A Pocket Gopher in the pre-Aztec city of Teotihuacán in Mexico. But which pocket gopher?

Seeing a rodent in the wild is always a good day—even if the taxonomy is complicated and I am confused.

A  pocket gopher was an animal we were looking out for when we were at the pre-Aztec archaeological site Teotihuacán near Mexico City last month. Lots of signs of their excavations near the entrance at the southern end of the site and eventually one was seen emerging from its burrow every couple of minutes to push earth out of the burrow and on to the soil heap. Pocket gophers can use their upper front incisors for digging because the mouth can be closed behind the teeth.

Pyramid of the Sun, Teotihuacán

Pocket Gophers are thus called because they have fur-lined cheek pouches that are used to stash food on their forays above ground. They belong to the all-American (in the proper, wide, sense of the word American) rodent family, Geomyidae.

The excavations of the pocket gophers can be seen in this area near the southern gate

The large teeth can be seen in this frame from my video

The taxonomy of pocket gophers is complicated. The current position, shown in the IUCN Red List, is that Teotihuacán is shown as being in the range of the Smoky Pocket Gopher (Cratogeomys fumosus) but not of Merriam’s Pocket Gopher (Cratogeomys merriami) even though specimens collected there in the past have been identified as belonging to one or the other of the two species. Thus modern photographs of the pocket gophers at Teotihuacán are captioned as Cratogeomys fumosus.

To complicate matters further Merriam’s Pocket Gopher was named for Clinton Hart Merriam (1855-1942) by Oldfield Thomas of the Natural History Museum in London in 1893 while the Smoky Pocket Gopher was named by Merriam himself in 1892.

A paper published in 2005 which showed the results of morphometric, chromosomal and mitochondrial DNA analysis, indicates that specimens, apparently accepted as C. merriami have been collected only about 15 miles to the south of Teotihuacán. Is there then still doubt as to the identity of the pocket gopher to be seen at that ancient site? A specimen held in the Museum of Vertebrate Zoology in the University of California was used in the morphological analysis of specimens C. merriami but not referred to specifically. Did it fit perfectly the criteria in the key to identification shown in the paper? Similarly, where does a specimen in the collection of the University of Kansas collected at Teotihuacán, labelled as C. fumosus and was used in the analysis in a 2004 paper fit in?

In my confusion I should end with the question: does anybody have definitive information on the identity of of the pocket gopher at Teotihuacán? Were we looking at the species named by Merriam or the one named for Merriam?

…I am not though confused as to the route taken from London to Mexico City. We flew over the Gulf of Mexico.

Hafner MS, Spradling TA, Light, JE, Hafner DJ, Demboski JR. 2004. Systematic revision of pocket gophers of the Cratageomys gymnurus species group. Journal of Mammalogy 85, 1170-1183.

Hafner MS, Light, JE, Hafner DJ, Brant SV, Spradling TA, Demastes JW. 2005. Cryptic species in the Mexican pocket gopher Cratageomys merriami. Journal of Mammalogy 86, 1095-1108.

Merriam, CH. 1892. Descriptions of nine new mammals collected by E. W. Nelson in the states of Colima and Jalisco, Mexico. Proceedings of the Biological Society of Washington 7,164-174.

Thomas O. 1893. On some of the larger species of Geomys. Annals and Magazine of Natural History. 6th Series. 12, 269-273.