Comb rats
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| Ctenomyidae | ||||||||||||
| Lesson , 1842 | ||||||||||||
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| Ctenomys | ||||||||||||
| Blainville , 1826 |
The comb rats or Tukotukos ( Ctenomys , Ctenomyidae) are a genus and family of rodents that live in South America . They are burrowing animals that live underground and usually live solitary in their burrows. The internal system is controversial, there are almost 70 different types.
features
general characteristics
Comb rats have compact and muscular bodies that are adapted to the underground way of life. With their adaptations to a burrowing way of life, they are strongly reminiscent of the North American pocket mice , to which they are only distantly related. They reach a head body length of 15 to 25 centimeters, the tail is an additional 6 to 11 centimeters long. The weight varies between 100 and 700 grams. Their fur is usually thick; depending on the species, it can be gray, brown or almost black in color, with the underside usually being lighter. In some species there may be a light-colored collar, in some other species there are light or dark spots behind the ears or on other parts of the body. On the abdomen, there may be bright spots in the armpits or lumbar region. Body sizes as well as coat colors and skull dimensions vary greatly within the species.
The body is cylindrical, the tail, as in many underground animals, is short and barely hairy. The head is massive, the scarcely detached neck short and muscular. The legs are generally short and are used primarily for digging and for moving within the narrow corridors of the animals' living quarters. The front legs are slightly shorter than the rear legs. All toes have long claws, whereas those of the front paws are slightly longer. There are comb-like bristles on the hind paws, which are used to clean the fur of earth. The eyes are small, but comparatively large compared to all other small mammals living underground. They sit on top of the head, so the animals only have to stick their heads out of a hole in the ground to look around. The ear openings and the auricles are very small. The tail is comparatively short and thick, cylindrical with a broad base.
Features of the skull and skeleton
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The skull of the crested rats is usually compact and short, but it varies in size and in the ratio of different parts to each other. Like all guinea pig relatives , the comb rats have one incisor , one premolar and three molars in each upper and lower jaw , so they have a total of 20 teeth. Between the incisors, which have been transformed into strong incisor teeth , and the premolars, there is a tooth gap ( diastema ) that is typical of rodents . The arrangement of the cusps on the molars is kidney-shaped, the rearmost molar is smaller.
The shape of the skull is usually associated with the shape of the upper incisors. These are large and thick, they are colored bright orange on the front by a strong layer of enamel and protrude from this even when the mouth is closed. Like the front feet, they are also trained to dig and the animals are able to use them even when their mouths are closed. In some species they are correspondingly protruding ( proodont ), but they can also be horizontal or even slightly inward. Depending on the location and burial activity, the jaw muscles attached to the head and thus also the width and shape of the zygomatic arches and the muscle attachment points on the brain skull are pronounced.
Genetic traits
The comb rats are also characterized by a very high variability of the chromosome numbers , which range from 2n = 10 in the Steinbach comb rat ( Ctenomys steinbachi ) to 2n = 70 chromosomes in the D'Orbigny comb rat ( Ctenomys dorbignyi ) and often within the Species can vary greatly. This means that they have the greatest variability in the number of chromosomes in a genus within mammals.
distribution and habitat
Comb rats are native to southern South America, their range extends from southern Peru and central Brazil to Tierra del Fuego . They are found in a range of habitats from the tropics to the sub-Antarctic regions. They often live in grasslands and forests, but also, for example, in the Altiplano and in mountain regions and mountains. In the Altiplano in southern Peru and Bolivia they occur at altitudes of over 4,000 meters, in other regions such as Chile, Argentina and in eastern Brazil they can be found in the lowlands down to sea level.
Most of the species of the genus have a very limited and local distribution due to the highly fragmented habitats in the Andes and are not infrequently only proven at individual sites. Only a few species have larger ranges and can be found over wider areas. Comb rats live in relatively small populations that are separated from other populations by areas with unsuitable soil conditions or other barriers such as rocks or rivers. This has led to the emergence of a large number of species, the systematic classification of which remains under discussion.
Naming
The scientific name is derived from the comb-like bristles on the rear paws of the comb rats ( ancient Greek κτείς / κτενός kteís / ktenós , German 'comb' , ancient Greek μῦς mŷs , German 'mouse' ), which also gave it its German (and French) name .
