MISSISSIPPI MAP TURTLE (Graptemys kohnii), (BAUR, 1890)
IDENTIFICATION: A medium sized turtle with an adult maximum shell length of 13.2 cm (5.1") for males (specimen from Fort Worth, Texas) and 27.7 cm (10.9") for females. The carapace is olive to greenish brown with a dark midline keel that reaches its highest point on the second vertebral scute. The marking of the keel can vary from a continuous dark stripe to a broken one. Light yellow to orange concentric lines are present on the carapace. The posterior marginal scutes are serrated. The plastron and bridge is creamy yellow and can vary with some having dark markings along the seams and others also having dark patches on the plastron. This variation can be found among specimens within the same population. The head is dark green with several yellowish-white to reddish orange stripes bordered with black. One stripe forms a crescent behind and below the eye preventing any other stripes from reaching the eye. The thickness and coloration of this crescent varies among populations. In some localities the crescent may be broad and thin in others. A medial stripe extends from the snout towards the back of the head. The chin has a medial spot and several thin stripes. Asides from being substantially larger than males, mature females develop very large heads which accommodate muscles necessary to crack and feed upon fresh water mussels. Asides from the males being diminutive in size compared to females their heads are much smaller and allow them to seek out their preferred prey of aquatic invertebrates.
The original description of Graptemys kohnii (then described as Malaclemmys kohnii) as presented in: Baur, G. 1890. Two New Species of Tortoises from the South. Science, (Ser. 1) 16: 263