Graptemys is a genus of freshwater turtles containing 14 species, commonly known as map turtles.Crother, B. I. (editor) (2017). Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding. SSAR Herpetological Circular 43, 1–102 pp. [see page 86] Graptemys are small to medium-sized turtles that are significantly sexually dimorphic, with females in some species attaining as much as twice the length and ten times the mass as males. Depending on the species, adult males range from 7–16 cm (2.75–6.25 in), adult females 10–29.5 cm (4–11.62 in), and hatchlings 2.5–3.8 cm (1–1.5 in),Powell, Robert, Roger Conant, and Joseph T. Collins (2016). Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America. Boston and New York: Houghton Mifflin Harcourt. xiii + 494 pp. [pages 202-209] although some sources indicate female Barbour's map turtles (Graptemys barbouri) grow to 33 cm (13 in) in length.Sanderson, Roger A., and Jeffrey E. Lovich (1988). Graptemys barbouri. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles 421: 1-2. Most species have a distinctive dark pigmented keel that is often notched or serrated running down the center of the carapace and serrated scutes on the rear margin. The head, neck, and limbs exhibit bold patterns of yellow (occasionally orange or red) lines and spots against darker green, olive, or black base colors. The patterns on the head can be important characters in identifying the various species. The common name "map turtle" is derived from the intricate patterns on their shells that are suggestive of topographical maps, although the patterns are more apparent in some species than others, and often become obscure in older specimens. Some species are occasionally called "sawbacks", in reference to the serrated keels on their shell.Lindeman, Peter V. (2013). The Map Turtle and Sawback Atlas, Ecology, Evolution, Distribution, and Conservation. (Vol. 12 Animal Natural History Series). Norman, Oklahoma: University of Oklahoma Press. xxi + 460 pp. Ernst, C. H., and J. E. Lovich (2009). Turtles of the United States and Canada. Baltimore, Maryland: Johns Hopkins University Press. xii + 827 pp.
They are endemic to North America, where most species occur in the rivers of the Gulf Coast of the United States, although three species are more wide-ranging, dispersed throughout the eastern two thirds of the greater Mississippi River basin, into the Great Lakes region, and east to New York and southeast Canada. Most Graptemys are lotic (river) turtles, having a preference for moving water and larger lakes, and with long legs, broad feet, and long fully webbed digits they are well adapted for swimming in currents. They primarily feed on fresh water mussels, clams, snails, insects (including larva and eggs), bryozoans, sponges, algae, and various vegetation. Fish only appear in the diets of a few species and then only in a relatively small percentage of the diet. Within this spectrum of food items there is significant niche partitioning among the sexually dimorphic males and females, and microcephalic, mesocephalic, and megacephalic species occurring in the same river drainages. Like all turtles, map turtles are oviparous, typically laying eggs from late June to August. Females lay two to fifteen eggs per clutch and, depending on a number of variables such as species, size, and age, among other factors, may skip a year between clutches, or lay as many four clutches a year.
Seven of the 14 species are listed as either near threatened, vulnerable, or endangered by the IUCN Red List as of 2021,IUCN Red List: Search, Graptemys (accessed 29 October 2021) and two species, the yellow-blotched map turtle (G. flavimaculata) and the ringed map turtle (G. oculifera) are listed as threatened by the U.S. Federal Government.U.S. Fish & Wildlife Service, Species by Taxonomic Group - Reptiles (accessed 29 October 2021)
Species
The following species and subspecies are recognized as being valid (listed alphabetically by specific name and subspecific name). Nota bene: A binomial authority or trinomial authority in parentheses indicates that the species or subspecies was originally described in a genus other than Graptemys.
