Gray-faced elephant dog
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Gray-faced elephant dog ( Rhynchocyon udzungwensis ) |
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| Rhynchocyon udzungwensis | ||||||||||||
| Rovero , Rathbun , Perkin , Jones , Ribble , Leonard , Mwakisoma & Doggart , 2008 |
The gray-faced elephant dog ( Rhynchocyon udzungwensis ) is a species of mammal from the family of elephants (Macroscelididae). It is the largest representative of this group and was scientifically described in 2008. Like other elephants, the species is characterized by an elongated, trunk-like nose and short front and long hind legs. Its distribution area is limited to the Udzungwa Mountains in East Africa , where it predominantly inhabits moist mountain rainforests. The way of life has hardly been researched so far. The population of the gray-faced proboscis dog is classified as threatened.
features
Habitus
The gray-faced trunk dog is the largest representative of the trunk dog with a total length of 55 to 58 cm. It reaches a head-trunk length of 29.7 to 31.8 cm, a tail length of 23.9 to 26.2 cm and a weight of 658 to 750 g. In terms of body size, it exceeds the other representatives of the genus by 10 to 20%, based on weight by 25 to 50%. Like all trunk dogs, the gray-faced trunk dog is characterized by the long, trunk-shaped elongated nose, as well as by the long and thin legs, in which the hind limbs are longer than the front ones. The fur is smooth, coarse and thin and relatively colored. The front 20 mm of the trunk are hairless and black, the back part of the trunk and the face up to about the root of the ear are gray. The individual hairs have black bases and cream-colored to light gray tips. The ears themselves are 31 to 37 mm in size and are also bare and dark in color. A chestnut brown mane begins between the ears and runs down the nape of the neck. The hair here reaches up to 25 mm in length when erect and protrudes 10 mm beyond the tips of the ears. The chestnut brown color continues as a central stripe on the back to near the base of the tail. Gray-yellow to gray-reddish-brown colors predominate behind the ears and shoulders, which merge into a reddish-brown coloration in the area of the sides of the body, in which gray tones no longer appear. The gray tint on the shoulders is mainly caused by the black tips of the hair there. Sometimes an inconspicuous pattern of spots can be formed on the back, as it sometimes occurs in the red-shouldered elephant dog ( Rhynchocyon petersi ) and the golden elephant dog ( Rhynchocyon chrysopygus ). The chest and chin are light yellow to cream-colored, the fur here is much thicker than on the sides. Towards the belly it becomes thinner and the tint changes to a faint reddish brown. The inside of the forelegs is a mixture of the light yellow chest hair and the reddish brown flank hair. On the inside of the hind limbs, like the belly, lighter reddish brown colors dominate, while the outside hind legs are raven black up to the thighs. The skin of the tail is black on the top and dark brown on the underside. In addition, a white ring 4 to 6 cm wide is formed near the end of the tail. The tail's coat is very thin, the color of the tail is reflected in the tail hair. The feet generally appear black, but they are covered with short reddish brown hair on the back. The rear foot length varies between 79 and 88 mm.
Dentition features
The dentition has a total of 34 to 36 teeth. The dental formula is as follows: . The length of the upper row of teeth is between 30.2 and 32.6 mm. A slight gender dimorphism can be seen in the expression of the upper canine . In males these are 6.3 to 7.2 mm long, in females 5.9 to 6.5 mm.