Way of life
The burrows of the crested rats consist of a long, sometimes slightly curved main tunnel, from which side passages branch off, which either end in dead ends or lead to feeding places on the surface. The main tunnel can be 14 meters long, has a diameter of around 5 to 7 centimeters and runs around 30 centimeters below the surface of the earth. Below the main tunnel there is a grass-clad sleeping chamber, next to it there are several chambers in which food is stored. The exits on the surface can be marked with piles of earth, sometimes the animals close them when they are under construction.
Most burial activity occurs during the day, mostly in the early morning and late afternoon. The earth is loosened with the front feet and scraped back with the hind feet. With their teeth, they cut through roots that are in the way. Most species live solitary, but there have been isolated reports of several females living in a common den. Males, on the other hand, are considered more territorial and aggressive.
The name Tukotukos is an onomatopoeic approximation of the sound that the males utter and which presumably marks the territory. The sound actually sounds like "tlok-tlok-tlok", it lasts 10 to 20 seconds and becomes faster towards the end.
nutrition
Comb rats are pure herbivores that feed on various parts of plants such as roots, tubers, stems, grasses and others. Some plants such as stems and grasses they pull into the burrow from below, others try to reach them from the entrances to their burrows. But they rarely leave their burrow completely.
Reproduction
Little is known about the reproduction of most species. Usually the females only have one litter a year, rarely two. In many cases, the time of birth falls in the rainy season when there is plenty of food. The gestation period is around 100 to 120 days and the litter size one to seven.
Evolution and systematics
Tribal history
Today's crested rats consist of only one recent genus, Ctenomys , which consists of around 70 species. They come from the guinea pig relatives of South America and have adapted to the burrowing and underground way of life over several steps since the Miocene. They probably separated from other taxa of the lineage in the Pliocene . Among the closer relatives fossil genera include Eucelophorus from the middle Pliocene into the Pleistocene , Xenodontomys and Actenomys from the late Miocene until the Pliocene, Praectenomys from the Pliozähn and as a sister group looked to recent tuco-tuco species Paractenomys , also from the Pliocene . In 2020 the subfossil crested rat species Ctenomys viarapaensis was described from the Holocene of Argentina.
Species formation and adaptive radiation are considered to be one of the fastest species splitting processes within a recent mammal genus. The processes of speciation and the reasons for this are the subject of intensive research, with genetics and molecular biology playing a central role.
External system
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The crested rat family was established by René Primevère Lesson in 1842 and contains only one recent genus, the genus Ctenomys established by Henri Marie Ducrotay de Blainville in 1826 . The comb rats are counted among the guinea pig relatives within the rodents . Their sister group are the Trug rats , as their subfamily they are sometimes classified.
Internal system
The internal system is confusing and is in constant revision. Early studies of systematics and taxonomy were based on coat color, general morphological analyzes of the skull, and other features of the body. Later, cytological and molecular biological features such as chromosome number, allozyme and DNA sequences as well as the sperm shape were used to study the systematics and biogeography of these rodents. The species differ considerably in the number of chromosomes with karyotypes from 2n = 10 to 2n = 70 chromosomes, but are morphologically very similar. On the basis of morphological differences, the comb rats were divided into three subgenus, the subgenus Chacomys only containing the Conover comb rat ( Ctenomys conoveri ) and the subgenus Haptomys only the white- toothed comb rat ( Ctenomys leucodon ), while all other species are assigned to the subgenus Ctenomys become. On the basis of molecular biological investigations, however, the separation is not tenable. Today numerous species groups have been formed within the genus on the basis of DNA.
While Wilson & Reeder (2005) listed around 50 species, the Handbook of the Mammals of the World lists 69 species of the genus.
- Anderson crested rat ( Ctenomys andersoni ) occurs in the southern center of Bolivia.
- Argentine crested rat ( Ctenomys argentinus ) lives in the north-central part of Argentina (Provinces Formosa, Chaco, Santiago del Estero and Santa Fe).
- Southern crested rat or dune crested rat ( Ctenomys australis ) occurs in eastern Argentina (province of Buenos Aires).