Extant species Graptemys barbouri Carr & Marchand, 1942 – Barbour's map turtle Graptemys caglei Haynes & McKown, 1974 – Cagle's map turtle Graptemys ernsti Lovich & McCoy, 1992 – Escambia map turtle Graptemys flavimaculata Cagle, 1954 – yellow-blotched map turtle or yellow-blotched sawback Graptemys geographica (Lesueur, 1817) – northern map turtle, formerly known as the common map turtle Graptemys gibbonsi Lovich & McCoy, 1992 – Pascagoula map turtle Graptemys nigrinoda Cagle, 1954 – black-knobbed map turtle Graptemys oculifera (Baur, 1890) – ringed map turtle Graptemys ouachitensis Cagle, 1953 – Ouachita map turtle Graptemys pearlensis Ennen, Lovich, Kreiser, Selman, Qualls, 2010 – Pearl River map turtleEnnen, Joshua R., Jeffrey E. Lovich, Brian R. Kreiser, Will Selman, and Carl P. Qualls (2010). '"Genetic and Morphological Variation Between Populations of the Pascagoula Map Turtle (Graptemys gibbonsi) in the Pearl and Pascagoula Rivers with Description of a New Species". Chelonian Conservation and Biology 9 (1): 98–113. Graptemys pseudogeographica (Gray, 1831) – false map turtle G. p. kohnii (Baur, 1890) – Mississippi map turtle G. p. pseudogeographica (Gray, 1831) – false map turtle Graptemys pulchra Baur, 1893 – Alabama map turtle Graptemys sabinensis Cagle, 1953 – Sabine map turtle Graptemys versa Stejneger, 1925 – Texas map turtle
Fossil species An extinct species from the Suwannee River drainage in Florida, Graptemys kerneri belonging to the female megacephalic subclade, was described in 2011 from Pleistocene fossil records. Graptemys kerneri Ehret & Bourque, 2011
Etymology
The generic name Graptemys is derived from two compounded Greek words, graptos, meaning inscribed or in writing, in reference to the patterns on the turtles shells, and emydos, meaning a freshwater turtle. The trivial names, or specific epithets, of four of the species in the genus are patronyms or eponyms, named in honor of prominent herpetologist, each of whom made significant contributions to studies on North American turtles: Thomas Barbour (G. barbouri); Fred Ray Cagle (G. caglei); Carl Henry Ernst (G. ernsti); J. Whitfield Gibbons (G. gibbonsi). One subspecies is named for the collector of the type specimen, Joseph Gustave Kohn (G. pseudogeographica kohnii).Beolens, Bo, Michael Watkins, and Michael Grayson (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. Three species are named for the rivers in which they were first discovered: Ouachita River (G. ouachitensis); Sabine River (G. sabinensis); Pearl River (G. pearlensis).Cagle, Fred R. (1953). "Two new subspecies of Graptemys pseudogeographica." Occasional Papers of the Museum of Zoology, University of Michigan 564: 1-17. The other species are all named for various aspects of the topographic map like patterns and other markings, colors, and contours of the carapace, that are most apparent in the juveniles and young adults of these attractive turtles: G. flavimaculata, flavus = yellow, maculatus = spotted or blotched;McCoy, C. J., and Richard C. Vogt (1987). Graptemys flavimaculata. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles. 403: 1-2. G. geographica, geographica = geographic map like;McCoy, C. J., and Richard C. Vogt (1990). Graptemys geographica. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles. 484: 1-4. G. nigrinoda, niger = black, nodus = knot, node, or knob;Lahanas, P. N. (1986). Graptemys nigrinoda. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles. 396: 1-2. G. oculifera, oculus = eye, fero = to bear (eye shape rings on the pleurals scutes);McCoy, C. J., and Richard C. Vogt (1988). Graptemys oculifera. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles. 422: 1-2. G. pseudogeographica, pseudo = false, geographica = geographic map like;Vogt, Richard C (1995). Graptemys pseudogeographica. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles. 604: 1-6. G. pulchra, pulchra = beautiful;Lovich, J. E. (1985). Graptemys pulchra. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles. 360: 1-2. G. versa, vers = to change (probably referring to the contrasting head patterns compared to G. pseudogeographica).Vogt, Richard C. (1981). Graptemys versa. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles. 280: 1-2.
Description
Graptemys species superficially resemble many other species of aquatic turtles, including sliders (Trachemys) and cooters (Pseudemys). However, they are distinguished by a keel that runs the length of the center of the carapace. In some southern species, the keel can result in vertebral spines, resulting in the map turtle's other common name — "sawback". They also typically grow to a smaller size at maturity. They are given the common name "map turtle" due to the map-like markings on the carapace. Map turtles are known for intricate head markings and strong sexual dimorphism with mature females twice the length and 10 times the mass of mature males.
Feeding morphology Females of all map turtle species can be partitioned into three groups based on head (alveolar) width and corresponding ecology and phylogeny. Microcephalic females are narrow headed, sympatric with a broader headed species, and consume few mollusks. Microcephalic species include yellow-blotched, black-knobbed, ringed, Ouachita, and Sabine map turtles. Mesocephalic females have moderately broad heads and tend to eat mostly mollusks along with softer bodied prey. Mesocephalic species include Cagle's, northern, false, Mississippi, and Texas map turtles. Megacephalic females have exceptionally broad heads, and feed almost exclusively on mollusks. Megacephalic females include Barbour's, Escambia, Pascagoula, Pearl River, and Alabama map turtles. Males do not fit neatly into the three groups describing head width, with differences in head width likely not influencing diet. Due to these differences in head size and jaw strength, females tend to eat much larger prey than the males such as snails, clams, and crayfish whereas the males eat insects and smaller crustaceans. Including deadwood material inside of the Graptemys habitat then the chances of more Graptemys migrating or being born in that area is greater. The population can use a healthy habitat that can support a significant number of Graptemys and dead wood will help with this.
Distribution