Chaetodipus spinatus
| Spiny Pocket Mouse
(Chaetodipus spinatus) | |
|---|---|
| Range | |
 | |
| Taxonomic classification | |
| Order: | Rodentia |
| Suborder: | Supramyomorpha |
| Infraorder: | Castorimorphi |
| Superfamily: | Geomyoidea |
| Family: | Heteromyidae |
| Subfamily: | Perognathinae |
| Genus: | Chaetodipus |
| Binomial details | |
| Chaetodipus spinatus (C. H. Merriam, 1889) | |
| Other resources | |
| Full taxonomic details at MDD | |
The Spiny Pocket Mouse (Chaetodipus spinatus) is a medium- to large-sized pocket mouse found on rocky and gravelly soils and rocky slopes. It ranges from southern California to the southern tip of Baja California Sur, Mexico.
Description
From Lackey (1991): "The length of the hind foot is 27% of length of head and body, and the length of the tail is 126% of length of head and body (Hatt, 1932). The pelage of C. spinatus is hispid, with large and prominent spines on the rump, scattered on the flanks and sides, and often extending to the shoulders. Upper parts are drab brown, with the hairs plumbeous basally, pale tan subterminally, and black-tipped. The sides and the orbital region are slightly paler than the back, the lateral line is faint or absent, and the underparts are buffy white. The ears are small and orbicular, dusky, and the subauricular spot is small. The tail is moderately long; hair is brown above, whitish below, and crested. The spines are white with dusky tips, except on the sides where the tips are white (Osgood, 1900). Guard hairs are characterized by a flattened, imbricate scale pattern, and by a dorsal trough that varies among the subspecies in depth and width. C. spinatus has the longest and widest guard hairs of any of the eight species of Chaetodipus examined; the length (in mm) ranged from 9.7 to 10.0, and the width from 0.12 to 0.14."
From Jameson & Peeters (2004): "A rather large, yellow brown pocket mouse with a bicolored, crested tail and whitish, spiny hairs on the rump. The heel of the hind foot is naked. The ears are rather small (5—7 mm)."
Museum specimens
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Holotype: USNM 186516. Chaetodipus spinatus spinatus. Adult male. Twenty-five miles (40 km) below The Needles, Lower Colorado River, San Bernardino County, California. Collected 23 March 1889. Dorsal view. -
Holotype: USNM 186516. Chaetodipus spinatus spinatus. Adult male. Twenty-five miles (40 km) below The Needles, Lower Colorado River, San Bernardino County, California. Collected 23 March 1889. Ventral.
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 |
|---|---|---|---|---|---|---|
| California | Jameson & Peeters (2004) | 164–225 | 89–128 | 20–28 | 19–29 | |
| not reported | Ceballos (editor, 2014) | 85–89 | 107–124 | 25–26 | 9–10 | 20–22 |
| rangewide | Lackey (1991) | males: 199 (n=20); females: 198 (n=20) | males: 114 (n=20); females: 115 (n=20) | males: 24 (n=20); females: 24 (n=20) | males: 10 (n=20); females: 10 (n=20) |
Skull
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Holotype: USNM 186516. Chaetodipus spinatus spinatus. Adult male. Twenty-five miles (40 km) below The Needles, Lower Colorado River, San Bernardino County, California. Collected 23 March 1889. Dorsal view of the skull. -
Holotype: USNM 186516. Chaetodipus spinatus spinatus. Adult male. Twenty-five miles (40 km) below The Needles, Lower Colorado River, San Bernardino County, California. Collected 23 March 1889. Ventral view of the skull. -
Holotype: USNM 186516. Chaetodipus spinatus spinatus. Adult male. Twenty-five miles (40 km) below The Needles, Lower Colorado River, San Bernardino County, California. Collected 23 March 1889. Lateral view of the skull. -
Holotype: USNM 186516. Chaetodipus spinatus spinatus. Adult male. Twenty-five miles (40 km) below The Needles, Lower Colorado River, San Bernardino County, California. Collected 23 March 1889. Dorsal view of the mandible. -
Holotype: USNM 186516. Chaetodipus spinatus spinatus. Adult male. Twenty-five miles (40 km) below The Needles, Lower Colorado River, San Bernardino County, California. Collected 23 March 1889. Lateral view of the left mandible. -
Holotype: USNM 186516. Chaetodipus spinatus spinatus. Adult male. Twenty-five miles (40 km) below The Needles, Lower Colorado River, San Bernardino County, California. Collected 23 March 1889. Upper molars. -
Holotype: USNM 186516. Chaetodipus spinatus spinatus. Adult male. Twenty-five miles (40 km) below The Needles, Lower Colorado River, San Bernardino County, California. Collected 23 March 1889. Lower molars.
Similar species
In the USA, Chaetodipus spinatus is sympatric with the following species of pocket mice: California Pocket Mouse (Chaetodipus californicus), San Diego Pocket Mouse (Chaetodipus fallax), Long-tailed Pocket Mouse (Chaetodipus formosus), Desert Pocket Mouse (Chaetodipus penicillatus), Peninsular Pocket Mouse (Chaetodipus rudinoris), and Little Pocket Mouse (Perognathus longimembris). The presence of pronounced rump spines distinguishes C. spinatus from pocket mice in the genus Perognathus and from the Long-tailed Pocket Mouse (Chaetodipus formosus) and the Desert Pocket Mouse (Chaetodipus penicillatus) (Lackey, 1991). The California Pocket Mouse (Chaetodipus californicus) and the San Diego Pocket Mouse (Chaetodipus fallax) also have pronounced rump spines, but C.spinatus is distinguished by its lack of a well-marked lateral line (Hall, 1981; Lackey, 1991).
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Spiny Pocket Mouse (Chaetodipus spinatus) observed by Charles A. Drost and Jan Hart, USGS. The lateral line is faint or absent in this species. -
California Pocket Mouse (Chaetodipus californicus). Arrow points to the well-defined, buff-colored lateral line. -
San Diego Pocket Mouse (Chaetodipus fallax) observed in Riverside County, California, by Caleb Villar. The lateral line is pinkish buff in this species.
References
Ceballos G, editor. 2014. Mammals of Mexico. Baltimore (MD, USA): Johns Hopkins University Press.
Hall ER. 1981. The mammals of North America. 2 vols. John Wiley and Sons, New York
Hatt RT. 1932. The vertebral columns of ricochetal rodents. Bulletin of the American Museum of Natural History 63:599-738.
Jameson EW, Peeters HJ. 2004. Mammals of California (No. 66). Berkeley (CA, USA): University of California Press.
Lackey JA. 1991. Chaetodipus spinatus. Mammalian species (385): 1-4.
Merriam CH. 1889. Revision of the North American pocket mice. North American Fauna 1:1-29.
Osgood WH. 1900. Revision of the pocket mice of the genus Perognathus. North American Fauna 18:1-73.