Order Testudines
Suborder Pleurodira

Family Chelidae

Appearance:

photo: http://itgmv1.fzk.de/www/itg/uetz/herp/photos/Chelus_fimbriatus.jpg

Morphology: Chelids are characterized by unusually extensive emargination of the cheekbones so that only a parietal-squamosal bar remains. Quadratojugals and mesoplastra are absent, distinguishing chelids from pelomedusids. Key osteological features: cervical scute present; neurals reduced, 7 or fewer, absent in some; 9 plastral bones, mesoplastra absent; no quadratojugal or temporal arch; prefrontals not in contact; palatals separated by vomer; lower jaw usually slender and weak; neck incompletely retractile; 5th & 6th cervicals amphicoelous, none saddle-shaped; neck typically very long, retracted by 1 or 2 lateral bends; cervical scute usually present, absent in 1 genus;

Size: 15 centimeters in carapace length (Pseudemydura umbrina) to nearly 50 centimeters (Chelodina expansa) .

Distribution: South America, Australia, and New Guinea.

Habitat: Aquatic or semi-aquatic. Most species inhabit slow-moving freshwater or swamps, although Chelodina siebenrocki also occurs in brackish water.

Food: Fish and aquatic invertebrates.

Reproduction: Some populations of Platemys platycephala exhibit an unusual form of triploidy in which individual cells are diploid or triploid within an individual (Bickhamn et al. 1985).

Behavior:

Relationships:

List of subfamilies and genera (modified after Georges et al. 1998):

Subfamily Chelodininae Chelodina Elseya Elusor Emydura Macrochelodina Macrodiremys Pseudemydura Rheodytes Subfamily Chelidinae Acanthochelys Chelus Mesoclemmys (incl. Batrachemys and Ranacephala) Phrynops Platemys Rhinemys Subfamily Hydromedusinae Hydromedusa

For definitions of the genera Mesoclemmys, Phrynops, Batrachemys, Rhinemys, Ranacephala, and Bufocephala, see McCord et al. (2001).

Click on genus to get a list of species. Use the Search form for more sophisticated searches (HELP on Search).

Phylogeny of pleurodiran turtles (after Georges et al. 1998):

A consensus of nodes in the pleurodiran phylogeny to receive 70% or greater bootstrap support in one or more of the maximum parsimony (weighted and unweighted) or maximum likelihood sub-analyses. Numbers shown in parentheses give the analyses that provide the support: 1, restricted taxon set using 12S rRNA, 16S rRNA and c-mos; 2, all taxa using 12S rRNA and 16S rRNA only; 3, Australasian chelids using 12S rRNA, 16S rRNA and CO1. Numbers bearing an asterisk indicate that bootstrap support was equal to or greater than 70% only in some of the three sub-analyses.

References:

Ernst,C.H. & Barbour,R.W. (1989)
Turtles of the World
Smithsonian Institution Press, Washington D.C. - London
ISBN 0-87474-414-8

Fujita, M.K.; Tag N. Engstrom, David E. Starkey and H. Bradley Shaffer (2004)
Turtle phylogeny: insights from a novel nuclear intron.
Molecular Phylogenetics and Evolution 31 (3): 1031-1040

Gaffney, Eugene S. (1977)
The side-necked turtle family Chelidae: a theory of relationships using shared derived characters.
American Museum Novitates (2620): 1-28

Georges, A. (1996)
Electrophoretic delineation of species boundaries within the short-necked freshwater turtles of Australia (Testudines: Chelidae)
Zoological Journal of the Linnean Society (1996), 118: 241&endash;260.

Georges, A.; J. Birrell, K. M. Saint, W. McCord und S. C. Donnellan (1998)
A phylogeny for side-necked turtles (Chelonia: Pleurodira) based on mitochondrial and nuclear gene sequence variation
Biological Journal of the Linnean Society 67: 213-246 [1999]

Georges, A.; Adams, M.; McCord, W. 2002
Electrophoretic delineation of species boundaries within the genus Chelodina (Testudines: Chelidae) of Australia, New Guinea and Indonesia.
Zoological Journal of the Linnean Society 134 (4): 401-422

Lieb, Carl S.; Jack W. Sites, Jr. & James W. Archie (1999)
The use of isozyme characters in systematic studies of turtles: preliminary data for Australian Chelids.
Biochemical Systematics and Ecology 27: 157-183

McCord, W. P., J.-O. Mehdi & W. W. Lamar 2001
A taxonomic reevaluation of Phrynops (Testudines: Chelidae) with the description of two new genera and a new species of Batrachemys.
Rev. Biol. Trop., 49 (2): 715-764

McCord, W. P. & S. A. Thomson 2002
A new species of Chelodina (Testudines: Pleurodira: Chelidae) from Northern Australia.
J. Herpetol. 36 (2): 255-267.

Pough, F. Harvey; Andrews, Robin M.; Cadle, John E.; Crump, Martha L.; Savitzky, Alan H. & Kentwood D. Wells (1998)
Herpetology.
Upper Saddle River, NJ [USA] (Prentice-Hall, Inc.), xi + 577 pp.

Seddon, J. M.;Georges, A.;Baverstock, P. R.;McCord, W. 1997
Phylogenetic relationships of chelid turtles (Pleurodira: Chelidae) based on mitochondrial 12S rRNA gene sequence variation.
Mol Phylogenet Evol 7 (1): 55-61

Wermuth,H. & Mertens,R. (1977)
Liste der rezenten Amphibien und Reptilien:
Testudines, Crocodylia, Rhynchocephalia
Das Tierreich, Lfg. 100, XXVII + 174 pp.
Walter de Gruyter, Berlin-New York

Online References:

World Chelonian Trust

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