It’s a Bird, It’s a Plane, It’s a Gopherus Species!

Desert tortoise Gopherus agassizii

Desert tortoise Gopherus agassizii

Hello again, Chelonian lovers! Things are quiet around here with the tortoises brumating, so I thought for this blog, we could have a chat about Gopherus species. Why not, right?

The desert tortoise Gopherus agassizii, aka Xerobates agassizii, aka Scaptochelys agassizii or Agassizii’s land tortoise, in some circles, is a keystone species of the Mojave and Sonoran deserts and the Sinaloa region of northwestern Mexico. It was first described in 1861 by American surgeon and naturalist James G. Cooper as a new genus and species. The genus Gopherus refers to burrowing land tortoises, and the specific epithet agassizii is in honor of French naturalist Jean Louis Agassiz. A member of the Testudines, it dates back to the Oligocene epoch, 33 to 24 million years ago, and is closely related to the extinct genus Stylemys or pillar tortoise. The Stylemys genus represents the first dry land tortoises of the Testudineum Order found in North America. The Gopherus genus is closely related to these pillar tortoises but differ in that Stylemys’ forelimbs were not adapted for burrowing, whereas burrowing is the Gopherus genus’ claim to fame.

The desert tortoise is one of five species belonging to the genus Gopherus: G. polyphemus (Gopher tortoise), G. flavomarginatus (Bolson tortoise), G. berlandieri (Texas desert tortoise), and, most recently distinguished, G. morafkai (Morafka’s desert tortoise). Though these five species are found in varying habitats throughout North America, from time to time a Gopherus species can be found outside of its range (usually through the pet trade or accidental “hitchhiking”), and knowledge of distinguishing characteristics is important due to differing husbandry requirements and regulations across state lines.

Though there is much literature describing the different characteristics of the Gopherus genus, it can still be tricky to distinguish what you are looking at when they are right in front of you, and that’s when the magic of genetic testing comes into play. We are lucky to have partnerships with institutions able to perform such tests for us. In fact, we recently had some of our tortoises’ genetic backgrounds tested to determine if they were from Nevada populations. And wouldn’t you know it, not one of the five samples sent out were from Nevada! Three were from northern Colorado (what!?), one from Arizona, and one from the central Mojave! These animals all came to us from pet owners no longer able to care for these animals. These results just go to show you how far a tortoise can travel from “home” with the help of well-meaning desert enthusiasts.

Larisa Gokool is a research associate at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post,
Do Tortoises Wear Shower Caps?

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