Ictidomys
| Ictidomys | ||||||||||||
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Thirteen-striped squirrel ( Ictidomys tridecemlineatus ) |
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| Scientific name | ||||||||||||
| Ictidomys | ||||||||||||
| Allen , 1877 |
Ictidomys is a genus of real ground squirrels that is distributed in three species in North America.
features
The species of the genus are medium-sized ground squirrels and have a head-trunk length of about 26.5 to 31.3 centimeters. The tail is between 8 and 15 centimeters long, the tail length usually corresponds to between 50 and 70% of the body length. It is of medium length and bushy and fringed with light hair at the end. The ears are 6 to 12 millimeters in length and are therefore relatively small; the rear foot length is 35 to 46 millimeters. The species have a conspicuous coloration with stripes and spots on the back fur and are therefore easy to distinguish from other species. The back color is sandy to light brown and in all three types, clearly separated cream-white stripes and rows of spots from the ear over the back. These stripes are flanked by darker lines, the flanks of the animals are colored sand-colored to gray. The coat is usually short and smooth. The females of the Ictidomys species have four to six pairs of teats .
The skull is narrow with a slightly downwardly curved snout. The strong incisors are slightly pointing backwards (ophistodont). The comparatively small molars are separated from the incisors by a clearly elongated diastema . The brain skull is narrow, the tympanic cavities relatively small and compressed at the sides.
distribution
The genus Ictidomys is widespread in the grass steppes of central-western North America from southern Canada to Mexico, with the distribution areas of the individual species partially overlapping. The distribution area of the thirteen-lined squirrel stretches across the Great Plains from southern Canada, northeastern Utah and Ohio to Texas and New Mexico in the south. The Rio Grande ground squirrel occurs in the southern Great Plains from southeastern New Mexico through western Texas to northeastern Mexico. In the areas where the two species overlap, matings and natural hybridizations can occur, but these are locally limited and rare. The Mexican ground squirrel occurs in central Mexico.
The altitude distribution of the species is between 200 and 3,000 meters.
Way of life
The species of the genus live in similar habitats , especially in the area of sandy grass steppes ( prairie ) with bushes. Although they are mainly adapted to these habitats, all three species can also get by in anthropogenically modified landscapes and can be found, among other things, in the area of roads, in cemeteries, in small towns and on golf courses within their range; it is sometimes assumed that this has increased through human activities. They are omnivorous and feed primarily on insects and insect larvae, seeds, leaves and grasses.
Systematics
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Phylogenetic systematics of the Marmotini according to Herron et al. 2004
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Ictidomys is a genus of squirrels , where it is assigned to the ground squirrels (Xerinae) and therein the real ground squirrels (Xerini). The first scientific description was made by Joel Asaph Allen in 1877 with the thirteen-stripe croissant as a type. Then the species were assigned to the ground squirrel (genus Spermophilus ) together with other taxa that are now considered genera and treated as a subgenus.
In a molecular biological study, Ictidomys was confirmed as a monophyletic group in 2004 and newly described at the genus level. It probably forms the sister group of a clade consisting of the Franklin ground squirrel ( Poliocitellus franklinii ), the prairie dogs ( Cynomys ) and the genus Xerospermophilus, which is also again raised at the genus level . The representatives of Xerospermophilus were partially assigned to the Ictidomys species.
There are three types of the genus:
- Thirteen- lined squirrel ( Ictidomys tridecemlineatus ) on the prairie of the United States and Canada
- Mexican ground squirrel ( Ictidomys mexicanus ) in central Mexico
- Rio Grande Ground Squirrel ( Ictidomys parvidens ) in northeastern Mexico, New Mexico, and Texas
The name Ictidomys is derived from the Greek names for the weasel and the mouse , which translates as "weasel mice" and is intended to indicate the slender, weasel-like shape of these animals.
Hazard and protection
Both the thirteen-stripe squirrel, the Mexican ground squirrel and the Rio Grande ground squirrel are not endangered by the International Union for Conservation of Nature and Natural Resources (IUCN) due to their comparatively large distribution area and stable populations ("least concern") classified.
supporting documents
- ↑ a b c d e f g h i j k l Kristofer M. Helgen, F. Russell Cole, Lauren E. Helgen & Don E. Wilson: Generic revision in the Holarctic ground squirrel genus Spermophilus. Journal of Mammalogy, 90, pp. 270-305, 2009
- ↑ a b c Matthew D. Herron, Todd A. Castoe, Christopher L. Parkinson: Sciurid phylogeny and the paraphyly of holarctic ground squirrels (Spermophilus). Molecular Phylogenetics and Evolution 31, 2004; Pp. 1015-1030. ( doi : 10.1016 / j.ympev.2003.09.015 , full text , PMID 15120398 )
- ^ Richard W. Thorington Jr., John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 268-271. ISBN 978-1-4214-0469-1
- ↑ Ictidomys tridecemlineatus in the IUCN Red List of Threatened Species 2014.3. Listed by: AV Linzey, NatureServe (G. Hammerson), 2008. Retrieved May 12, 2015., Ictidomys mexicanus on the IUCN Red List of Threatened Species 2014.3. Posted by: AV Linzey, R. Timm, ST Álvarez-Castañeda, I. Castro-Arellano, T. Lacher, 2008. Accessed May 12, 2015.