- Azara crested rat ( Ctenomys azarae ) is native to central Argentina (provinces of Córdoba and La Pampa).
- Cordoba crested rat or mountain crested rat ( Ctenomys bergi ) lives only in the southwest of the Argentine province of Córdoba.
- Two-colored crested rat ( Ctenomys bicolor ) lives only in central Brazil.
- Ctenomys bidaui occurs only in the Argentine province of Chubut near the Valdés peninsula .
- Bolivia crested rat ( Ctenomys boliviensis ) inhabits central Bolivia, southwest Brazil (Mato Grosso), western Paraguay and northern Argentina (Formosa).
- Bonetto crested rat ( Ctenomys bonettoi ) is only known from the southeast of the Argentine province of Chaco.
- Brazilian crested rat ( Ctenomys brasiliensis ) inhabits eastern Brazil.
- Budin's crested rat ( Ctenomys budini ) is native to Jujuy, Argentina.
- Colburn crested rat ( Ctenomys colburni ) lives in the west of the Argentine province of Santa Cruz.
- The puntilla crested rat ( Ctenomys coludo ) lives in the province of Catamarca (Argentina).
- Conover crested rat or Chaco crested rat ( Ctenomys conoveri ) is native to the Chaco region of southeastern Bolivia, Paraguay, and northeastern Argentina.
- Ctenomys contrerasi occurs in the Argentine province of Chubut.
- D'Orbigny's crested rat ( Ctenomys dorbignyi ) occurs only in the Argentine province of Corrientes.
- Striped crested rat ( Ctenomys dorsalis ) lives in Paraguay west of the Paraguay River.
- Emilio Budin's crested rat ( Ctenomys emilianus ) lives in a small area of sand dunes in the Neuquén province.
- Erika crested rat ( Ctenomys erikacuellarae ) occurs in the southern center of Bolivia.
- Famatina crested rat ( Ctenomys famosus ) is native to the Argentine province of Rioja.
- Flamarion crested rat ( Ctenomys flamarioni ) occurs only in the Brazilian state of Rio Grande do Sul and is threatened by urban sprawl.
- Foch crested rat ( Ctenomys fochi ) lives in the province of Catamarca (Argentina).
- Lago Blanco crested rat ( Ctenomys fodax ) lives in the southern Argentine province of Chubut.
- Reddish comb rat or forest comb rat ( Ctenomys frater ) lives in southwestern Bolivia at altitudes of up to 4,300 meters.
- Yellow-brown comb rat or long-tailed comb rat ( Ctenomys fulvus ) is native to mountainous regions in northern Chile in the area of the Atacama Desert .
- Goodfellow crested rat ( Ctenomys goodfellowi ) lives in the province of Santa Cruz in southeastern Bolivia.
- Haig crested rat or Patagonian crested rat ( Ctenomys haigi ) occurs in the southern Argentine provinces of Chubut and Rio Negro.
- Ibicui crested rat ( Ctenomys ibicuiensis ) occurs in southern Brazil.
- The San Juan Comb rat ( Ctenomys johannis ) lives only in the south of the province of San Juan (Argentina).
- The jujuy crested rat ( Ctenomys juris ) is native to the southeast of the Argentine province of Jujuy.
- Knight crested rat or Catamarca crested rat ( Ctenomys knighti ) inhabits mountainous countries in western Argentina.
- Lami crested rat ( Ctenomys lami ) lives in the southern Brazilian state of Rio Grande do Sul.
- The spotted comb rat or yellow-brown comb rat ( Ctenomys latro ) is native to northwestern Argentina (provinces of Tucumán and Salta).
- Lessa crested rat ( Ctenomys lessai ) occurs in central Bolivia.
- White-toothed comb rat ( Ctenomys leucodon ) lives around Lake Titicaca in eastern Peru and western Bolivia.
- Lewis crested rat ( Ctenomys lewisi ) lives in southern Bolivia.
- Magellanic Comb rat ( Ctenomys magellanicus ) lives in the extreme south of Chile and Argentina, including the island of Tierra del Fuego. This species is endangered according to the IUCN.
