Microdipodops megacephalus
| Owyhee Kangaroo Mouse
(Microdipodops megacephalus) | |
|---|---|
| Range | |
 | |
| Taxonomic classification | |
| Order: | Rodentia |
| Suborder: | Supramyomorpha |
| Infraorder: | Castorimorphi |
| Superfamily: | Geomyoidea |
| Family: | Heteromyidae |
| Subfamily: | Dipodomyinae |
| Genus: | Microdipodops |
| Subgenus: | Microdipodops (subgenus) |
| Binomial details | |
| Microdipodops megacephalus C. H. Merriam, 1891 | |
| Other resources | |
| Full taxonomic details at MDD | |
Hafner et al. (2025) used genetic (karyology and nuclear and mitochondrial DNA sequencing) and phenetic (cranial morphometrics and pelage colorimetry) characters to examine differentiation within the genus Microdipodops. They found that the species referred to as Microdipodops megacephalus is actually composed of four morphologically cryptic but genetically distinct species: the Bonneville Kangaroo Mouse (Microdipodops albiventer), the Owyhee Kangaroo Mouse (Microdipodops megacephalus), the Oregon Kangaroo Mouse (Microdipodops oregonus), and the Nevada Kangaroo Mouse (Microdipodops polionotus). According to Hafner et al. (2025), the range of the Owyhee Kangaroo Mouse (Microdipodops megacephalus) is restricted to "the upland flats of the Owyhee Desert in extreme southwestern Idaho, remote southeastern Oregon, and north-central Nevada and adjoining foothills and bajadas."
Description
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Holotype: USNM 24417/31823. Microdipodops megacephalus megacephalus. Adult male. Halleck, East Humboldt Valley, Elko County, Nevada. Collected 23 October 1890. -
Holotype: USNM 24417/31823. Microdipodops megacephalus megacephalus. Adult male. Halleck, East Humboldt Valley, Elko County, Nevada. Collected 23 October 1890.
Distribution
From Hafner et al. (2025): "Known from the upland flats of the Owyhee Desert in extreme southwestern Idaho, remote southeastern Oregon, and north-central Nevada and adjoining foothills and bajadas. Elevational range approximately 1,433m (= 4,700ft.) from vicinity of Golconda and Izenhood in the Nevadan counties of Humboldt and Lander, respectively, to approximately 1,680m (= 5,512ft.) vicinity of Basque, Malheur County, Oregon. As presently understood, the distribution is roughly triangular with the Oregonian locality of Basque at its northern vertex and the Nevadan environs of Golconda and Halleck forming the western and eastern basal vertices, respectively. The distribution of M. megacephalus approaches those of its neighboring species at these southern vertices. Microdipodops megacephalus appears to be separated from that of M. oregonus by a series of northsouth trending mountains (including the Osgood Mountains, Etna Mountain, and the Sonoma Range) at approximately −117.45˚ longitude in the vicinity of Golconda. Molecular evidence from museum specimens collected near Halleck (i.e., Halleck, 3mi. W Halleck, and 5mi. W Halleck), shows the presence of individuals of both M. megacephalus and M. polionotus."
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 |
|---|---|---|---|---|---|---|
| Holotype USNM 24417 (Elko County, Nevada) | Smithsonian National Museum of Natural History | 151 | 83 | 24 |
Skull
From Jameson & Peeters (2004): "The incisive foramina are pointed, converging anteriorly and wider posteriorly."
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Holotype: USNM 24417/31823. Microdipodops megacephalus megacephalus. Adult male. Halleck, East Humboldt Valley, Elko County, Nevada. Collected 23 October 1890. Dorsal view of the skull. -
Holotype: USNM 24417/31823. Microdipodops megacephalus megacephalus. Adult male. Halleck, East Humboldt Valley, Elko County, Nevada. Collected 23 October 1890. Ventral view of the skull. -
Holotype: USNM 24417/31823. Microdipodops megacephalus megacephalus. Adult male. Halleck, East Humboldt Valley, Elko County, Nevada. Collected 23 October 1890. Lateral view of the skull. -
Holotype: USNM 24417/31823. Microdipodops megacephalus megacephalus. Adult male. Halleck, East Humboldt Valley, Elko County, Nevada. Collected 23 October 1890. Dorsal view of the mandible. -
Holotype: USNM 24417/31823. Microdipodops megacephalus megacephalus. Adult male. Halleck, East Humboldt Valley, Elko County, Nevada. Collected 23 October 1890. Lateral view of the left mandible.
Similar species
From O’Farrell & Blaustein (1974a): "The dark kangaroo mouse is brownish, blackish, or grayish above and the underparts are basally plumbeous and white-tipped, whereas M. pallidus is pale pinkish cinnamon above and the hair of underparts is white to the base. The distal half of the tail is usually darker than the back. The hind foot is slightly smaller (23 to 25 mm) than that of M. pallidus (> 25 mm}."
From O’Farrell & Blaustein (1974b): "Hall (1946) presented evidence that hybridization occurs between M. pallidus and M. megacephalus in Penoyer Valley, N of Groom Baldy, Lincoln Co., Nevada."
From Jameson & Peeters (2004): "This species is distinguished from the Pale Kangaroo Mouse (M. pallidus) by color and by a smaller hind foot."
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Holotype: USNM 24417/31823. Microdipodops megacephalus megacephalus. Adult male. Halleck, East Humboldt Valley, Elko County, Nevada. Collected 23 October 1890. -
Holotype: USNM 24417/31823. Microdipodops megacephalus megacephalus. Adult male. Halleck, East Humboldt Valley, Elko County, Nevada. Collected 23 October 1890. -
Holotype: USNM 210397. Microdipodops pallidus pallidus. Adult male. Clayton Valley, Esmeralda County, Nevada. Collected 19 October 1915. -
Holotype: USNM 210397. Microdipodops pallidus pallidus. Adult male. Clayton Valley, Esmeralda County, Nevada. Collected 19 October 1915.
References
Hall ER. 1946. Mammals of Nevada. Berkeley (CA, USA): University of California Press.
Hafner, JC, Upham NS, Gowen-Huang F, Light JE. 2025. Cryptic species and taxonomic revision of kangaroo mice, the rodent genus Microdipodops. Journal of Mammalogy 106(6): 1342-1371.
Jameson EW, Peeters HJ. 2004. Mammals of California (No. 66). Berkeley (CA, USA): University of California Press.
Merriam CH. 1891. Description of a New Genus and Species of Dwarf Kangaroo Rat from Nevada (Microdipodops megacephalus). North American Fauna 5: 116.
O’Farrell MJ, Blaustein AR. 1974a. Microdipodops megacephalus. Mammalian Species 46: 1-3.
O’Farrell MJ, Blaustein AR. 1974b. Microdipodops pallidus. Mammalian Species (47): 1-2.