1a. Bony shell covered with leathery skin … 2
1b. Bony shell covered with large scutes (Fig. 13a) … 3
2a. Anterior edge of carapace with small tubercles or spines; interior of nostrils with horizontal projections (Fig. 14a) … Spiny Softshell
2b. Anterior edge of carapace smooth; interior of nostrils lack projections (Fig. 14b) … Smooth Softshell
3a. Plastron with 11 or more plates contacting at midline (Fig. 13b); tail short (less than one-half shell length) … 4
3b. Plastron with fewer than 11 plates contacting at midline (Fig. 15); tail long (greater than one-half shell length) … 5
4a. Carapace (usually) with 11 pairs of marginal scutes (Fig. 13a); plastron with fewer than 6 pairs of scutes (Fig. 13b) … 6
4b. Carapace (usually) with 12 pairs of marginal scutes (Fig. 13a); plastron with 6 pairs of scutes (Fig. 13b) … 8
5a. Carapace with a single row of marginal scutes and 3 low keels that disappear with age … Snapping Turtle
5b. Carapace with an extra row of scutes between marginals and pleural scutes 1-3 on each side (Fig. 16) and 3 prominent keels that do not disappear with age … Alligator Snapping Turtle
6a. Skin showing between plastral scutes; pectoral scutes square (Fig. 17a); a single poorly developed plastral hinge anteriorly … Eastern Musk Turtle
6b. Skin not showing between plastral scutes; pectoral scutes triangular (Fig. 17b); 2 well-developed plastral hinges … 7
7a. Marginals 8 and 9 are of approximately equal height (Fig. 18a) … Eastern Mud Turtle
7b. Marginal 9 much higher than 8 (Fig. 18b) … Yellow Mud Turtle
8a. Plastron hinged between pectoral and abdominal scutes … 9
8b. Plastron not hinged … 11
9a. Chin and throat bright yellow; upper jaw notched … Blanding’s Turtle
9b. Chin and throat not bright yellow; upper jaw hooked … 10
10a. Carapace and plastron with radiating yellow lines; peak of carapace flattened and lacking a keel … Ornate Box Turtle
10b. Carapace pattern variable; plastron lacking discrete pattern of light lines; peak of carapace dome-like with median keel … Eastern Box Turtle
11a. Carapace black with prominent yellow spots … Spotted Turtle
11b. Carapace variable, without prominent yellow spots … 12
12a. Marginal scutes or plastron marked with red … Painted Turtle
12b. Marginal scutes and plastron not marked with red … 13
13a. Head pattern posterior to the eye comprised only of longitudinal stripes extending onto neck … 14
13b. Head pattern posterior to the eye includes a spot or horizontally oriented stripe or bar in addition to longitudinal stripes … 15
14a. Prominent red or orange stripe behind the eye; plastron with single dark spot or smudge per scute (head striping may be obscure in old, dark males but some plastral spots typically remain) … Pond Slider
14b. All head stripes yellow; plastron with little or no pattern … River Cooter
15a. Yellowish spot or comma-shaped marking behind the eye; median keel of carapace low and lacking prominent knobs … Northern Map Turtle
15b. Conspicuous blotch, crescent, or horizontally oriented stripe or bar behind the eye; median keel of carapace topped with low black knobs on vertebral scutes 2-4 … 16
16a. Broad, squarish to rectangular blotch or bar behind the eye; spot under the eye and spot on lower jaw with a diameter greater than the iris (Fig. 19a) … Ouachita Map Turtle
16b. Narrow stripe or crescent behind the eye; if present, spot under the eye and spot on lower jaw with a diameter less than the iris (Fig. 19b) … False Map Turtle