- Maria Farelli crested rat ( Ctenomys mariafarelli ) in Bolivia in the northeast of Vallegrande.
- Maule crested rat ( Ctenomys maulinus ) is native to Chile (between the regions Maule and Araucania) and the neighboring Argentine province of Neuquén.
- Mendoza crested rat ( Ctenomys mendocinus ) inhabits the slopes of the Andes in western Argentina.
- Dwarf comb rat or little comb rat ( Ctenomys minutus ) lives in eastern Bolivia and southern Brazil.
- Natterer's comb rat ( Ctenomys nattereri ) lives in eastern Bolivia.
- Secret comb rat ( Ctenomys occultus ) occurs in northwestern Argentina (Tucumán province and neighboring areas).
- Highland crested rat or Andean crested rat ( Ctenomys opimus ) is native to the Puna region in northwest Argentina, southwest Bolivia, southern Peru and northern Chile.
- Osvaldo Reig Combed Rat ( Ctenomys osvaldoreigi ) is only known from the Argentine province of Córdoba.
- Paraguayan crested rat ( Ctenomys paraguayensis ) lives in the southeast of Paraguay.
- Pearson's comb rat ( Ctenomys pearsoni ) lives in Uruguay.
- Goya crested rat or Corrientes crested rat ( Ctenomys perrensi ) occurs only in the northeast Argentine province of Corrientes.
- Peruvian crested rat ( Ctenomys peruanus ) inhabits the Altiplano in the extreme south of Peru.
- Pilar crested rat ( Ctenomys pilarensis ) is native to eastern Paraguay.
- San Luis Comb rat or Middle Comb rat ( Ctenomys pontifex ) lives in western Argentina (provinces of San Luis and Mendoza).
- Porteous comb rat or cinnamon-colored comb rat ( Ctenomys porteousi ) inhabits the eastern Argentine provinces of Buenos Aires and La Pampa.
- Pundt crested rat ( Ctenomys pundti ) is common in the Argentine provinces of Córdoba and San Luis.
- Río Negro crested rat ( Ctenomys rionegrensis ) lives in eastern Argentina and Uruguay.
- Roig- comb rat ( Ctenomys roigi ) occurs only in Corrientes (Argentina).
- Rondônia crested rat ( Ctenomys rondoni ) occurs in southwestern Brazil.
- Pascual crested rat ( Ctenomys rosendopascuali ) occurs in Argentina.
- Salta crested rat ( Ctenomys saltarius ) is native to northern Argentina (Salta and Jujuy).
- Scaglia crested rat ( Ctenomys scagliai ) is only known from the province of Tucumán (northern Argentina).
- The silk comb rat ( Ctenomys sericeus ) lives in the southern Argentine provinces of Santa Cruz, Chubut and Río Negro.
- The social crested rat or colony crested rat ( Ctenomys sociabilis ) occurs only in the province of Meuquén (Argentina).
- Steinbach Comb rat ( Ctenomys steinbachi ) lives in the Santa Cruz province in Bolivia.
- Forest crested rat ( Ctenomys sylvanus ) is common in northwestern Argentina (Jujuy and Salta provinces).
- Talas crested rat or La-plate crested rat ( Ctenomys talarum ) inhabits the coastal region of the Argentine province of Buenos Aires.
- Ctenomys thalesi occurs only in the northeast of the Argentine province of Chubut.
- Collared crested rat ( Ctenomys torquatus ) occurs in Uruguay, northeast Argentina and southern Brazil.
- Robust comb rat ( Ctenomys tuconax ) is native to the Argentine province of Tucumán.
- Tucumán crested rat ( Ctenomys tucumanus ) lives in northwestern Argentina.
- Sierra del Tontal crested rat ( Ctenomys tulduco ) occurs only in the province of San Juan (Argentina).
- Guanacache comb rat or guaymalién comb rat ( Ctenomys validus ) lives in the Argentine province of Mendoza.
- Vipos crested rat or Trancas crested rat ( Ctenomys viperinus ) is native to the north of the province of Tucumán (Argentina).
- Yates crested rat ( Ctenomys yatesi ) occurs in southeastern Bolivia.
- Yolanda crested rat or Santa Fe crested rat ( Ctenomys yolandae ) lives in the Argentine province of Santa Fe.
