1a. Heel of each hind foot with 1 or 2 horny spades (Fig. 9) … 2
1b. Horny spades absent from hind feet … 4
2a. Heel of each hind foot with 1 horny spade (Fig. 9a); parotoid glands (Fig. 10) round and small; pupils of eyes vertical … Eastern Spadefoot
2b. Heel of each hind foot with 1 large and 1 small spade (Fig. 9b); parotoid glands (Fig. 10) oval and large; pupils of eyes horizontal or round; numerous warts on body … 3
3a. Dorsum with small spots that typically include 1 or 2 warts; venter usually profusely mottled with black; tibial warts distinctly larger than femoral warts … American Toad
3b. Dorsum with large spots that include 3 or more warts; venter pigment confined to a small spot on the chest; tibial warts not distinctly larger than femoral warts … Fowler’s Toad
4a. Fold of skin behind head; head less than one-fourth snout-vent length; tympanum absent … Eastern Narrow-mouthed Toad
4b. No fold of skin behind head; head approximately one-third of snout-vent length; tympanum present … 5
5a. Tips of toes expanded to form disc-like toe pads … 6
5b. Tips of toes not expanded to form disc-like toe pads … 12
6a. Toe pads small and inconspicuous, not wider than end of toe; snout-vent length less than 35 mm … 7
6b. Toe pads conspicuous, wider than end of toe; maximum snout-vent length 50 mm … 10
7a. Toes fully webbed; dorsum with numerous small warts; marking between eyes dark and triangle-shaped … Blanchard’s Cricket Frog
7b. Toes not webbed, or webbing restricted to a small flap of skin on each side of digit; dorsum without warts; marking between eyes absent … 8
8a. Body short and stout; lateral dark stripe passing through each eye and onto shoulder; a dark spot beneath each eye; front legs large and muscular … Illinois Chorus Frog
8b. Body flattened and elongate; lateral stripe passing through eye reaches beyond shoulder; no dark spot beneath eye; front legs not large and muscular. Dorsum with 3 distinct longitudinal stripes, each stripe as wide as the space between the stripes, or dorsum without longitudinal stripes or, if present, stripes one-half as wide as the space between them … Trilling Chorus Frogs
9a. Ground color of dorsum tan or pink, dorsum with distinct dark X mark … Spring Peeper
9b. Ground color of dorsum dark; dorsum without X mark … 10
10a. Dorsum green and without a star-shaped blotch; light spot under eye absent … Green Treefrog
10b. Dorsum variable in color, usually with a star-shaped blotch; light spot present under eye … 11
11a. Underside of thighs bright orange or yellow; snout-vent length to 60 mm … Gray Treefrog Complex
11b. Underside of thighs not bright orange or yellow; snout-vent length under 50 mm … Bird-voiced Treefrog
12a. Dorsolateral folds (Fig. 11) absent; tympanic fold well developed … American Bullfrog
12b. Pair of dorsolateral folds (Fig. 11) extending onto dorsum; tympanic fold inconspicuous … 13
13a. Dorsolateral folds (Fig. 11) terminating just beyond mid-dorsum … Green Frog
13b. Dorsolateral folds (Fig. 11) extending the length of the dorsum … 14
14a. Dark mask passing through eye and tympanum; dorsum without distinct spots, but may have dashes … Wood Frog
14b. No dark mask passing through eye and tympanum; dorsum with distinct spots … 15
15a. Jaws mottled; dorsal spots closely crowded together in a reticulated pattern … Crawfish Frog
15b. Jaws not mottled; dorsal spots not closely crowded … 16
16a. Dorsal spots square or rectangular and regularly arranged in 2 rows between the dorsolateral folds (Fig. 12a); concealed surfaces of thighs yellow … Pickerel Frog
16b. Dorsal spots irregular in shape and arrangement; concealed surfaces of thighs white … 17
17a. Dorsolateral folds wide and moderately raised; dorsal spots larger than eye and ringed in white or cream (Fig. 12b); snout usually with dark spot … Northern Leopard Frog
17b. Dorsolateral folds narrow and distinctly raised; dorsal spots on average smaller than eye and not ringed in white; snout with or without spot … 18
18a. Dorsolateral folds broken near groin and displaced toward midline (Fig. 12c); snout rounded, usually with a spot … Plains Leopard Frog
18b. Dorsolateral folds usually continuous, but if broken, broken sections never displaced toward midline (Fig. 12d); snout pointed, usually without a spot … Southern Leopard Frog
