Nesogale

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Nesogale
Systematics
Superordinate : Afrotheria
without rank: Afroinsectiphilia
Order : Tenrecus (Afrosoricida)
Family : Tenreks (Tenrecidae)
Subfamily : Travel treks (Oryzorictinae)
Genre : Nesogale
Scientific name
Nesogale
Thomas , 1918

Nesogale is a genus of mammals from the Reistenreks group within the Tenreks family(Tenrecidae). It includes the Dobsonian and Talazac Kleintenrek , both species are on average slightly larger than most representatives of the Kleintenreks , which are considered the closest relatives. Like these, they resemblethe shrews in their habitus and have a spindle-shaped body with short limbs and a long, narrow head with a pointed snout. The tail becomes about as long as the rest of the body, the fur is typically soft. Both species are endemic to eastern Madagascar and inhabit tropical rainforests from the lowlands to high mountains. The animals live solitary and live on the ground, but can also climb trees. Their diet consists of insects and invertebrates . The offspring are born in litters of up to five boys. These are nestlings that grow out over a period of about three months. The genus was introduced in 1918, but was considered identical to the Kleintenreks, especially in the second half of the 20th century. Only a genetic study from 2016 raised Nesogale to its own genusstatus.

features

Habitus

The two representatives of the genus Nesogale are on average somewhat larger than the closely related Kleintenreks ( Microgale ). Their total length varies from 17.3 to 26.8 cm, of which 8.3 to 12.8 cm are the head-trunk length and 8.8 to 15.1 cm are the tail length. The smaller Dobsonian Kleintenrek ( Nesogale dobsoni ) weighs on average 27.1 g, the larger Talazac Kleintenrek ( Nesogale talazaci ) has an average weight of 37.6 g. Both species are outwardly very similar and correspond in appearance to the other Kleintenreks. They have a shrew-like habit with a spindle-shaped body, strong short limbs and a long, narrow head that tapers to the front. The tail becomes about as long as the body or slightly longer than it. The back fur has a soft texture and is brownish to dark brown in color, with reddish-brown washings sometimes occurring. The underside is lighter in color. The hand and foot each have five rays with powerful claws. The three central rays are most strongly developed. Six leathery skin pads are developed on the underside. The rear foot length corresponds to about 21% of the body length.

Skull and dentition features

The skull is similar to that of the Kleintenreks, but is much more massive. It reaches a length of 28.8 to 37.7 mm and a width at the skull of 10.9 to 12.9 mm. In the side view, the front line is slightly sinusoidal . As with all tenreks, the zygomatic arch is not closed. The rostrum has a broad shape, the rear part of the skull looks somewhat shortened compared to the small tenreks; the ratio of the anterior to the posterior skull is 0.55 to 0.45. The eye region is hardly constricted, the edges of the skull have a parallel course when viewed from above. The occiput is markedly angled. The striking bone ribs as muscle attachment points in the area of ​​the upper neck line are particularly striking. The dentition consists of 40 teeth with the following dental formula . In general, the teeth are very strong and large. In the anterior upper dentition, there are diastemas between the first and second incisors and between the third and canine teeth . In contrast to numerous small tenreks, there are no further gaps in the premolars in Nesogale . Likewise, the additional cusps that appear on the crowns of the front teeth of the Kleintenreks are rather weak or not at all developed in the Nesogale species. In the upper row of teeth the first incisor is larger than the second, in the lower jaw the second incisor clearly protrudes over the canine. The rear dentition shows hardly any deviations from that of the Kleintenreks. The molars are characterized by a zalambdodontic chewing surface pattern, which consists of three main cusps (para-, proto- and metaconus; based on the maxillary molars) in a triangular arrangement, the paraconus has a particularly large and pyramidal design. The last upper molar is characteristically reduced in size.

Skeletal features

The spine consists of 7 cervical, 16 thoracic, 6 lumbar, 2 sacrum and 29 tail vertebrae. The representatives of the genus Nesogale have a relatively standardized skeleton in relation to other tenreks, so that only a few special adaptations can be found in the front limbs. The shoulder blade is rather short and wide and not as long and narrow as in digging forms. There is also no prominent deltopectoral ridge on the humerus as a starting point for strong arm and shoulder muscles. The ulna has a short upper articular process, the olecranon , which takes up only about 12% of the length of the total bone. The hand has the full number of carpal bones in the Tenreks, so that, unlike some burrowing species, no adhesions occur here. The metacarpal and finger bones are long and narrow, the claws have a short and curved shape.

distribution

The genus Nesogale is endemic to Madagascar . The distribution areas of the two representatives extend in a more or less wide strip over the eastern parts of the country and overlap in wide areas, so that both forms appear sympatric in many places . The animals inhabit tropical rainforests of the lowlands up to high mountain areas, whereby the Dobsonian Kleintenrek can also be found above the tree line. In contrast to the small tenreks of the genus Microgale , the Nesogale species do not occur in the dry west of the island state. Both the Dobsonian and Talazac Kleintenrek are among the most commonly recorded tenreks.

