. It is noticeable that the entrances are on the side opposite to the midday sun. As a result, the animals avoid the high levels of solar radiation at lunchtime, which saves energy during thermoregulation . Sometimes they also fall into a torpor . Under certain circumstances, bushes such as the stink bush serve as hiding places, but correspondingly large plants are rather rare in the area of distribution. So far, no evidence has been provided that the Etendeka short-eared elephant creates paths, as is known from the sympathetic Namib short-eared elephant , whose long and largely straight paths and paths connect the individual shelters and activity areas in the stony landscape. It is believed, however, that the Etendeka short-eared elephant uses traditional paths that are hardly visible in the rocky subsoil. Ticks and mites could be observed on individual individuals . The Cape fox appears as a potential predator .
Systematics
|
Internal systematics of elephants according to Heritage et al. 2020
|
The Etendeka short-eared elephant is a species from the genus Macroscelides . This contains two other species, of which the short-eared elephant ( Macroscelides proboscideus ) is the better known. Macroscelides is a member of the elephant family (Macroscelididae), a group of smaller mammals found only in Africa . Two subfamilies are distinguished within the elephant. One is the Rhynchocyoninae , which is monotypical and contains the proboscis ( Rhynchocyon ), which mainly inhabit wooded habitats. The second includes the Macroscelidinae , in which, in addition to Macroscelides , the elephant shrews ( Elephantulus ), the proboscis ( Petrodromus ), the Somali elephant shrew ( Galegeeska ) and the North African elephant shrew ( Petrosaltator ) are classified. These are more adapted to dry open landscapes to desert-like regions. Molecular genetic studies suggest a closer relationship between Macroscelides and Petrodromus and Petrosaltator . The separation of the two subfamilies occurred in the Lower Oligocene about 32.8 million years ago, while the Macroscelidinae diversified further in the Upper Ooligocene about 28.5 million years ago. The genus macroscelides can be genetically traced back to the Lower Miocene around 19.1 million years ago.
|
Internal systematics of Macroscelides according to Dumbacher et al. 2014
|
Since the second half of the 20th century, Macroscelides was regarded as monotypical and contained only the short-eared elephant. It was not until 2012 that a second species was established with the Namib short-eared elephant ( Macroscelides flavicaudatus ), which was characterized by different external characteristics and a range that was separated from the short-eared elephant and located at least 50 km further north. Genetic studies have also shown that no gene flow can be detected between the southern populations of the short-eared elephant and the northern populations of the Namib short-eared elephant . Furthermore, both species show different habitat uses. Renewed genetic analyzes also did not reveal any exchange of genes for the Etendeka short-eared elephant, neither with the short-eared elephant nor with the sympathetic Namib short-eared elephant. As a result of these studies, the three representatives of the genus Macroscelides each form a self-contained group, which means that they are now classified as separate species.
discovery
Between June 2005 and September 2011, researchers led by John P. Dumbacher undertook a total of nine field studies in northwestern Namibia. The first specimen of the Etendeka short-eared elephant was discovered in April 2006. The holotype (specimen number CAS MAM 29679) dates from October 5, 2009 and includes a complete individual. It was picked up on the Awahab- Zeugenberg at a height of around 720 m on a scree field dominated by basalts . The type locality is located around 28 km south of the Huab River and around 60 km northwest of the Brandberg massif . Five other paratypes in different states were recovered from the same site within a radius of about 1 km , one of which corresponds to the first discovered individual, the four others date to May 2010. At the time of the first description, a total of 16 individuals were known, including 10 Females, 4 males and 2 of undetermined sex (one individual was not yet fully grown). The species name micus is derived from the Greek word μικρός ( mikrós "small") and refers to the small body size.
Threat and protection
According to current knowledge, the Etendeka short-eared elephant is rather rare and endemic , which may have an impact on the population. However, human interference is very rare in the region and is restricted to areas that are more frequented by game hunters and tourists. In the future, however, factors such as increasing desertification due to grazing could also play a role. The IUCN and the Afrotheria Specialist Group , which belongs to it, assume that the population is currently “not at risk” ( least concern ). The species is present in local protected areas.
literature
- John P. Dumbacher, Galen B. Rathbun, Timothy O. Osborne, Michael Griffin and Seth J. Eiseb: A new species of round-eared sengi (genus Macroscelides) from Namibia. Journal of Mammalogy 95 (3), 2014, pp. 443-454
- 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 (pp. 229-230) ISBN 978-84-16728-08-4
Individual evidence
- ↑ Mike Perrin and Galen B. Rathbun: Genus Macroscelides - Round-eared Sengi. 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. 276-278
- ↑ a b c d e f g h John P. Dumbacher, Galen B. Rathbun, Timothy O. Osborne, Michael Griffin and Seth J. Eiseb: A new species of round-eared sengi (genus Macroscelides) from Namibia. Journal of Mammalogy 95 (3), 2014, pp. 443-454
- ↑ a b c 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 (pp. 229-230) ISBN 978-84-16728-08-4
- ^ A b Galen B. Rathbun and John P. Dumbacher: Macroscelides micus. The IUCN Red List of Threatened Species. Version 2015.2. ( [1] ); last accessed on July 1, 2015
- ^ Galen B. Rathbun, Timothy O. Osborne and Peter GR Coals: Distribution of the Etendeka round-eared sengi (Macroscelides micus), a Namibian endemic mammal. Journal of Namibia Scientific Society 63, 2015, pp. 153–157
- ↑ a b Galen B. Rathbun and John P. Dumbacher: Home range and use of diurnal shelters by the Etendeka round-eared sengi, a newly discovered endemic Namibian desert mammal. PeerJ 3, 2015, p. E1302 doi : 10.7717 / peerj.1302
- ↑ 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
- ↑ 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
- ↑ John P. Dumbacher, Elizabeth J. Carlen and Galen B. Rathbun: Petrosaltator gen. Nov., A new genus replacement for the North African sengi Elephantulus rozeti (Macroscelidea; Macroscelididae). Zootaxa 4136 (3), 2016, pp. 567-579
- ↑ John P. Dumbacher, Galen B. Rathbun, Hanneline A. Smit and Seth J. Eiseb: Phylogeny and Taxonomy of the Round-Eared Sengis or Elephant-Shrews, Genus Macroscelides (Mammalia, Afrotheria, Macroscelidea). Plos ONE 7 (3), 2012, p. E32410
- ^ Afrotheria Specialist Group: Another new sengi species. Afrotherian Conservation 10, 2014, p. 13
Web links
- Macroscelides Micus in the endangered Red List species the IUCN 2015 Posted by: Rathbun & Dumbacher, 2013. Retrieved on July 1, 2015.