(Gray, 1871)
Krefft's river turtle
Recognition
The oval, deeply domed adult carapace (to 28.1 cm) is broadest at the center, has a smooth posterior rim, but lacks a medial keel. A cervical scute is usually present, but neural bones are lacking. Vertebrals 1, 4, and 5 are broader than long, and the 5th is expanded posteriorly; vertebrals 2 and 3 may be as long as or longer than broad. Carapacial scutes are translucent and often rugose with raised longitudinal striations. The carapace ranges from olive brown to dark brown, with or without darker flecking. The plastron is long and narrow and the bridge is also narrow, leaving much of the carapacial opening uncovered. Its forelobe is rounded anteriorly and is broader than the hindlobe, which tapers to the rear and has an anal notch. The intergular is longer than broad and completely separates the gulars. The plastral formula is: pect > fem > abd > an > intergul > gul > hum. Both plastron and bridge are cream to yellow. The head is moderate with a slightly upturned, projecting snout and an unnotched upper jaw. The mandibular symphysis is broader than the greatest diameter of the orbit. Chin barbels are absent or only poorly developed. Smooth skin covers the dorsal surface of the head; the neck has numerous low rounded scales. Head, neck, and limbs are dark gray. A yellow to greenish gray stripe extends backward from the orbit to the tympanum, and a second stripe of the same color passes backward along the lower jaw to the neck. Both jaws and the chin are light gray.
Diploid chromosomes total 50 (Bull and Legler, 1980).
Females are larger and have higher domed shells and shorter tails than do the males.
Distribution
Emydura krefftii occurs in Queensland generally east of the Great Dividing Range from the Cape York Peninsula southward to Cape Charlotte Bay.
Geographic Variation
Two undescribedforms (subspecies or species cf. E. [l][m]Glossary[/m][r]krefftii[/r]krefftii) occur on Fraser Island and in the Cooper Creek drainage, Queensland; see Genus Emydura for more information.
Habitat
Emydura krefftii lives in rivers, streams, swamps, and lagoons. Legler and Cann (1980) commented that in rivers it occurs in riffles, but is most likely to be found associated with dead wood or undercut banks and never in the fastest water.
Natural History
Mating takes place in autumn, late winter and spring, and nesting probably from September to January (Georges, 1983). Cann (1978) reported his captives always chose a nesting site among ferns and shrubs.
The eggs are white, hard-shelled, and ellipsoidal (28.8-37.0 x 17.5-20.9 mm) (Georges, 1983); 82 eggs measured by Legler and Cann (1980) averaged 36.45 x 21.13 mm. Normal clutches may vary from 4 to about 18 eggs; Legler and Cann (1980) reported 82 eggs from five clutches, an average of 16 eggs per clutch. Hatchlings average 29.5 mm in carapace length (Georges, 1983), and have high-peaked, medially keeled carapaces with serrated posterior rims. Natural incubation may take 80 or more days.
Emydura krefftii is omnivorous, feeding on aquatic plants, fruits which drop into the water, aquatic bivalves and snails, small crustaceans, insects (both aquatic and terrestrial), and frogs. Small individuals are carnivorous, larger turtles more omnivorous.
Remark
Georges and Adams (1996) were unable to demonstrate electrophoretical differences between Emydura krefftii, E. signata, and E. macquarrii, and additionally pointed out the variability in morphological characters separating these species. In absence of concrete evidence to the contrary, they proposed these species should be synonymized.
IUCN Red List Status (1996)
Not listed.