Way of life

General

The way of life of the representatives of the genus Nesogale is comparatively well investigated, which is mainly due to field and laboratory studies of the 1960s. The animals live on the ground and move four-footed forward in the cloister . Occasionally they also climb trees. Despite their relative frequency, they tend to live hidden and use leaf waste as a retreat or build underground burrows in which there is a nest made of plant material. It is known that the Dobson-Kleintenrek uses echolocation to orient itself . In general, the animals are solitary, encounters between their peers take place in a ritualized manner in that they probe each other with their noses. The defense behavior consists of a wide open mouth, occasionally sounds in the form of high-pitched squeaks or trills are uttered.

Diet and Metabolism

The main diet is made up of insects and invertebrates ; in human captivity, the Nesogale species also ate smaller vertebrates . The prey is mostly searched on the ground and caught with the mouth or the front feet. Storage stores are not set up, but the Dobsonian Kleintenrek is able to store larger fat reserves in the tail and under the skin, which are then used up during the dry phases with less food available. The body temperature is not constant and largely adapts to the outside temperatures, torpor does not occur. The fluctuations in body temperature are lower in the Talazac-Kleintenrek than in the Dobson-Kleintenrek. In both species, the metabolism reaches about three quarters of the value that would be expected in similarly sized mammals. It increases particularly in times of higher stress. In females, this mostly falls during the pregnancy or lactation phase . According to studies, the body temperature is more stable during these phases, which possibly causes the increased metabolism.

Reproduction

Reproduction has so far only been studied in human care. The gestation period lasts around 62 to 63 days, a litter comprises one to five young animals that are born as nestlings naked and with closed eyes and ears. The offspring spends the first time in a separate nest made of plant material. Little information is available about parental care and the sire does not participate in rearing. The eyes open after about three weeks, from this point onwards the boys eat more solid food. They are fully grown at around three months. Life expectancy in the wild is unknown.

Systematics

Internal systematics of the Tenreks according to Everson et al. 2016
 Tenrecidae  
  Tenrecinae  


 Echinops


   

 Setifer



   

 Hemicentetes


   

 Tenrec




   
  Geogalinae  

 Geogals


  Oryzorictinae  

 Oryzorictes


   
  Nesogale  

 Nesogale dobsoni


   

 Nesogale talazaci



   

 Microgale






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Nesogale is a genus within the Tenreks family (Tenrecidae). It also forms together with the rice burrowers ( Oryzorictes ) and the small tenreks ( Microgale ) the rice treks (Oryzorictinae), one of the three subfamilies of the tenreks. The other two are represented by the spiky hedgehog tenreks (Tenrecinae) and the monotypical earth tenreks (Geogalinae). The Kleintenreks, which are very varied and include around two thirds of today's representatives of the Tenreks, represent the closest relatives of Nesogale according to molecular genetic analyzes . Similarities can be found, among other things, in the construction of the front dentition with the canine, which is rather unspecialized compared to the incisors. According to genetic analyzes, the two genera separated from each other in the Lower Miocene , about 19.4 million years ago. The splitting of Nesogale into the lines that exist today dates back to the Upper Miocene around 7 million years ago.

There are 2 types:

The genus Nesogale was first scientifically described in 1918 by Oldfield Thomas . To this end, he split the Kleintenreks, which at that time already included around a dozen species, into several genera (in addition to Nesogale , Thomas also introduced Leptogale , but this is not recognized) and relegated the Talazac and Dobsonian Kleintenrek to the new form , the latter represents the nominate form. As distinguishing features of Nesogale compared to Microgale , Thomas cited the generally larger physique and, above all, the more robust skull with distinctive muscle attachment points and stronger dentition.

