American red-bellied turtle
Pseudemys rubriventris is a large (to 40 cm) freshwater turtle having a reddish plastron and a prominent notch at the tip of the upper jaw, with a toothlike cusp on each side. Its elongated carapace is usually highest at the middle, widest behind the middle, flattened dorsally, and slightly serrated posteriorly. Vertebral 1 is as long as broad or longer than broad, the others are broader than long. The carapace is brown to black, with red or yellow markings on the pleurals and marginals. The 2nd pleural has a broad, light, central transverse band, which is forked at the upper or lower end or both. Each marginal has a red bar on the upper surface and a dark blotch with a light central spot on the lower surface. Melanism is common in old individuals. The plastron is reddish orange, and in the young has a dark mark that spreads along the seams but fades with age. A wide dark bar crosses the bridge. The plastral hindlobe is only slightly notched posteriorly, at best, and the plastral formula is: abd > an > pect > gul > fem >< hum. The head is moderate in size with a slightly protruding snout and a notched upper jaw (described above). Skin is dark olive with yellow stripes. A sagittal stripe passes anteriorly between the eyes and meets the joined supratemporal stripes on the snout, forming the prefrontal arrow that is characteristic of the red-bellied group. Five to eight stripes occur between the supratemporals behind the eyes. The paramedial stripes pass forward from the neck across the occipital region and terminate between the orbits. A supratemporal stripe bends upward from the neck on each side and enters the orbit.
Kiester and Childress (in Gorman, 1973) reported that the mitotic chromosomes total 50.
Males have long, straight foreclaws; large, thick tails, with the vent behind the carapacial margin; and lower, slightly narrower shells than females. Females are slightly larger than males.
Pseudemys rubriventris occurs along the Atlantic Coastal Plain from central New Jersey south to northeastern North Carolina and west up the Potomac River to eastern West Virginia. It also has relict populations in Plymouth County and possibly Essex County, Massachusetts.
No subspecies are currently recognized. In the past, the small colonies in Massachusetts were considered a separate race, Pseudemys rubriventris bangsi Babcock, 1937, based on a supposedly more domed carapace (greatest carapace length in redbellies from New England is 2.4 times its greatest height, that of turtles from more southern populations, 2.6). Conant (1951b) and Graham (1969) questioned this diagnostic character, and Ernst has observed that it is not valid in P. rubriventris from the Potomac River watershed. Recent statistical analyses of separate male and female data sets by Iverson and Graham (1990) revealed clinal variation in some male characters, but no obvious geographic variation in females. No geographic population showed enough morphological distinction to warrant subspecific status. An electrophoretic study using enzymes encoded for 12 presumed gene loci to determine polymorphism among four populations of P. rubriventris from Massachusetts (2), and New Jersey (2) did not reveal any significant differences in allele frequencies (Browne et al., 1996). No fixed allelic differences were found that unequivocally differentiated Massachusetts turtles from those from New Jersey. Turtles from all four populations shared common alleles, and unshared alleles were found only in one New Jersey population and an island population in Massachusetts. Estimated genetic distances among the four populations were low. The present disjunct range makes it unlikely that gene flow currently exists between the isolated Massachusetts populations of P. rubriventris and those from New Jersey, but the disjunction may be relatively recent.
Relatively large, deep bodies of water with basking sites are the preferred habitat. The red-bellied turtle has been found in creeks, river marshes, ponds, and lakes, and has also been taken from brackish water. The New England form is restricted to ponds.
Males first develop secondary sex characteristics at about 22 cm plastron length at nine years of age (Graham, 1971). Nothing is known about attainment of maturity by the female, or about the reproductive cycles of either sex. Courtship and mating of this shy turtle have not been described, but the elongated male foreclaws suggest some form of stroking is involved.
Nesting occurs from late May into July. The nest is flask shaped and about 10 cm deep. Several clutches are probably laid each season, and a single clutch may include from 10 to 17 elliptical (25-37 x 19-25 mm), parchmentlike-shelled eggs. Incubation takes 70-100 days, depending on weather conditions and latitude.
The hatchlings are 29-32 mm in carapace length. They are brightly colored and have rounded, keeled carapaces. The pink to red plastron has a large dark figure that spreads somewhat along the seams, a pattern similar to that of Pseudemys concinna.
The red-bellied turtle apparently is omnivorous. Known food items include snails, fish, tadpoles, crayfish, and aquatic vegetation. The fact that it is not often lured into traps baited with fish seems to indicate these are not a normal part of the diet. The median ridges on the crushing surfaces of the jaws are tuberculate, like those of P. concinna (probably an adaptation to a herbivorous diet); it is likely that P. rubriventris depends to a substantial degree on aquatic vegetation for nourishment.
IUCN Red List Status (1996)
Lower risk: near threatened. The population from New England is about 200 individuals restricted to a few ponds. It is considered endangered.