distribution and habitat
The gray-faced elephant dog has so far only been recorded from the Udzungwa Mountains in central Tanzania . Two separate populations are known, one of which is in the Ndundulu-Luhomero forest in the central north, the other in the Mwanihana forest in the east of the mountains. Both landscape zones are characterized by dense forests with a closed canopy. They include the submontane to high-montane altitude ranges, the trees in the lower layers are 25 to 50 m tall, in the upper layers from 10 to 25 m. The underground vegetation is different, from more open areas to thick bushes. Between the two landscape areas there is a 20 to 25 km wide strip of grass and woodland. The gray-faced proboscis dog prefers moist, evergreen mountain forests to a large extent and is rarely found in lower dry forests. It also avoids steep slopes with little vegetation cover and is more likely to be found on gentle climbs. According to initial studies, the elevation in the Ndundulu – Luhomero forest ranged from 1350 to 2300 m and in the Mwanihana forest from 1000 to 1700 m. Further observations could prove the species in the Mwanihana forest also at very low altitudes around 400 m, in the Ndundulu – Luhomero forest it rises up to 2500 m. This allows a total distribution area of 390 km² to be determined, of which 268 km² are accounted for by the Ndundulu – Luhomero forest and 122 km² by the Mwanihana forest . The population density is assumed to be around 50 to 80 individuals per square kilometer, which corresponds to the known average of the other proboscis dogs. The entire distribution area of the gray-faced proboscis dog lies within that of the spotted proboscis dog ( Rhynchocyon cirnei ), which occurs in the Udzungwa Mountains at altitudes of 290 to 1800 m. Actual overlaps between the two species are only known in the central Mwanihana forest .
Way of life
Little information is available about the way of life of the gray-faced elephant. According to previous observations, it is only active during the day with the main activity times from 7:30 a.m. to 5:30 p.m. Like other elephants, it also creates nests that are set up in small, oval depressions in the ground and are lined with leaf material, with a pile piled up in the middle. They are usually located under trees at the base of the trunks. The diet consists mainly of insects . A pregnant female carried two fetuses , one in each horn of the uterus . In field studies it was observed that the Schmätzer of the species Alethe fuelliborni , which is also insectivorous, follows the gray-faced proboscis dog. It is not yet known whether there is a kind of commensalism here , as has been shown with other elephant dogs.
Systematics
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Internal systematics of elephants according to Heritage et al. 2020
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The gray-faced proboscis dog is a species from the genus of the proboscis dog ( Rhynchocyon ), to which four other species belong. The proboscis dogs form part of the family of the elephants (Macroscelididae) within the order of the same name (Macroscelidea). The family includes smaller mammals that are endemic to Africa . It consists of a total of six genera and two subfamilies. The proboscis dogs belong to the subfamily of the Rhynchocyoninae and are their only member, so it is monotypical . All representatives of the elephant dog mostly inhabit forested habitats , they represent the largest forms within the elephant. The second subfamily, the Macroscelidinae , includes the elephant shrews ( Elephantulus ), the proboscis ( Petrodromus ) and the genera Macroscelides , Galegeeska and Petrosaltator . These are significantly smaller members of the elephants who are adapted to rather dry to sometimes desert-like regions. According to molecular genetic studies, the separation of the two subfamilies took place in the Lower Oligocene , about 32.8 million years ago. A greater diversification of the genus Rhynchocyon began in the late Middle Miocene around 9.7 million years ago.
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Internal systematics of the proboscis dogs according to Carlen et al. 2017
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Relationship within the gray-faced proboscis dog according to Lawson et al. 2013
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The closest relative of the gray-faced proboscis dog is the spotted proboscis dog ( Rhynchocyon cirnei ). The distribution areas of the two species overlap slightly in the Udzungwa Mountains, but the latter species copes better with the drier lowland conditions. Genetic studies show that both species are monophyletic and can therefore be viewed as independent. However, based on the mitochondrial DNA , a clear introgression of genes of both types could be detected. Since there are no morphological transitional forms, current hybridization can be ruled out. It is assumed that this gene exchange possibly took place in the course of the last warm - cold cycle beginning around 120,000 years ago. During this cycle, the expansion of the areas of both the gray-faced and the spotted proboscis was subject to more pronounced changes as a result of the more severe climatic fluctuations, which led to more frequent contact between the two species, which promoted introgression.
discovery
After several researchers reported observations of a previously unknown species of elephant during the investigations into the biodiversity of the Udzungwa Mountains, in 2005 it was possible for the first time to document individual animals by automatic camera traps. A first publication followed the following year, mentioning the new species possible at the time. The Udzungwa Mountains are part of the Eastern Arc Mountains of East Africa, which represent an important biodiversity hotspot with numerous endemic species such as the Kipunji monkey or the Phillips Congo shrew . More than 70 medium to large mammal species are known from the Udzungwa Mountains alone. The formal scientific first description of the gray-faced proboscis dog under the scientific name Rhynchocyon udzungwensis was made by Francesco Rovero and research colleagues in February 2008. The Vikongwa river valley in the Ndundulu Forest at an altitude of about 1350 m was determined as the type region . The holotype (specimen number CAS 28043) comprises an adult female that was collected in mid-March 2006. The scientific species name udzungwensis is a reference to the range of the gray-faced proboscis dog.
