| Colorado's Amphibians |
| by Lauren J. Livo |
| Evaluate the criteria below to identify a species. |
| 1a. | Adult with long tail, aquatic larvae with conspicuous gills on sides of head. | Ambystoma tigrinum Tiger salamander |
| 1b. | Adult lacking tail. | go to 2 |
| 2a. | Skin warty, prominent parotoid glands behind eyes. | go to 3 |
| 2b. | Skin relatively smooth, no parotoid glands. | go to 7 |
| 3a. | Light mid-dorsal stripe. | go to 4 |
| 3b. | No light mid-dorsal stripe. | go to 6 |
| 4a. | Large symmetrical dark blotches on back. | Bufo cognatus Great Plains toad |
| 4b. | Not as above. | go to 5 |
| 5a. | No cranial crests, usually above 8,000'. | Anaxyrus boreas boreas Boreal toad |
| 5b. | Cranial crests, usually below 7,000'. | Bufo woodhousii Woodhouse's toad |
| 6a. | Parotoid glands nearly circular, body tan or gray with red warts. | Bufo punctatus Red-spotted toad |
| 6b. | Body green with scattered dark spots. | Bufo debilis Green toad |
| 7a. | Head small with fold of skin behind eyes. | Gastrophryne olivacea Great Plains narrowmouth toad |
| 7b. | Not as above. | go to 8 |
| 8a. | Vertical pupils; rear feet each with single, hard dark 'spade'. | go to 9 |
| 8b. | Pupils and rear feet not as above. | go to 12 |
| 9a. | Boss between eyes. | go to 10 |
| 9b. | No boss between eyes. | go to 11 |
| 10a. | Boss hard, mostly eastern Colorado. | Spea bombifrons Plains spadefoot |
| 10b. | Boss pliable, western Colorado. | Spea intermontana Great Basin spadefoot |
| 11a. | Body greenish-yellow with dark blotches; snout-vent length may exceed 2.5 inches. | Scaphiopus couchii Couch's spadefoot |
| 11b. | Body gray or brown with dark spots; snout-vent length up to 2.5 inches. | Spea multiplicata New Mexico spadefoot |
| 12a. | Conspicuous dorsolateral folds. | go to 13 |
| 12b. | No dorsolateral folds. | go to 15 |
| 13a. | Dark mask through eye from snout to angle of jaw, usually light mid-dorsal stripe, north-central Colo. | Rana sylvatica Wood frog |
| 13b. | No mid-dorsal stripe, dark spots on body. | go to 14 |
| 14a. | Dorsolateral folds continuous from eye to groin, body green or brown. | Rana pipiens Northern leopard frog |
| 14b. | Dorsolateral folds broken and inset near groin, body always brown. | Rana blairi Plains leopard frog |
| 15a. | Toepads distinctly enlarged. | Hyla arenicolor Canyon treefrog |
| 15b. | Not as above. | go to 16 |
| 16a. | Fold of skin around top of eardrum; body size may exceed 7 inches. | Rana catesbeiana Bullfrog |
| 16b. | Maximum body size less than 1.5 inches. | go to 17 |
| 17a. | Stripe through eye from snout to groin, usually three stripes on back (may be spotted), little webbing on hind feet. | Pseudacris triseriata Chorus frog |
| 17b. | Triangular spot between eyes, extensive webbing on hind feet. | Acris crepitans Northern cricket frog |