Graptemys pseudogeographica (Gray, 1831)
Key Characters: Narrow vertical bar behind eye (sometimes forming semicircle); no large spot below eye or on lower jaw; low knob-bearing keel along midline of back.
Similar Species: Common Map Turtle, Ouachita Map Turtle. See Key to Adult Turtles of Illinois for help with identification.
Subspecies: Two subspecies are currently recognized, Mississippi Map Turtle, G. p. kohnii (Baur, 1890) and Northern False Map Turtle, G. p. pseudogeographica (Gray, 1831). Most of the Illinois specimens at hand are referable to G. p. pseudogeographica, but a few individuals from the Illinois River drainage have the kohnii head pattern. In addition to kohnii, pseudogeographica and ouachitensis, Smith (1960) listed a an additional subspecies in Illinois, G. p. versa Stejneger,1925 (Journ. Washington Acad. Sci. 15 (20): 462-463). However, this taxon (Texas Map Turtle), is now recognized as a full species and inhabits only the Colorado River drainage in central Texas.
Description: Medium-sized (up to 25 cm CL) turtle. Carapace brown to olive, with black or dark brown knobs. Posterior edge strongly toothed in young. Hatchling with orange or yellow rings on lateral carapace scutes and intricately whorled dark lines on plastron that fade to obscurity in adult. Head, neck, limbs, and tail liberally striped. Male with elongate foreclaws and cloacal opening behind end of carapace.
Habitat: Rivers and backwaters with mud bottoms and abundant basking sites.
Natural History: Extremely wary when basking, among first to dive into water when approached by boat. Omnivorous, feeding almost equally on plants and animals (mollusks and insects). Nests late May into early July. Female lays 2-3 clutches of ellipsoidal, flexible-shelled eggs (ca. 14/clutch).
Status: Locally common along Mississippi and Illinois rivers. Often confused with Ouachita map turtle in the literature. The Cook County populations may be introduced.
Etymology: Graptemys – grapho (Greek) meaning write; emydo (Greek) meaning ‘freshwater tortoise’; pseudogeographica – pseudos (Greek) meaning lie; geo (Greek) meaning earth; grapho (Greek) meaning write.
Original Description: Gray, J.E. 1831. Synopsis Reptilium or short descriptions of the species of reptiles. Part I. Cataphracta. Tortoises, crocodiles, and and enaliosaurians. Treuttel, Wurtz, and Co., London. Page 31.
Type Specimen: Syntypes, MNHN 9136-37 & 9146-47.
Type Locality: Not stated, designated “Wabash River, New Harmony, Indiana” by LeSeur (1827. Mem. Mus. Hist. Natur. Paris 15:257-268).
Original Name: Emys pseudogeographica Gray, 1831
Nomenclatural History: Listed as Malacoclemmys pseudo–geographica by Davis & Rice (1883. List of Batrachia and Reptilia of Illinois. Bulletin of the Chicago Academy of Sciences. vol. 1, no. 3) and Malaclemys pseudo–geographica by Hurter (1893. St. Louis Academy of Science Transactions 6(11):251-61) and Malaclemys lesueuri by Hurter (1911. Herpetology of Missouri. St. Louis Academy of Science Transactions 20(5):59-74).