Graptemys pseudogeographica

(Gray, 1831b)
False map turtle

The false map turtle is a fairly large freshwater species (male carapace length to 15 cm, females to 27 cm) with a concave anterior profile, a distinct medial keel bearing conspicuous low spines, and a strongly serrated posterior rim. Its carapace is olive to brown with yellow oval markings and dark blotches on each pleural. Both the upper and lower marginal surfaces have a yellow ocellus at each seam. The bridge is marked with light bars, and the plastron is immaculate cream to yellow in adults, but small individuals have a pattern of dark lines bordering the seams. The head is narrow to moderately broad with a nonprotruding snout and no medial notch or hook on the upper jaw. Skin is olive to brown, with many narrow yellow stripes on the legs, tail, chin, and neck. The small postorbital mark is variable but commonly consists of a narrow downward extension of a neck stripe behind the orbit which allows four to seven neck stripes to contact the orbit (or prevents any from reaching the orbit; see section on geographic variation).
The diploid chromosome number is 50: 20 metacentric and submetacentric, 10 subtelocentric, and 20 acrocentric and telocentric chromosomes with a total of 80 arms (Stock, 1972; Killebrew, 1977a).
Adult males have long, thick tails, with the vent posterior to the carapacial rim, and elongated foreclaws (especially the third). Adult females are, on average, 1.50-1.74 times larger than adult males and have wider heads (Gibbons and Lovich, 1990).

Graptemys pseudogeographica occurs primarily in large streams of the Missouri and Mississippi river systems from Ohio, Indiana, Illinois, Wisconsin, Minnesota, and the Dakotas southward possibly to extreme southwestern Alabama, southern and western Mississippi, Louisiana, and eastern Texas.

Geographic Variation
Two subspecies are currently recognized (Vogt, 1993). Graptemys pseudogeographica pseudogeographica (Gray, 1831b), the false map turtle, is described above. It occurs from Ohio, Indiana, Illinois, Wisconsin, Minnesota, and the Dakotas southward to western Kentucky, Tennessee, and Missouri. Graptemys p. kohnii (Baur, 1890a), the Mississippi map turtle, differs from the nominate race in having the curved stripe behind the eye so long that it usually prevents any neck stripe from reaching the orbit, a white iris (brownish or bronze in the nominate subspecies), and a more extensive plastron pattern. It is found in the Mississippi River watershed from western Tennessee, central Missouri, and possibly southeastern Nebraska south to eastern Texas, Louisiana, and southern and western Mississippi. There is also a questionable record from the vicinity of Mobile, Alabama (Mount, 1975). Most of its range lies west of the Mississippi River. Jones et al. (1991) thought the G. p. kohnii recently found in the Pearl River, Mississippi, came from the pet trade, but McCoy and Vogt (1992) suggested these turtles may have been introduced into the Pearl watershed during the April 1979 flood of the Mississippi River.

The false map turtle lives primarily in large rivers and their backwaters, but also occupies lakes, ponds, sloughs, bayous, oxbows, and occasionally marshes. It prefers water with abundant aquatic vegetation, places to bask, and slow currents, but can be found in swiftly flowing main channels of large rivers. It seems to avoid a sand substrate, but prefer mud bottoms (Fuselier and Edds, 1994).

Natural History
Males begin to mature at 7.5-10.0 cm plastron length in 4-6 years, and females at mature at 18-19 cm plastron length in about 8 years (Timken, 1968; Vogt, 1980). The female ovarian cycle begins between late June and mid-July after she has deposited her last clutch of eggs for the year, and she enters hibernation with their coelomic cavity encroached on by enlarged follicles (Vogt, 1980). The male testis is largest in the fall and smallest in summer (Vogt, 1980).
Courtship and mating occur in the April and May. During courtship the male strokes the females face with his elongated foreclaws (Ernst, 1974b). Females oviposit from late May to July in flask shaped nest on beaches adjacent to their waterways. Just prior to nesting, large numbers of females gather in the water off the nesting beaches. Most nesting is done in the morning from 06:30 to 10:00, but some females nest in the late afternoon and evening.
Two and possibly three clutches of 8-22 eggs are laid per season. The white eggs are elliptical (32.3-41.0 x 17.9-26.2 mm). Natural incubation takes 52-85 days; hatching occurs in late summer or early fall. The hatchlings are brightly colored with a prominent keel, and 25.0-37.0 mm carapace.
Graptemys pseudogeographica is a generalist omnivore, feeding on mollusks (both bivalves and snails), crayfish, insects, fish carrion, and plant material including Cabomba, Ceratophyllum, Lemna, Potamogeton, and Vallisneria. In captivity it readily consumes fish, snails, clams, earthworms, crickets, and romaine lettuce.

Cagle (1953a) originally described G. ouachitensis ouachitensis and G. o. sabinensis as subspecies of G. pseudogeographica. Studies by Vogt (1993) have shown that G. ouachitensis and G. pseudogeographica are separate species. Separation of G. ouachitensis, G. p. kohnii, and G. p. pseudogeographica is mostly on the basis of head pattern, but Ewert (1979) and Vogt (1980, 1993) noted that various head patterns may be produced by different incubation temperatures, and that a single clutch may produce several head patterns.

Bour and Dubois (1983b) examined the type specimens of Emys pseudogeographica Gray, 1831b and E. lesueuri Gray, 1831b, and determined that the latter is a junior synonym of the former.

IUCN Red List Status (1996)
Not listed.