Black-knobbed Map Turtle vs. Alabama Map Turtle

In Mississippi both map turtles live in the Tombigbee. A: Rounded, flattened, jet-black knobs in the Black-knobbed Map Turtle; knobs low, with a black stripe running along them in the Alabama Map Turtle. B: A boomerang-shaped mark behind each eye, joined over the head; only a narrow line or none between the eyes in the Black-knobbed Map Turtle; a big blotch between the eyes joined to the blotch behind each eye; old females' heads huge in the Alabama Map Turtle. Each side plate of the Black-knobbed carries a circle or half-circle drawn in a narrow yellow line; the Alabama Map Turtle's shell has a fine net of yellow lines. Female Black-knobbed stay under 8.5 in; female Alabama Map Turtles reach 11.5 in.

Photographs via iNaturalist under Creative Commons licences; the photographers are credited on the sheet.

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