Testing area for the development of online keys to species.[edit]
Key to Australasian Chelidae
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 covered with distinct regular scales or low tubercles; 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
