Chaetodipus eremicus

Chihuahuan Desert Pocket Mouse
(*Chaetodipus eremicus*)
Chihuahuan Desert Pocket Mouse (Chaetodipus eremicus)
Range
Taxonomic classification
Order:	Rodentia
Suborder:	Supramyomorpha
Infraorder:	Castorimorphi
Superfamily:	Geomyoidea
Family:	Heteromyidae
Subfamily:	Perognathinae
Genus:	Chaetodipus
Binomial details
	Chaetodipus eremicus (Mearns, 1898)
Other resources
	Full taxonomic details at MDD

The Chihuahuan Desert Pocket Mouse (Chaetodipus eremicus) is a medium-sized pocket mouse foud in the Chihuahuan Desert of New Mexico, Texas, and northern Mexico.

Description

From Mantooth & Best (2005): Chaetodipus eremicus is a medium-sized pocket mouse with a long, heavily crested, tufted tail. Ventral pelage and tail, including tuft, are white. Pelage is coarse with numerous thin, elongate rump hairs (not spines) that are dark dorsally and light laterally. Dorsal pelage is buff and sprinkled with black, making this area appear brown or grayish. Pelage on sides resembles back and lateral lines are not present (Davis and Schmidly 1994; Yancey 1997)."

From Schmidly & Bradley (2016): "A medium-sized pocket mouse with long, heavily crested and tufted tail; pelage coarse but lacking spines on rump; sole of hind foot naked to heel; upperparts vinaceous buff finely sprinkled with black, imparting a grayish tone; sides like back; no lateral line; underparts and tail to tuft white."

Museum type specimens

Holotype: USNM 21052. Chaetodipus eremicus eremicus. Adult female. Fort Hancock, Hudspeth County, Texas. Collected 27 June 1893.
Holotype: USNM 21052. Chaetodipus eremicus eremicus. Adult female. Fort Hancock, Hudspeth County, Texas. Collected 27 June 1893.

External measurements

Length measurements are in millimeters (mm) and weight measurements are in grams (g), unless stated otherwise. If available, the sample size (n=) is provided. If a range is not provided and n= is not given, then the listed measurement represents an average.

Part of range	Reference	Total length	Tail length	Hindfoot length	Ear length	Mass
not reported	Ceballos (editor, 2014)	147–179	77–98	21–25	7–8	13–19
Texas	Schmidly & Bradley (2016)	205	109	25		15–23
Texas (Brewster County)	Manning et al. (1996); mass from Davis & Schmidly (1994)	174.8 (n=34)	93.4 (n=34)	21.8 (n=38)	7.8 (n=38)	15.0–23
Texas (Trans-Pecos region)	Wilkins & Schmidly (1979)	169.55 (n=74 males and 45 females)	92.61 (n=74 males and 45 females)	21.79 (n=74 males and 45 females)	7.38 (n=74 males and 45 females)

Color variation

This section shows some of the color variation present in Chaetodipus eremicus. The location is provided for reference only. The individual shown does not necessarily represent the only color variant within the local population.

NEON05G5N. Chaetodipus eremicus. Subadult male. Jornada Experimental Range, Dona Ana County. New Mexico. Collected 9 November 2021.
NEON05FZR. Chaetodipus eremicus. Subadult female. Jornada Experimental Range, Dona Ana County. New Mexico. Collected 11 October 2021.

Skull

From Mantooth and Best (2005): "Interparietal is not in contact with mastoid bullae and is separated by narrow projections of parietals and supraoccipitals (Davis and Schmidly 1994; Yancey 1997)."

