Graptemys pseudogeographica

G. ouachitensis formerly was regarded as a subspecies of G. pseudogeographica. Ernst and Barbour (1989) and Conant and Collins (1991) treated Graptemys kohni as a species but noted the need for further study of the relationships among G. kohni, G. ouachitensis, G. pseudogeographica. Vogt (1993) reviewed the systematics of the G. pseudogeographica complex and determined that G. ouachitensis is a distinct species and that kohni is best regarded as a subspecies of G. pseudogeographica. MtDNA data support the recognition of G. ouachitensis and G. pseudogeographica as distinct species and show that kohni clearly falls within the pseudogeographica clade (Lamb et al. 1994).

Lamb et al. (1994) conducted a mtDNA-based phylogenetic analysis of turtles in the genus Graptemys and discovered three monophyletic lineages: G. pulchra group (including G. pulchra, G. gibbonsi, G. ernsti, and G. barbouri); G. pseudogeographica group (including G. pseudogeographica, G. nigrinoda, G. flavimaculata, G. oculifera, G. versa, G. caglei, and G. ouachitensis); and G. geographica. Overall genetic divergence was relatively low, and G. pseudogeographica, G. nigrinoda, G. flavimaculata, G. oculifera, and G. versa all shared the same mtDNA genotype. There was no evidence of infraspecific variation in any species. Walker and Avise (1998) reviewed these data and suggested that the Graptemys complex has been taxonomically oversplit at the species level.

McDowell (1964) concluded that the genus Graptemys should be included in the genus Malaclemys, but this arrangement generally has been rejected (e.g., see Dobie 1981 for information on osteological differences between the two genera).

See Freedberg and Myers (2012) and Mitchell et al. (2016) confirming hybridization between G. geographica and G. pseudogeographica.

Widespread and possibly abundant in large rivers of the Mississippi River Basin; possible localized declines, but population trends are not well known; may be moderately threatened due to loss of habitat and collecting; in general, current status is not well documented.

Occurs primarily in large rivers of the Mississippi River Basin, from the St. Croix and Wisconsin rivers in northern and central Wisconsin and the upper Mississippi River in Minnesota south through Louisiana and eastern Texas; range follows the Missouri River into North Dakota and extends east to western Tennessee, western Kentucky, Indiana, and central Ohio (Vogt 1993). See Vogt (1993, 1995) for spot maps and a list of localities for turtles of confirmed identity. Introduced and established in southeastern Virginia (subspecies kohnii) (Savitzky and Mitchell 2001).

Extant in 100s of locations in many rivers.

The greatest threats to survival are destruction of nesting habitat and nests by camping tourists, agricultural practices, and pollution. In Missouri and South Dakota, numbers are decreasing, possibly due to several factors including water pollution, river channelization, impoundments, reduction of suitable nesting sites, siltation, and unlawful shooting (Ernst et al. 1994; CITES Proposal 1996; Doug Backlund, pers. comm., 1998). Individuals are also limited by the availability of basking sites in the form of deadwood. Therefore, the removal of deadwood by humans is detrimental (Lindeman, in press). Human-caused mortalities include drowning in gill nets, shooting, and setlines for fish. In the South, these trutles are collected and eaten, primarily in Louisiana. In the past, they were collected for the pet trade. Additional threats include individuals freezing when water levels drop during winter months, and hatchlings being devoured in large numbers by the maggots of the fly METOPOSARCOPHAGA IMPORTANS. In Wisconsin, 36% of hatchlings found in 23 clutches were devoured by maggots (Ernst et al. 1994, CITES Proposal 1996). Considered not very threatened by the Ohio Natural Heritage Program, where over the past 10 years water quality and presumably habitat have improved in the lower Scioto River, Ohio (Dan Rice, pers. comm., 1998). The Missouri and Kentucky natural heritage programs consider it to be not very threatened, while South Dakota states that it is moderately threatened (Janet Sternburg, Doug Backlund, and Brainard Palmer-Ball, pers. comm., 1998).