Northern Spider Tortoise
(Pyxis a. brygooi)

Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Chelonia
Family: Testudines
Genus: Pyxis
Species: arachnoides
Subspecies: brygooi

This subspecies of spider tortoise is (as its name suggests) the northern most representative of the three subspecies. The key to identifying the three subspecies is to look at the plastron (bottom of the shell). In the Northern spider tortoise the plastron will have limited to zero movement in its anterior portion, and will have a uniform yellow color as well. The common spider tortoise will have a moveable anterior hinge, which enables it to close much like an Eastern box turtle (Terrapene c. carolina). It also has a uniform yellow plastron. The final subspecies, the Southern spider tortoise has a moveable anterior hinge and many dark blotches on its plastron. Overall, the Northern subspecies is the smallest of the three reaching a weight of only 300 grams and 4½ inches in length.

All three subspecies are endemic to the unique spiny forests of southwestern Madagascar, with major rivers separating them from one another. The rapid currents in these rivers are probably what initially created the separate populations, and through time as the populations remained apart, changes slowly took place and each became unique subspecies. Unfortunately, there is very little information about the natural history of this tortoise. From what little we do know, we can estimate this subspecies is quite likely threatened with extinction. Like many animals in Madagascar, the primary threats include habitat destruction and over collection for the pet trade.

Not only is the subspecies rare in the wild, but also in AZA institutions as well. Currently only a handful of zoos are working with them. Late in 2006, Knoxville Zoological Gardens became the first zoo to successfully hatch this subspecies in captivity. Knoxville Zoological Gardens currently maintains the AZA studbook and population management plan.

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