Holotype: 21052/36094. Chaetodipus eremicus eremicus. Adult female. Fort Hancock, El Paso (Hudspeth) County, Texas. Collected 27 June 1893. Dorsal view of the skul.
Holotype: 21052/36094. Chaetodipus eremicus eremicus. Adult female. Fort Hancock, El Paso (Hudspeth) County, Texas. Collected 27 June 1893. Arrows identify the interorbital width. The interparietal bone is colored yellow.
Holotype: 21052/36094. Chaetodipus eremicus eremicus. Adult female. Fort Hancock, El Paso (Hudspeth) County, Texas. Collected 27 June 1893. Ventral view of the skull.
Holotype: 21052/36094. Chaetodipus eremicus eremicus. Adult female. Fort Hancock, El Paso (Hudspeth) County, Texas. Collected 27 June 1893. Lateral view of the skull.
Holotype: 21052/36094. Chaetodipus eremicus eremicus. Adult female. Fort Hancock, El Paso (Hudspeth) County, Texas. Collected 27 June 1893. Dorsal view of the mandible.
Holotype: 21052/36094. Chaetodipus eremicus eremicus. Adult female. Fort Hancock, El Paso (Hudspeth) County, Texas. Collected 27 June 1893. Lateral view of the left mandible.
Holotype: 21052/36094. Chaetodipus eremicus eremicus. Adult female. Fort Hancock, El Paso (Hudspeth) County, Texas. Collected 27 June 1893. Upper molars.
Holotype: 21052/36094. Chaetodipus eremicus eremicus. Adult female. Fort Hancock, El Paso (Hudspeth) County, Texas. Collected 27 June 1893. Upper molars.
Holotype: 21052/36094. Chaetodipus eremicus eremicus. The interparietal (in yellow) is not in contact with mastoid bullae and is separated by narrow projections of parietals (in green) and supraoccipitals (in blue). Black arrows point to the narrow projections of the supraoccipitals in blue. The narrow projections of the parietals are shown in green.

Similar species

In the USA, Chaetodipus eremicus is sympatric or near-sympatric with the following species of pocket mice: Bailey's Pocket Mouse (Chaetodipus baileyi), Highland Coarse-haired Pocket Mouse (Chaetodipus collis), Hispid Pocket Mouse (Chaetodipus hispidus), Rock Pocket Mouse (Chaetodipus intermedius), Desert Pocket Mouse (Chaetodipus penicillatus), Plains Pocket Mouse (Perognathus flavescens), Silky Pocket Mouse (Perognathus flavus), and Merriam's Pocket Mouse (Perognathus merriami).

Comparison with Chaetodipus baileyi

Chihuahuan Desert Pocket Mouse (Chaetodipus eremicus)
Bailey's Pocket Mouse (Chaetodipus baileyi)
Holotype: 21052/36094. Chaetodipus eremicus eremicus. Adult female. Arrows identify the interorbital width. The interparietal bone is colored yellow. The interorbital region is narrower than the width of the interparietal.
Holotype: 17838/24775. Chaetodipus baileyi baileyi. Arrows identify the interorbital width. The interparietal bone is colored yellow. The interorbital region is wider than width of the interparietal.

Comparison with Chaetodipus collis

The Highland Coarse-haired Pocket Mouse (Chaetodipus collis) is a rock-dwelling pocket mouse and the restriction to rocky situations will usually separate this species from C. eremicus (CMDBS, 2008). The Highland Coarse-haired Pocket Mouse (Chaetodipus collis) is generally larger than C. eremicus and has rump spines.

Chihuahuan Desert Pocket Mouse (Chaetodipus eremicus)
Highland Coarse-haired Pocket Mouse (Chaetodipus collis). The black arrow points to one of the many rump spines.

Comparison with Chaetodipus hispidus

Chaetodipus eremicus is not easily confused with the Hispid Pocket Mouse (Chaetodipus hispidus). Chaetodipus hispidus is a large pocket mouse with a tail that lacks a crest and tuft.

Chihuahuan Desert Pocket Mouse (Chaetodipus eremicus)
Hispid Pocket Mouse (Chaetodipus hispidus).
Holotype: 21052/36094. Chaetodipus eremicus eremicus. Adult female. Arrows identify the interorbital width. The interparietal bone is colored yellow. The interorbital region is narrower than the width of the interparietal.
Holotype: 186513. Chaetodipus hispidus paradoxus. Arrows identify the interorbital width. The interparietal bone is colored yellow.