Research history

The independence of the genus Nesogale was assessed differently in the subsequent period. Until the 1940s, only a few individuals of the genus were known, so it was considered unsatisfactory. Terence Morrison-Scott was able to add several new specimens in 1948 that had been collected during expeditions to Madagascar in the 1920s to 1940s. He revised the two species and confirmed the genus status of Nesogale . Later authors, however, viewed this critically, such as John F. Eisenberg and Edwin Gould , who only led Nesogale as a subgenus of Microgale in 1970 . At around the same time, Henri Heim de Balsac formally abolished the genus and reunited Nesogale with Microgale . In a comprehensive revision of the Kleintenreks from 1987, Ross DE MacPhee largely followed Heim de Balsac and synonymized Nesogale with Microgale . MacPhee underpinned this step with numerous morphological and morphometric investigations, in which he was only able to work out a few deviating features. The status quo remained after this revision for the next nearly three decades there are individual molecular genetic analysis supported the early 21st century, the close relationship of Dobson and Talazac-microgale with the other Microgale species. The genetic studies also revealed that the Kleintenreks did not form a natural unit. The reason for this was the deep embedding of the water tarnrect ( Microgale mergulus ), which was originally listed in the genus Limnogale , in Microgale . As a possible way out, it was considered to incorporate Limnogale into Microgale and / or to recognize Nesogale as independent again, but this required further studies. In 2016, a molecular genetic analysis was published that included all known representatives of the Tenreks for the first time. In this, the Dobsonian and Talazac Kleintenrek formed the sister group of the other Kleintenreks including the water tenreks. The early separation of the two species from the other members of Microgale , which was also established, prompted the authors to reassign Nesogale to genus status and to incorporate the Dobson and Talazac Kleintenrek there.

Threat and protection

Both species of the genus Nesogale are classified by the IUCN in the category “not threatened” ( least concern ). The assessment is based on the wide distribution and the assumed large population of both species. They are also present in numerous protected areas. Regionally, the destruction of forests through conversion into agricultural land or through logging can have an impact on stocks.

literature

  • JF Eisenberg and Edwin Gould: The Tenrecs: A Study in Mammalian Behavior and Evolution. Smithsonian Institution Press, 1970, pp. 1-138
  • Kathryn M. Everson, Voahangy Soarimalala, Steven M. Goodman and Link E. Olson: Multiple loci and complete taxonomic sampling resolve the phylogeny and biogeographic history of tenrecs (Mammalia: Tenrecidae) and reveal higher speciation rates in Madagascar's humid forests. Systematic Biology 65 (5), 2016, pp. 890-909 doi: 10.1093 / sysbio / syw034
  • Ronald M. Nowak: Walker's Mammals of the World . The Johns Hopkins University Press, Baltimore 1999, ISBN 0-8018-5789-9
  • RDE MacPhee: The Shrew Tenrecs of Madagascar: Systematic Revision and Holocene Distribution of Microgale (Tenrecidae, Insectivora). American Museum Novitates 2889, 1987, pp. 1-45

