(Baur, 1890a)
Ringed map turtle
Recognition
This narrow-headed map turtle (to 22 cm) has laterally compressed, black, spinelike vertebral projections and a slightly serrated posterior carapacial rim. Vertebrals are broader than long; the 1st is smallest. The carapace is dark olive green; each pleural has a broad yellow or orange circular mark, and each marginal is patterned with a wide yellow bar or semicircle. The plastron is yellow or orange, with an olive-brown pattern extending along the seams; this pattern fades with age. Its hindlobe is notched, and the plastral formula is: abd > fem >< an >< pect > gul > hum. The head is small to moderate in size with a nonprotruding snout and an upper jaw which is neither hooked nor notched. The head is black with yellow stripes, as is other skin. The variable postorbital marks are ovoid, rectangular, or rounded and usually not connected with the narrow dorsal longitudinal line. Two broad yellow stripes touch the orbit. The interorbital stripe is wide and is equal to or greater than the width of the broadest neck stripe. The lower jaw is marked with longitudinal yellow stripes as wide as the black interspaces. Ventrally, the neck bears three wide longitudinal stripes.
The diploid chromosome number is 50: 26 macrochromosomes and 24 microchromosomes (Killebrew, 1977a).
Adult males have long, thick tails, with the vent posterior to the carapace margin and close to the tail tip. Males also have elongated foreclaws. Adult females are 12-22 cm in carapace length, adult males 7.5-11.0 cm.
Distribution
Graptemys oculifera is restricted to the Pearl River system of Mississippi and Louisiana.
Habitat
Sand- and clay-bottomed rivers with rapid currents and abundant basking sites of brush, logs, and debris are preferred.
Natural History
Males become mature at about 6-7 cm in plastron length in years 4-5 (Kofron, 1991). The smallest mature female collected by Cagle (1953b) had a 12.8 cm plastron; similarly, Kofron (1991) reported mature females had plastron lengths of 12.7-18.9 cm. and were 7-8 years of age. Testes attain maximum size in August and September when spermatogenesis is apparently occurring.
Courtship has not been described, but the elongated male foreclaws indicate it is a "stroker". Females have oviducal eggs in May and June (Carl H. Ernst, pers. obs.), and eggs are deposited on sandbars in early June. Cagle (1953b) described an incomplete nest as a hole 3 cm in diameter and 3 cm deep leading to a cavity 9 cm in depth. A female collected by him on 4 June had three eggs in the left oviduct and none in the right; two of the oviducal eggs measured 40.3 x 20.6 and 40.0 x 21.0 mm. When found, she was depositing her first clutch of the season; enlarged ovocytes on her ovary indicated a second clutch of four eggs. Hatchlings emerge in late August or September and are 22-33 mm long.
Insects and mollusks are the primary foods. The scissorslike jaws are well-adapted for dismembering such animals.
This map turtle is fond of basking, but very shy, and slips into the water at the slightest disturbance.
IUCN Red List Status (1996)
Endangered (B1+2c) through pollution and collecting for the pet trade.