Threat and protection
The IUCN lists the gray-faced proboscis dog as "endangered" ( vulnerable ). The reasons for this lie in the very limited distribution area and its susceptibility to natural and artificially caused forest fires, which can lead to rapid habitat loss. The species is found entirely within the Udzungwa Mountains National Park and the Kilombero Scarp Forest Reserve to the west . The peripheral areas are strongly influenced by the increasing population. The population is estimated to be 15,000 to 24,000 individuals, the assumption is based on the assumed density of 50 to 80 animals per square kilometer and the initially assumed size of the distribution area of 300 km². Further investigations were able to expand the occurrence by about a third. A system of several hundred camera traps in the protected areas enables further observation and research into the way of life and distribution of the gray-faced elephant dog.
literature
- 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. 228) ISBN 978-84-16728-08-4
- F. Rovero, GB Rathbun, A. Perkin, T. Jones, DO Ribble, C. Leonard, RR Mwakisoma and N. Doggart: A new species of giant sengi or elephant-shrew (genus Rhynchocyon ) highlights the exceptional biodiversity of the Udzungwa Mountains of Tanzania. Journal of Zoology 274 (2), 2008, pp. 126-133 doi: 10.1111 / j.1469-7998.2007.00363.x
Individual evidence
- ↑ a b c d e f Francesco Rovero, Galen B. Rathbun, A. Perkin, T. Jones, DO Ribble, C. Leonard, RR Mwakisoma and N. Doggart: A new species of giant sengi or elephant-shrew (genus Rhynchocyon ) highlights the exceptional biodiversity of the Udzungwa Mountains of Tanzania. Journal of Zoology 274 (2), 2008, pp. 126-133
- ↑ 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. 228) ISBN 978-84-16728-08-4
- ^ Francesco Rovero and Galen B. Rathbun: Gray-faced sengi research update. Afrotherian Conservation 7, 2009, pp. 16-17
- ↑ a b Francesco Rovero, Leah Collett, Silvia Ricci, Emanuel Martin and Daniel Spitale: Distribution, occupancy, and habitat associations of the gray-faced sengi (Rhynchocyon udzungwensis) as revealed by camera traps. Journal of Mammalogy 94 (4), 2013, pp. 792-800
- ↑ a b Francesco Rovero: Gray-faced sengi research update. Afrotherian Conservation 10, 2014, pp. 11-13
- ↑ 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
- ^ 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
- ^ 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
- ^ HA Smit, B. 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
- ↑ Elizabeth J. Carlen, Galen B. Rathbun, Link E. Olson, Christopher A. Sabuni, William T. Stanley and John P. Dumbacher: Reconstructing the molecular phylogeny of giant sengis (Macroscelidea; Macroscelididae; Rhynchocyon). Molecular Phylogenetics and Evolution 113, 2017, pp. 150-160
- ↑ a b Lucinda P. Lawson, Cristiano Vernesi, Silvia Ricci and Francesco Rovero: Evolutionary History of the Gray-Faced Sengi, Rhynchocyon udzungwensis, from Tanzania: A Molecular and Species Distribution Modeling Approach. PLoSONE 8 (8), 2013, p. E72506 doi: 10.1371 / journal.pone.0072506
- ↑ Francesco Rovero and Galen Rathbun: A Potentially New Giant Sengi (Elephant-Shrew) from the Udzungwa Mountains, Tanzania. Journal of East African Natural History 95 (2), 2006, pp. 111-115.
- ^ F. Rovero and N. Doggart: Rhynchocyon udzungwensis. The IUCN Red List of Threatened Species. Version 2015.1. ( [1] ); last accessed on June 12, 2015
Web links
- Rhynchocyon udzungwensis inthe IUCN Red List of Threatened Species 2013.2. Listed by: Rovero, F. & Doggart, N., 2008. Retrieved January 22, 2014.