Megascapheus bottae

Botta's Pocket Gopher
(*Megascapheus bottae*)
Botta's Pocket Gopher (Megascapheus bottae)
Range
Taxonomic classification
Order:	Rodentia
Suborder:	Supramyomorpha
Infraorder:	Castorimorphi
Superfamily:	Geomyoidea
Family:	Geomyidae
Subfamily:	Geomyinae
Tribe:	Thomomyini
Genus:	Megascapheus
Binomial details
	Megascapheus bottae (Eydoux & P. Gervais, 1836)
Other resources
	Full taxonomic details at MDD

The Botta's Pocket Gopher (Megascapheus bottae) is a medium-sized herbivorous rodent that is fossorial (lives in the ground). They are thick-bodied, have fur-lined cheek pouches, and their forefeet have prominent claws for digging. The taxonomy and distribution of pocket gophers has undergone much revision since the early 2000s with the aid of molecular tools, with some major changes happening in the 2020s. Several studies have importantly exposed cryptic diversity and putative new species within this group. Further studies will be needed to fully understand new species boundaries.

Warning! Range maps may be unreliable. Recent molecular analyses have led to significant changes in our understanding of the distribution of this species. The most recent published range of this species was by Álvarez-Castañeda (2024) in Mammals of North America-Volume 2: Systematics and Taxonomy; however, this is not a peer reviewed publication. That range map is based on earlier, peer-reviewed molecular analyses by Álvarez-Castañeda (2010), which lists the range of bottae as rest of California, north and west of the Colorado River." Based on Figure 2. in Álvarez-Castañeda (2010), the range of bottae should include southern Oregon, southern Idaho, California, Nevada, Utah, Colorado, northern Arizona, and northern New Mexico. The range discrepancy between Álvarez-Castañeda (2010) and Álvarez-Castañeda (2024) is substantial. Please let us know if you have information that supports or refutes the use of either published ranges.

Warning! The American Society of Mammalogists' Mammal Diversity Database states: "further research using more integrative taxonomic methods is needed to confirm this taxonomic arrangement." In essence, the statement emphasizes that while the existing taxonomic arrangement might be a starting point, a more thorough investigation using integrative taxonomy is needed to confirm or refine species boundaries and provide stronger evidence for species status.

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)	190–300		22–35	5–8	102–209
Colorado	Armstrong et al. (2010)	200–260	60–85	28–33	5–7	110–215

Skull

Holotype: USNM 58123. Megascapheus bottae bottae. Adult male. Los Banos, Merced County, California. Collected 1 January 1894. Dorsal view of the skull.
Holotype: USNM 58123. Megascapheus bottae bottae. Adult male. Los Banos, Merced County, California. Collected 1 January 1894. Ventral view of the skull.
Holotype: USNM 58123. Megascapheus bottae bottae. Adult male. Los Banos, Merced County, California. Collected 1 January 1894. Lateral view of the skull.
Holotype: USNM 58123. Megascapheus bottae bottae. Adult male. Los Banos, Merced County, California. Collected 1 January 1894. Dorsal view of the mandible.
Holotype: USNM 58123. Megascapheus bottae bottae. Adult male. Los Banos, Merced County, California. Collected 1 January 1894. Lateral view of the left mandible.

Taxonomic notes

Elevation of subgenera within genus Thomomys Wied-Neuwied, 1839

Genetic analyses (CytB and COI) by Álvarez-Castañeda and Segura-Trujillo (2025) found that the two subgenera within the genus Thomomys Wied-Neuwied, 1839 — Megascapheus and Thomomys — are genetically distinct. Morphological and genetic data support considering these differences sufficient at the genus level. The new name for Thomomys bottae (Eydoux & P. Gervais, 1836) is Megascapheus bottae (Eydoux & P. Gervais, 1836).

Previous molecular studies in Thomomys bottae

Recent studies have shown that there is significant variation and monophyletic groups (genetically distinct from other groups) contained within Thomomys bottae. The phylogeography of the Thomomys bottae-unbrinus complex in the United States and Mexico was assessed by Álvarez-Castañeda (2010), supporting at least eight monophyletic groups that can be considered phylogenetic species. However, the author stresses the need for an analysis of the nuclear DNA before these eight groups be recognized as different species. Unfortunately, there is no apparent diagnostic morphological differences among these groups which could otherwise make species delimitations easier. Álvarez-Castañeda (2010) states "wherein populations that are genetically distinct appear morphologically identical, pocket gophers display high levels of anatomical variation among populations within species."

More recently, Bradley et al. (2023) used DNA sequence data obtained from the mitochondrial cytochrome-b gene to assess variation at the subspecific and species level for pocket gophers occurring in Texas. The authors also used findings from "previous morphometric, allozymic, karyotypic, and DNA studies were combined with DNA sequence data generated herein to assemble the broadest possible dataset for providing a taxonomic synthesis". They found that some of the members (or subspecies) formerly included in Thomomys bottae should be recognized as distinct species. In Texas and parts of New Mexico, populations previously referred to as Thomomys bottae are now recognized as baileyi, connectens, ruidosae, fulvus

DNA sequencing has proven useful in defining species boundaries and in generating phylogenetic relationships at the species level, but the use of morphological characters in differentiating among species and subspecies has been difficult, if not impossible. Future molecular work may split this species further.

Thomomys bottae range based on Jones and Baxter (2004).
Thomomys bottae range based on molecular analyses by Belfiore et al (2008).
Distribution of the "Pacific group" based on Álvarez-Castañeda (2010), which contains three subclades and includes Thomomys bottae.
Distribution of Megascapheus bottae based on Álvarez-Castañeda (2024) Mammals of North America Volume 2, which is not a peer-reviewed publication. The range discrepancy between Álvarez-Castañeda (2010) and Álvarez-Castañeda (2024) is not addressed in the literature and it is unclear how the range map in Álvarez-Castañeda (2024) was decided.

Similar species

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References

Álvarez-Castañeda ST. 2010. Phylogenetic structure of the Thomomys bottae–umbrinus complex in North America. Molecular Phylogenetics and evolution 54(3): 671-679.

Álvarez-Castañeda ST. 2024. Mammals of North America-Volume 2: Systematics and Taxonomy (Vol. 2). Springer Nature.

Álvarez-Castañeda ST, Segura-Trujillo CA. 2025. Genus-level review of pocket gophers in the family Geomyidae. Therya 16(1): 41-75.

Belfiore NM, Liu L, Moritz C. 2008. Multilocus phylogenetics of a rapid radiation in the genus Thomomys (Rodentia: Geomyidae). Systematic Biology 57(2): 294-310.

Bradley RD, Pham AT, Rich KA, Roberts EK, Soniat TJ, Poehlein CM, Mills MN, Ballard M, Pitts RM, Lindsey LL, Halsey MK. 2023. Genetic identification of pocket gophers (Genera Cratogeomys, Geomys, and Thomomys) in Texas and surrounding areas. Museum of Texas Tech University. https://www.depts.ttu.edu/nsrl/publications/downloads/SP78.pdf

Eydoux JFT, Gervais P. 1836. Sur le genre Pæphagomys et quelques autres rongeurs qui l'avoisinent. Magasin de zoologie 6:17-24.

Jones CA, Baxter CN. 2004. Thomomys bottae. Mammalian species 2004(742): 1-14. https://doi.org/10.1644/742