Description

The Black-knobbed Map Turtle, or Black-knobbed Sawback, is found extensively in central Alabama river systems, and can be found in the Cahaba River drainages in east Mississippi. Shells are nearly circular or slightly oval-shaped, with pronounced ridge of dark dorsal spines (hence “sawback”). The species is identified with its notable black knobs on the second and third vertebrals. G. nigrinoda can also be identified with the crescent shapes behind the eyes. They also exhibit microcephalic head dimensions (compared to their inhabiting conspecifics). Map turtles often bask on branches, logs, and other vegetative matter, often angled at 45°.

Identifying Traits

• Dark dorsal spines and notable keel
• Crescent marking behind eye

Habitat

Rivers, tributaries, and oxbow lakes related to their home river system

Behavior

Map turtles often bask on branches, logs, and other vegetative matter, often angled at 45°. 

Diet

Eats invertebrates and algae, diet still poorly known (Guyer et al., 2015)