Baur, 1893b
Alabama map turtle
Recognition
The Alabama map turtle is a moderate-sized (carapace length to 27.3 cm), relatively low-domed, medially keeled map turtle with a series of concentric yellow markings on the dorsal surface of each marginal scute. The keel is composed of laterally compressed knobs that are most prominent on the posterior portions of the second and third vertebrals. A black, often interrupted, medial stripe divides the dark-olive carapace, and narrow yellow vermiculations are present on each pleural scute. The hingeless, pale-yellow plastron is characterized by seam-following, and occasionally isolated, areas of dark pigment. Each marginal has a wide concentric set of dark rings on its ventral surface. The skin is brown to olive with light-yellow or yellowish green stripes and blotches. The head pattern resembles a mask, with a large interorbital blotch broadly fused to a pair of relatively narrow postorbital blotches. Neck stripes are relatively wide and vary little in width.
McKown (1972) reported that Graptemys pulchra (sensu lato) has 52 diploid chromosomes: 26 macrochromosomes with 48 arms and 26 microchromosomes with 26 arms. All other members of the genus Graptemys, except G. barbouri, have a total of 50 diploid chromosomes (McKown, 1972).
Adult females are over twice the size of mature males, and have conspicuously enlarged heads with broad crushing jaw surfaces. Males have longer tails with the vent posterior to the rim of the carapace. Both sexes have relatively flat plastra.
Distribution
The Alabama map turtle is restricted to the Mobile Bay drainage system in Alabama, Georgia (Harris et al., 1982; Santhuff and Wilson, 1990), and possibly Mississippi. Individuals have been collected in the Alabama, Cahaba, Tombigbee, Coosa, and Black Warrior Rivers, but it is apparently absent from the Tallapoosa River above the fall line in Alabama (Mount, 1975). Graptemys pulchra is expected in the Tombigbee River system of Mississippi as the sympatric G. nigrinoda has been collected there (Shoop, 1967).
Geographic variation
No subspecies are recognized.
Habitat
G. pulchra is an inhabitant of relatively large, swift creeks and rivers. Stream sections with abundant basking sites in the form of logs and brush are preferred. In rocky piedmont habitats males are usually found in shallow stretches (often in association with Sternotherus depressus and Apalone spinifera), but females seem to be restricted to deep pools or impoundments (Carl H. Ernst, pers. obs.).
Natural History
Males sometimes rapidly bob their heads at both sexes of Graptemys pulchra, and at other species of Graptemys. Perhaps this is courtship behavior. Nesting activity in G. pulchra (sensu lato) begins in late April or early May, reaches a peak in June, and continues through July and August. Six to seven clutches of four to six eggs are laid each year. Many nests are destroyed by predators. Hatchlings have been collected along the Cahaba River of Alabama in October (Jeffrey E. Lovich, pers. obs.).
The introduced Asian mussel Corbicula may be an important source of food for this species, particularly of the females (Marion, 1986; Carl H. Ernst, pers. obs.). In captivity, males eat fresh fish, newborn mice, snails, shrimp, trout chow, and occasionally romaine lettuce.
Remark
Map turtles tend to have small ranges restricted to a single drainage system. As originally described, G. pulchra had the most extensive range of any of these turtles. Lovich and McCoy (1992) demonstrated that G. pulchra (sensu lato) is composed of three distinct species, most confined to a single drainage system: G. pulchra — the Mobile Bay watershed, G. ernsti — the Escambia River drainage system, and G. gibbonsi —the Pearl and Pascagoula rivers.
IUCN Red List Status (1996)
Not listed.