[3] Until recent mitochondrial DNA evidence was revealed, the greater short-horned lizard was considered to be the same species as the pygmy short-horned lizard, but the two are now considered distinct, with the pygmy species occupying the northwest portion of the U.S. and, formerly, the extreme south of British Columbia (now extirpated from Canada).

[5] It has a "snub-nosed" side profile compared to the sleeker snouts of many lizards, and relatively short legs.

Yearlings, perhaps in an "experimental" phase, consume the lowest proportion of ants (60%), supplementing their diets with various arachnids, beetles and grubs, isopods,[6] terrestrial mollusks (snails, slugs)[6] and earthworms, as well as Lepidopterans and their caterpillars.

Overall, throughout their lives, pygmy short-horned lizards always consume ants, though total quantities of a particular prey species will vary seasonally.

Predators of P. douglassi include the long-nosed leopard lizard,[6] Stellar's jay,[6] northern shrikes,[6] coyotes, foxes, birds of prey, bobcats, and potentially larger, squamate-consuming snakes, such as kingsnakes.