Onychomys torridus
| Southern Grasshopper Mouse
(Onychomys torridus) | |
|---|---|
| Range | |
 | |
| Taxonomic classification | |
| Order: | Rodentia |
| Suborder: | Supramyomorpha |
| Infraorder: | Myomorphi |
| Superfamily: | Muroidea |
| Family: | Cricetidae |
| Subfamily: | Neotominae |
| Tribe: | Onychomyini |
| Genus: | Onychomys |
| Binomial details | |
| Onychomys torridus (Coues, 1874) | |
| Other resources | |
| Full taxonomic details at MDD | |
The Southern Grasshopper Mouse (Onychomys torridus) is a short-tailed, stocky mouse found in low, arid, scrub and semiscrub vegetation of deserts in the western United States and northwestern Mexico.
Description
From McCarty (1975): "O. torridus has forefeet with five plantar tubercles, and hindfeet with four. The soles of feet are covered with fur from heel to beginning of tubercles. The pelage is sharply bicolored, with upper parts grayish to pinkish cinnamon, underparts white and distinctly separated from upper parts. The nasals are wedge-shaped, interorbital constriction narrow, zygomatic plate narrow and straight anteriorly. The length of baculum is 3.9 to 6.5 mm, width at base 0.4 to 0.9 mm. Total body length is 120 to 163 mm. The tail is short, relatively thick, and distally white."
Museum type specimens
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Holotype: USNM 60174. Onychomys torridus torridus Adult female. Left bank of the Colorado River, at Monument 204, Mexican Boundary Line, Yuma County, Arizona. Collected 27 March 1894. -
Holotype: USNM 60174. Onychomys torridus torridus Adult female. Left bank of the Colorado River, at Monument 204, Mexican Boundary Line, Yuma County, Arizona. Collected 27 March 1894.
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 |
|---|---|---|---|---|---|---|
| Arizona (Gila, Pinal, Graham cos.) | Hoffmeister (1986) | 136–165 (n=29) | 47–60 (n=29) | 20–23 (n=29) | 16–20 (n=29) | |
| Arizona (Mohave Co., vic. Pakoon Springs and Lower Pigeon Spring) | Hoffmeister (1986) | 132–144 (n=23) | 45–49 (n=23) | 19–20 (n=23) | 15–17 (n=23) | |
| Arizona (Pima Co., vic. Baboquivari Mtns.) | Hoffmeister (1986) | 135–157 (n=20) | 48–58 (n=20) | 20–24 (n=20) | 16–20 (n=20) | |
| California | Jameson & Peeters (2004) | 120–165 | 39–52 | 18–20 | 11–17 | 20–26 |
Skull
From Hoffmeister (1986) for members of the genus Onychomys: "skull presents a unique combination of characters including relatively broad braincase, weak zygomatic arches that flare far laterally, broad across anterior roots of the zygoma, and broad rostrum with wedge-shaped nasals; coronoid process of mandible ascends more dorsally than does condyloid process; cheek teeth with labial and lingual cusps about equal height, mesoloph always lacking in upper teeth, M3/3 peglike, transverse valleys extend entirely across cheek teeth..."
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Holotype: USNM 60174. Onychomys torridus torridus Adult female. Left bank of the Colorado River, at Monument 204, Mexican Boundary Line, Yuma County, Arizona. Collected 27 March 1894. Dorsal view of the skull. The left zygomatic arch is broken. -
Holotype: USNM 60174. Onychomys torridus torridus Adult female. Left bank of the Colorado River, at Monument 204, Mexican Boundary Line, Yuma County, Arizona. Collected 27 March 1894. Ventral view of the mandible. -
Holotype: USNM 186476. Onychomys torridus longicaudus. Adult male. Saint George, Washington County, Utah. Collected 4 January 1889. Lateral view of the skull. -
Holotype: USNM 60174. Onychomys torridus torridus Adult female. Left bank of the Colorado River, at Monument 204, Mexican Boundary Line, Yuma County, Arizona. Collected 27 March 1894. Dorsal view of the mandible. -
Holotype: USNM 60174. Onychomys torridus torridus Adult female. Left bank of the Colorado River, at Monument 204, Mexican Boundary Line, Yuma County, Arizona. Collected 27 March 1894. Lateral view of the mandible. -
Holotype: USNM 60174. Onychomys torridus torridus Adult female. Left bank of the Colorado River, at Monument 204, Mexican Boundary Line, Yuma County, Arizona. Collected 27 March 1894. Upper molars. -
Holotype: USNM 60174. Onychomys torridus torridus Adult female. Left bank of the Colorado River, at Monument 204, Mexican Boundary Line, Yuma County, Arizona. Collected 27 March 1894. Lower molars.
Calls
The following call was provided by the Pasch Lab at the University of Arizona. For details regarding vocal production and vocal divergence in grasshopper mice, see Campbell et al. (2019).
Similar species
1. Total length 130 to 190 mm; tail usually less than half of body length (31 to 57%); maxillary toothrow long (3.8 to 4.8 mm); length of mandible usually more than 14 mm... O. leucogaster. 2. Total length 120 to 163 mm; tail usually more than half of body length (48 to 56%); maxillary toothrow short (3.3 to 4.0 mm); length of mandible usually less than 14 mm...... O. torridus.
From McCarty (1975): "O. torridus differs from O. leucogaster as noted in the key above, and as follows: mandible shorter (12.5 to 14.6 mm and 13.7 to 17.3 mm, respectively), zygomatic breadth narrower (11.9 to 13.7 mm and 12.6 to 17.3 mm, respectively), and smaller braincase (11.0 to 12.3 mm and 11.9 to 13.7 mm in width, respectively."
From Hoffmeister (1986): “O. leucogaster differs from O. torridus in numerous features, all of which are not obvious without careful examination and need to be used in combination. These include: tail less than half the body length, toothrow long, length of M1 usually less than half of the entire toothrow, M3 longer than wide, skull longer and wider (if condylobasal or greatest length is plotted against breadth, there is little or no overlap), baculum longer and bladelike rather than short and thin. If the fur on the underparts is white to the base, the animal is O. leucogaster, although some specimens do have the fur plumbeous as the base as in O. torridus.
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Southern Grasshopper Mouse (Onychomys torridus) -
Northern Grasshopper Mouse (Onychomys leucogaster). Note that this is an old, gray individual. -
Southern Grasshopper Mouse (Onychomys torridus) -
Northern Grasshopper Mouse (Onychomys leucogaster). Note that this is an old, gray individual.
References
Campbell P, Arévalo L, Martin H, Chen C, Sun S, Rowe AH, Webster MS, Searle JB, Pasch B. 2019. Vocal divergence is concordant with genomic evidence for strong reproductive isolation in grasshopper mice (Onychomys). Ecology and Evolution (9):12886-12896. https://doi.org/10.1002/ece3.5770
Coues E. 1874-12-15. Synopsis of the Muridae of North America. Proceedings of the Academy of Natural Sciences of Philadelphia 26(3):173-196.
Hoffmeister DF. 1986. Mammals of Arizona. Tucson (AZ, USA): University of Arizona Press.
Jameson EW, Peeters HJ. 2004. Mammals of California (No. 66). Berkeley (CA, USA): University of California Press.
McCarty R. 1975. Onychomys torridus. Mammalian Species (59):1-5.