Comparison with Chaetodipus intermedius

The Rock Pocket Mouse (Chaetodipus intermedius) is a rock-dwelling pocket mouse and the restriction to rocky situations will usually separate this species from C. eremicus (CMDBS, 2008). Chaetodipus eremicus is similar in size to C. intermedius. C. intermedius has rump spines, but these may be difficult to detect (CMDBS, 2008).

Chihuahuan Desert Pocket Mouse (Chaetodipus eremicus)
Rock Pocket Mouse (Chaetodipus intermedius)
Holotype: 21052/36094. Chaetodipus eremicus eremicus. Arrows identify the interorbital width. The interparietal bone is colored yellow. The interorbital region is narrower than the width of the interparietal.
Holotype: 203003. Chaetodipus intermedius phasma. Arrows identify the interorbital width. The interparietal bone is colored yellow. The interorbital region is narrower than the width of the interparietal (Hoffmeister, 1986).

Comparison with Chaetodipus penicillatus

Chihuahuan Desert Pocket Mouse (Chaetodipus eremicus)
Desert Pocket Mouse (Chaetodipus penicillatus)
Holotype: 21052/36094. Chaetodipus eremicus eremicus. Adult female. Arrows identify the interorbital width.
Holotype: 73881. Chaetodipus penicillatus angustirostris . Arrows identify the interorbital width. The interparietal bone is colored yellow.

Comparison with Perognathus species

In the USA, Chaetodipus eremicus is sympatric with the Plains Pocket Mouse (Perognathus flavescens), Silky Pocket Mouse (Perognathus flavus), and Merriam's Pocket Mouse (Perognathus merriami). However, these species are small pocket mice with smooth tails that lack crests or tufts and their ears lack a lobed antitragus. Additionally, all three Perognathus species have both a postauricular and subauricular spot around each ear.

Chihuahuan Desert Pocket Mouse (Chaetodipus eremicus)
Plains Pocket Mouse (Perognathus flavescens)
Silky Pocket Mouse (Perognathus flavus)
Merriam's Pocket Mouse (Perognathus merriami) observed in Mexico by Marco Zozaya. Image by Marco Zozaya.
Arrow points to the location of the postauricular patch of the Silky Pocket Mouse (Perognathus flavus).
Arrow points to the location of the subauricular patch of the Silky Pocket Mouse (Perognathus flavus).
Black arrow points to the lobed antitragus found in the Chihuahuan Desert Pocket Mouse (Chaetodipus eremicus). All members of the genus Chaetodipus have ears with a lobed antitragus, but this fleshy projection of the ear is found in only a few members of the genus Perognathus.

References

Bailey V. 1931. Mammals of New Mexico. North American Fauna 53. US Department of Agriculture, Bureau of Biological Survey.

Centennial Museum and Department of Biological Sciences (CMDBS). 2008. Heteromyidae—Pocket Mice and Kangaroo Rats, The University of Texas at El Paso. [accessed 20 July 2024]. http://museum2.utep.edu/mammalogy/taxa/heteromyidae.htm

Davis WB, Schmidly DJ. 1994. The mammals of Texas. Nongame and Urban Program. Texas Parks and Wildlife Department, Austin.

Mantooth SJ, Best TL. 2005. Chaetodipus eremicus. Mammalian Species 2005(768):1-3.

Schmidly DJ, Bradley RD. 2016. The mammals of Texas. Austin (TX, USA): University of Texas Press.

Wilkins KT, Schmidly DJ. 1979. Identification and distribution of three species of pocket mice (genus Perognathus) in Trans-Pecos Texas. The Southwestern Naturalist, 17-31.

Yancey FD. 1997. The Mammals of the Big Bend Ranch State Park, Texas. Special Publications Museum of Texas Tech University 39:1–210.