Family CHELIDAE

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Introduction

A family of aquatic and semi-aquatic turtles, containing about 55 species in 15 genera, of which 7 genera and 32 species are endemic to Australia, New Guinea, Timor and Roti. The remaining members of the family are restricted to South America, and fossil forms are not known outside their current range. As such, they are of undisputed Gondwanan origin. Pleurodirous (head and neck withdraw sideways into shell); carapace and plastron rigid (plastron mildly kinetic in Pseudemydura umbrina, overlaid by distinct epidermal scutes; mesoplastral bones absent; forelimbs and hindlimbs with distinct ankle-joints (not paddle-shaped) and four or five claws on distinct webbed feet. [Description from Georges & Thomson 2010]

Diagnosis

Characterised in Australia by: limbs jointed, not paddle-shaped, with 4- or 5-clawed, webbed feet; barbels well developed in most species; pleurodirous.

ID Keys

Key to Chelid Genera from Georges & Thomson 2010

1 - Forelimbs each with five claws; gular scutes separated by the intergular; intergular scute in broad contact with the anterior margin of the plastron -.................................................................................................................................................................................................................................................2
- Forelimbs each with four claws; gular scutes in contact; intergular scute not in broad contact with the anterior margin of the plastron -..................................................................................................................................................................................................................................Chelodina
2 - Intergular scute not in contact with the pectoral scutes -
.................................................................................................................................................................................................................................................3
- Intergular scute contacts and partly separates the pectoral scutes -
..........................................................................................................................................................................................................................Pseudemydura
3 - Suture between the second and third costal scutes contacting the seventh marginal scute; suture between the third and fourth costal scutes contacting the ninth marginal scute -
.................................................................................................................................................................................................................................................4
- Suture between the second and third costal scutes contacting the sixth marginal scute; suture between the third and fourth costal scutes contacting the eighth marginal scute -.................................................................................................................................................................................................................................Rheodytes

4 - Surface of the temporal region smooth, sometimes broken into regular scales of low relief; dorsal surface of the head with a prominent head shield which may be entire or fragmented; cervical scute present or absent -.................................................................................................................................................................................................................................................5
- Skin of the temporal region smooth, sometimes broken into regular scales of low relief; dorsal surface of head without a prominent head shield; cervical scute present (except as a rare variant) - ....................................................................................................................................................................................................................................Emydura

5 - Precloacal tail length greater than postcloacal length only in adult males; tail round in cross section; cloacal orifice round; tail always shorter than half of carapace length -.................................................................................................................................................................................................................................................6
- Tail distinctive and large; precloacal length greater than postcloacal length at all ages in both sexes; tail laterally compressed; cloacal orifice a longitudinal slit; tail up to 53% of carapace length in adult males -........................................................................................................................................................................................................................................Elusor

6 - Prominent alveolar ridge on the triturating surfaces of the mouth; cervical scute absent (except as a rare variant); no prominent process of the head shield extending down the parietal ridge toward the tympanum - ........................................................................................................................................................................................................................................Elseya
- Alveolar ridge absent; cervical scute absent in Australian species (except as a rare variant), present in New Guinea species (except as a rare variant); posterior process of the head shield extends laterally down the parietal ridge toward the tympanum - .................................................................................................................................................................................................................................Myuchelys

Diagnosis References

Georges, A. & Thomson, S. 2010. Diversity of Australasian freshwater turtles, with an annotated synonymy and keys to species. Zootaxa 2496: 1-37 [12-13]

General References

Cann, J. 1978. Tortoises of Australia. Sydney : Angus & Robertson 79 pp.

Cogger, H.G. 1979. Reptiles and Amphibians of Australia. Sydney : A.H. & A.W. Reed 608 pp.

Fritz, U. & Havas, P. 2007. Checklist of Chelonians of the World. Vertebrate Zoology 57(2): 149-368 (checklist of world chelonians)

Georges, A. & Thomson, S. 2010. Diversity of Australasian freshwater turtles, with an annotated synonymy and keys to species. Zootaxa 2496: 1-37 [12-13]

Goode, J. 1967. Freshwater Tortoises of Australia and New Guinea. Melbourne : Landsdowne Press x 154 pp.

Le, M., Reid, B.N., McCord, W.P., Naro-Maciel, E., Raxworthy, C.J., Amato, G. & Georges, A. 2013. Resolving the phylogenetic history of the short-necked turtles, genera Elseya and Myuchelys (Testudines: Chelidae) from Australia and New Guinea. Molecular Phylogenetics and Evolution 68: 251–258 (use the name Myuchelys, not Wollumbinia)

Wermuth, H. & Mertens, R. 1961. Schildkröten, Krokodile, Brückenechsen. Jena : Gustav Fischer 422 pp.

Wermuth, H. & Mertens, R. 1977. Liste der rezenten Amphibien und Reptilien; Testudines, Crocodylia, Rhynchocephalia. Das Tierreich 100: i-xxvii, 1-174

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