The bog turtle (Glyptemys muhlenbergii) is a semiaquatic turtle endemic to the eastern United States. It was first scientifically described in 1801 after an 18th-century survey of Pennsylvania. It is the smallest North American turtle, measuring about 10 centimeters (4 in) long when fully grown. Although the bog turtle is similar in appearance to the painted or spotted turtles, its closest relative is actually the somewhat larger wood turtle.