A medium-sized species with a prominent keel along the center of the upper shell. The hind edge of the upper shell is strongly serrated. The upper shell is brown or olive with narrow, yellow, connected circles or lines. The lower shell is greenish yellow with several light brown lines following the scute seams. The head and neck are brown or greenish gray with numerous yellow lines bordered by dark brown or black. The thick yellow line behind each eye forms a backward L shape. A wide-eyed appearance is caused by the bright yellow eye with a round, black pupil.
Similar species: The Mississippi map turtle subspecies (G. p. kohnii) has a slightly different shape for the yellow mark behind each eye. Instead of having the L mark and narrow yellow lines touching the back of each eye, the Mississippi subspecies has a crescent behind each eye, and the yellow lines don’t touch the eye. In eastern Missouri, especially along the Mississippi, it can be difficult to tell the subspecies apart.