On the basis of molecular biological studies, several kin groups were identified within the genus, with 8 main groups being described: boliviensis , frater , mendocinus , opimus , magellanicus , talarum , torquatus , and tucumanus . With the species that gives it its name, these include one to six species, each representing a species complex. However, not all species of the genus were included in this study from 2011.
Comb rats and humans
In some places, crested rats invade fields and plantations, which is why they are viewed as a nuisance. Their burrows, just below the surface, also cause horses and other animals to break in and break their legs in the process. For these reasons, some species are sometimes intensely hunted. In some heavily agricultural regions they have disappeared, and there is usually no data for precise information on the degree of risk.
literature
- TRO Freitas: Family Ctenomyidae In: Don E. Wilson, TE Lacher, Jr., Russell A. Mittermeier (editor): Handbook of the Mammals of the World: Lagomorphs and Rodents 1. (HMW, Volume 6) Lynx Edicions, Barcelona 2016 , P. 498 ff. ISBN 978-84-941892-3-4 .
- Ronald M. Nowak: Walker's Mammals of the World. 2 volumes. 6th edition. Johns Hopkins University Press, Baltimore MD u. a. 1999, ISBN 0-8018-5789-9 .
- Don E. Wilson , DeeAnn M. Reeder (Eds.): Mammal Species of the World. A taxonomic and geographic Reference. 2 volumes. 3. Edition. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 .
Individual evidence
- ↑ a b c d e f "Morphological Aspects." In: TRO Freitas: Family Ctenomyidae In: Don E. Wilson, TE Lacher, Jr., Russell A. Mittermeier (editor): Handbook of the Mammals of the World: Lagomorphs and Rodents 1. (HMW, Volume 6) Lynx Edicions, Barcelona 2016, pp. 502-503. ISBN 978-84-941892-3-4 .
- ↑ a b c d e f “Systematics.” In: TRO Freitas: Family Ctenomyidae In: Don E. Wilson, TE Lacher, Jr., Russell A. Mittermeier (editor): Handbook of the Mammals of the World: Lagomorphs and Rodents 1. (HMW, Volume 6) Lynx Edicions, Barcelona 2016, pp. 498-502. ISBN 978-84-941892-3-4 .
- ^ Nahuel A. De Santi, Diego H. Verzi, A. Itatí Olivares, Pedro Piñero, Cecilia C. Morgan, Matías E. Medina, Diego E. Rivero, Eduardo P. Tonni: A new peculiar species of the subterranean rodent Ctenomys ( Rodentia, Ctenomyidae) from the Holocene of central Argentina. In: Journal of South American Earth Sciences, SAMES 102499, 2020 doi : 10.1016 / j.jsames.2020.102499
- ↑ a b T.RO Freitas: Family Ctenomyidae In: Don E. Wilson, TE Lacher, Jr., Russell A. Mittermeier (editor): Handbook of the Mammals of the World: Lagomorphs and Rodents 1. (HMW, Volume 6) Lynx Edicions, Barcelona 2016, p. 498 ff. ISBN 978-84-941892-3-4 .
- ↑ a b c d Scott L. Gardner et al. 2014. New Species of Ctenomys Blainville 1826 (Rodentia: Ctenomyidae) from the Lowlands and Central Valleys of Bolivia. Special Publications of the Museum of Texas Tech University, no.62
- ↑ a b c Pablo Teta, Guillermo D'Elía: Uncovering the Species Diversity of Subterranean Rodents at the End of the World: Three New Species of Patagonian Tuco-tucos (Rodentia, Hystricomorpha, Ctenomys). PeerJ. 8: e9259, 2020. doi : 10.7717 / peerj.9259
- ↑ Andrés Parada, Guillermo D'Elía, Claudio J. Bidau, Enrique P. Lessa: Species groups and the evolutionary diversification of tuco-tucos, genus Ctenomys (Rodentia: Ctenomyidae). Journal of Mammalogy 92 (3), June 9, 2011; Pp. 671-682. doi : 10.1644 / 10-MAMM-A-121.1
Web links
- Endangerment level of the individual species in the IUCN Red List of Threatened Species .