Ouachita map turtle

LC - Least Concern

N5 - Secure

S4 - Apparently Secure

not listed

Ouachita map turtle is one of three map turtles that occur in Minnesota. It occurs in the United States from Ohio to Alabama, west to Minnesota and eastern Texas. It is found in large rivers and in pools and lakes fed by those rivers. In Minnesota it is found in and near the Mississippi River from Houston County north to Anoka County.

Size is usually given as the length of the upper shell (carapace). The male carapace is 3½″ to 7″ (9.0 to 17.8 cm) long. Females are much larger, with a carapace 4¾″ to 10¼″ (12 to 26 cm) long.

The carapace is dark olive to dark brown. It is marked with a network of fine, faintly visible, yellow lines on the side (pleural) and marginal scales (scutes). The lines resemble contour lines on a map. This is the feature that gives the genus its common name. The lines are distinct on juveniles but become less distinct as the turtle matures. On older individuals, they may not be visible unless the carapace is wet. There is a black, smudge-like spot on the rear margin of the third, fourth, and fifth pleural scutes, and a similar small spot at the outer rear corner of the seventh through twelfth marginal scutes. The rear margin is flared and saw-toothed. On young turtles the carapace is distinctly keeled, and there is a longitudinal row of saw-toothed knobs down the middle. On mature adults it is only slightly keeled. The knobs on the second and third central (vertebral) scutes are retained at maturity on both sexes. On males the knobs remain pronounced, but on mature females they may be flattened and broadened or indistinct.

The lower shell (plastron) is cream-colored or yellow. On juveniles there is a pattern of two or four longitudinal black lines interrupted at the edges of each scute. On adults these lines are sometimes retained but are usually absent or barely visible on larger individuals.

The head, neck, and limbs are olive to dark olive with thin yellow or yellowish-white lines on the legs, tail, chin, and neck. The eyes are housed in bony orbits. Only one to three lines extend to the orbit. There are three yellow spots on each side of the head: one behind each eye (postorbital), one below the eye (suborbital), and one on the side of the lower jaw. The postorbital spot is square or rectangular.

Male carapace length: 3½″ to 7″ (9.0 to 17.8 cm)

Female carapace length: 4¾″ to 10¼″ (12 to 26 cm)

Large rivers and pools and lakes fed by those rivers

15 to 20 years (in captivity)

Mostly vegetation, including pondweed, duckweed, manna grass, and algae, and insects, including larvae of mayflies, caddisflies, beetles, and flies.

Sources

4, 14, 24, 29, 30, 76, 78.

This species was formerly classified as a subspecies of false map turtle (Graptemys pseudogeographica). A recent analysis of the genus Graptemys (Praschag, et al., 2017) contends that the genus has been overly split. It suggests that Graptemys ouachitensis should be returned to subspecies status, but it does not explicitly make the move.

In 1953 Cagle described two new subspecies of Graptemys pseudogeographica based on several morphological features. In 2017 Sabine map turtle (Grapternys pseudogeogmphica sabinensis) was raised to full species status.

Location: Wagon Wheel Trail in La Crescent, MN.

Location: Wabasha County