Individual evidence

  1. ^ PJ Stephenson: Taxonomy of shrew-tenrecs (Microgale ssp.) From eastern and central Madagascar. Journal of Zoology 235, 1995, pp. 339-359
  2. ^ Paulina D. Jenkins, Steven M. Goodman, and Christopher J. Raxworthy: The Shrew Tenrecs (Microgale) (Insectivora: Tenrecidae) of the Réserve Naturelle Intégrale d'Andringitra, Madagascar. Fieldiana Zoology 85, 1996, pp. 191-217
  3. ^ A b Steven M. Goodman and Paulina D. Jenkins: The Insectivores of the Réserve Spéciale d'Anjanaharibe-Sud, Madagascar. Fieldiana Zoology 90, 1998, pp. 139-161
  4. ↑ Steven M. Goodman, Paulina D. Jenkins and Mark Pidgeon: Lipotyphla (Tenrecidae and Soricidae) of the Réserve Naturelle Intégrale d'Andohahela, Madagascar. Fieldiana Zoology 94, 1999, pp. 187-216
  5. ^ A b Steven M. Goodman and Paulina D. Jenkins: Tenrecs (Lipotyphla; Tenrecidae) of the Parc National de Marojejy, Madagascar. Fieldiana Zoology 97, 2000, pp. 201-229
  6. ↑ a b c d e J. F. Eisenberg and Edwin Gould: The Tenrecs: A Study in Mammalian Behavior and Evolution. Smithsonian Institution Press, 1970, pp. 1-138
  7. ↑ a b c Wilhelm Leche: On the history of the development of the mammalian tooth system, at the same time a contribution to the tribal history of this group of animals. Part two: phylogeny. Second booklet: Families of the Centetidae, Solenodontidae and Chrysochloridae. Zoologica 20, 1906/1908, pp. 1–157 ( [1] )
  8. ↑ a b c R. DE MacPhee: The Shrew Tenrecs of Madagascar: Systematic Revision and Holocene Distribution of Microgale (Tenrecidae, Insectivora). American Museum Novitates 2889, 1987, pp. 1-45
  9. ↑ a b Oldfield Thomas: On the arrangement of the small Tenrecidae hitherto referred to Oryzorictes and Microgale. Annals and magazine of natural history 14, 1918, pp. 302–307 ( [2] )
  10. ^ A b T. CS Morrison-Scott: The Insectivorous Genera Microgale and Nesogale (Madagascar). Proceedings of the Zoological Society of London 118, 1948, pp. 817-822
  11. ^ Justine A. Salton and Eric J. Sargis: Evolutionary morphology of the Tenrecoidea (Mammalia) carpal complex. Biological Journal of the Linnean Society, 93, 2008, pp. 267-288
  12. ^ Justine A. Salton and Eric J. Sargis: Evolutionary Morphology of the Tenrecoidea (Mammalia) Forelimb Skeleton. In: EJ Sargis and M. Dagosto (Eds.): Mammalian Evolutionary Morphology: A Tribute to Frederick S. Szalay, Springer Science, 2008, pp. 51-71
  13. ^ A b P. J. Stephenson, Voahangy Soarimalala and Steven M. Goodman: Microgale dobsoni. The IUCN Red List of Threatened Species 2016. e.T40587A97190623 ( [3] ); last accessed on December 25, 2016
  14. ^ A b P. J. Stephenson, Voahangy Soarimalala and Steven M. Goodman: Microgale talazaci. The IUCN Red List of Threatened Species 2016. e.T41315A97202475 ( [4] ); last accessed on December 8, 2016
  15. ^ Edwin Gould: Evidence for echolocation in the Tenrecidae of Madagascar. Proceedings of the American Philosophical Society 109 (6), 1965, pp. 352-360
  16. ^ A b Edwin Gould and John F. Eisenberg: Notes on the biology of the Tenrecidae. Journal of Mammalogy 47 (4), 1966, pp. 660-686
  17. ^ A b Peter J. Stephenson, Paul A. Racey and Félix Rakotondraparany: Maintenance and reproduction of tenrecs (Tenrecidae) at Parc Tsimbazaza, Madagascar. International Zoo Yearbook 33, 1994, pp. 194-201
  18. ^ Peter J. Stephenson and Paul A. Racey: Reproductive energetics of the Tenrecidae (Mammalia: Insectivora). II. The shrew-tenrecs, Microgale spp. Physiological Zoology 66 (5), 1993, pp. 664-685
  19. ^ PJ Stephenson, JR Speakman and PA Racey: Field metabolic rate in two species of shrew-tenrec, Microgale dobsoni and M. talazaci. Comparative Biochemistry and Physiology 107A (2), 1994, pp. 283-287
  20. ↑ a b c d Kathryn M. Everson, Voahangy Soarimalala, Steven M. Goodman and Link E. Olson: Multiple loci and complete taxonomic sampling resolve the phylogeny and biogeographic history of tenrecs (Mammalia: Tenrecidae) and reveal higher speciation rates in Madagascar's humid forests. Systematic Biology 65 (5), 2016, pp. 890-909 doi: 10.1093 / sysbio / syw034
  21. ↑ Oldfield Thomas: Description of a new species of Microgale. The Annals and magazine of natural history 14, 1884, pp. 337-338
  22. ^ CI Forsyth Major: Diagnoses of new mammals from Madagascar. Journal of Natural History 18 (106), 1896, pp. 318–321 ( [5] )
  23. ^ Henri Heim de Balsac: Insectivores. In: R. Battistini and G. Richard-Vindard (eds.): Biogeography and ecology in Madagascar. The Hague, 1972, pp. 629-660
  24. ↑ Link E. Olson and Steven M. Goodman: Phylogeny and biogeography of tenrecs. In: Steven M. Goodman and Jonathan P. Benstead (Eds.): The natural history of Madagascar. University of Chicago Press, 2003, pp. 1235-1242
  25. ^ Matjaž Kuntner, Laura J. May-Collado and Ingi Agnarsson: Phylogeny and conservation priorities of afrotherian mammals (Afrotheria, Mammalia). Zoologica Scripta 40 (1), 2011, pp. 1-15

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