Xerospermophilus
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Round-tailed ground squirrel ( Xerospermophilus tereticaudus ) |
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| Scientific name | ||||||||||||
| Xerospermophilus | ||||||||||||
| Merriam , 1892 |
Xerospermophilus is a genus of real ground squirrels that is distributed in four species in North America . The animals live in arid desert and steppe areas in western North America from Mexico to California and South Dakota .
features
The species of the genus are small to medium-sized ground squirrels and have a head-torso length of about 21 to 32 centimeters. The tail is between 5.7 and 11.3 centimeters long, the tail length usually corresponds to between 40 and 60% of the body length. He is of medium length and thin. The ears are comparatively large with a length of 5 to 10 millimeters, the rear foot length is 31 to 46 millimeters. The back color is pale brown to bright red-brown. The Mojave ground squirrel and the round-tailed ground squirrel do not have any noticeable markings. The spotted ground squirrel and the Perote ground squirrel can have light spots, which is why historically they were often related to the Ictidomys species. In contrast to these, however, the spots in the Xerospermophilus species do not form rows of spots or stripes, and the animals also have a shorter tail and hairier soles. The coat is short and smooth. The females of the Callospermophilus species have five pairs of teats .
The skull is comparatively filigree and has a short, blunt to moderately long snout, which is not as strongly curved downwards as in the Ictidomys species. The skull is narrow, the tympanic cavity relatively large. The molars are medium-sized and brachyodontic . The incisors are pointing backwards (ophistodont), the gap between them is small.
distribution
The genus Xerospermophilus is distributed in North America from the southwestern United States to central Mexico. The range of the Perote ground squirrel is limited to the Mexican states of Veracruz and Puebla . The Mojave ground squirrel occurs only in the north of the Mojave Desert in southern California , while the round-tailed ground squirrel is common in deserts and steppes from southern Nevada to southeastern California and western Arizona as well as on the Baja California peninsula and Sonora in Mexico. In the area of overlap with the range of the Mojave ground squirrel, there is rare hybridization between the species in a narrow strip on the Mojave River . The spotted squirrel lives in a comparatively large area from northern Mexico to southern and western Texas , New Mexico and eastern and northwestern Arizona to the southwest of South Dakota .
Way of life
The species of the genus live mainly in dry desert and steppe areas, which is how they got their name. The round-tailed sandstone, for example, occurs predominantly in the area of sandy dunes and avoids stony and rocky habitats , the other species also prefer sandy areas. The distribution areas are characterized in part by extreme temperatures, which are well below freezing, especially in winter at night, and in which it is very hot during the day in summer. All species are omnivorous and feed mainly on seeds, leaves and other green parts of vegetation as well as insects, whereby they can specialize seasonally on particularly abundant food sources. The species live in burrows and are usually solitary, the round-tailed ground squirrel lives semi-colonial and the animals sometimes use the burrows together.
Systematics
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Phylogenetic system of the genus Xerospermophilus according to Fernández 2012
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Phylogenetic systematics of the Marmotini according to Herron et al. 2004
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Xerospermophilus is a genus of squirrels , where they are assigned to the ground squirrels (Xerinae) and therein the real ground squirrels (Xerini). The first scientific description was as a subgenus of the ground squirrel (species Spermophilus ) by Clinton Hart Merriam in 1892 with the Mojave ground squirrel as the type species. Together with other taxa considered as genera today , it was treated accordingly as a subgenus.
A molecular biological investigation confirmed Xerospermophilus 2004 as a monophyletic group . This was also identified as a sister group of the prairie dogs ( Cynomys ) and therefore newly described at the genus level. The taxon formed together with these is the Franklin ground squirrel ( Poliocitellus franklinii ) as a sister group.
There are four types of the genus:
- Mojave ground squirrel ( Xerospermophilus mohavensis ), California
- Round-tailed ground squirrel ( Xerospermophilus tereticaudus ), California, Arizona, Baja California, Sonora
- Spotted Ground Squirrel ( Xerospermophilus spilosoma ), northern Mexico, Texas, New Mexico , Arizona , Colorado , Kansas
- Perote ground squirrel ( Xerospermophilus perotensis ), Veracruz , Puebla
The Mojave ground squirrel and the round-tailed ground squirrel already belonged to the subgenus Xerospermophilus , but the Perote ground squirrel and the spotted ground squirrel were classified in the former subgenus Ictidomys , which is now also considered an independent genus.
In a phylogenetic study with a focus on the relationship of the Perote ground squirrel, the Mojave ground squirrel and the round-tailed ground squirrel as well as the Perote ground squirrel and the spotted ground squirrel were identified as sister taxa, which are compared within the genus Xerospermophilus .
The name Xerospermophilus is derived from the Greek words xeros for "dry", spermatos for "seed" and phileo for "love", which translates as "dry seed lover".
Hazard and protection
The International Union for Conservation of Nature and Natural Resources (IUCN) classifies both the spotted squirrel and the round-tailed squirrel as not endangered (“least concern”) due to their comparatively large distribution area and stable populations. The Mojave ground squirrel lives in an area of less than 20,000 km 2 and is classified as endangered ("vulnerable"), the Perote ground squirrel even as critically endangered ("endangered") due to its even smaller distribution area.
supporting documents
- ↑ a b c d e f g h i j 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 Jesús A. Fernández: Phylogenetics and biogeography of the microendemic rodent Xerospermophilus perotensis (Perote ground squirrel) in the Oriental Basin of Mexico. Journal of Mammalogy 93 (6), 2012; Pp. 1431-1439. doi : 10.1644 / 11-MAMM-A-409.1
- ↑ 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. 366-371. ISBN 978-1-4214-0469-1
- ^ Xerospermophilus ( Memento from April 22, 2016 in the Internet Archive ). In: 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 .
- ^ Ictidomys ( Memento from April 22, 2016 in the Internet Archive ). In: 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 .
- ↑ Xerospermophilus spilosoma in the IUCN Red List of Threatened Species 2014.3. Posted by: AV Linzey, R. Timm, ST Álvarez-Castañeda, I. Castro-Arellano, T. Lacher, 2008. Retrieved on May 28, 2015., Xerospermophilus tereticaudus in 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 28, 2015.
- ↑ Xerospermophilus mohavensis in the IUCN Red List of Threatened Species 2014.3. Posted by: DJ Hafner, NatureServe (G. Hammerson, DF Williams), 2008. Retrieved May 28, 2015.
- ↑ Xerospermophilus perotensis in the IUCN Red List of Threatened Species 2014.3. Posted by: ST Álvarez-Castañeda, I. Castro-Arellano, T. Lacher, E. Vázquez, 2008. Accessed May 28, 2015.
literature
- Richard W. Thorington Jr., John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 366-371. ISBN 978-1-4214-0469-1
