Cann and Legler, 1994
Mary River turtle
Recognition
This is the probably largest (to 37.8 cm) short-necked chelid turtle in Australia. It has a low, smooth, elongated carapace with a slight medial depression on vertebrals 2-4, and flared marginals. The posteriormost marginals are smooth or only barely serrated. All vertebrals are at least slightly broader than long in adults. Vertebrals 3-4 are the longest, and the 5th is shortest and flared posteriorly. No neural bones are present. A cervical scute is always present. The unpatterned adult carapace is dull blackish brown. Plastron length is about 76% and bridge length 22% of that of the carapace. The anal scutes bear a distinct posterior notch. The intergular scute separates only the gulars. The plastral formula is pect > fem > an (or fem > pect = an) > abd > intergul > hum > gul. Plastron, bridge and undersides of the marginals are gray to dark gray and unpatterned. The head is narrow with only a slightly projecting snout, an unnotched upper jaw, and a distinct head shield. The triturating surface of the upper jaw is narrow and lacks a ridge. On the skull, the prefrontal and basal bones touch, preventing the maxilla from contacting the frontals. The prefrontals enter the dorsal rim of the orbit. The eyes are dull and dark with a vestigial nictitating membrane. Four chin barbels are present; the two medial ones are long and fleshy. Two dorsolateral rows of tubercles are present on the neck. All toes are webbed. The laterally compressed tail is distinctive in having a very large precloacal portion and a longitudinal, slit-like anal vent. Neck, limbs and tail are grayish dorsally, but lighter ventrally.
The male tail is massive ("almost the mass of a human wrist", Cann and Legler, 1994); that of the female is much shorter and smaller in diameter. Males also have a much deeper anal notch than do females. The female carapace is broader than that of the male.
Distribution
Elusor is known naturally only from the Mary River, Queensland, Australia, although it has appeared, probably as released pets, in some urban Australian reservoirs.
Geographic Variation
Apparently none.
Habitat
Waterways flowing through disturbed grazing areas with rocks protruding from banks and abundant sand banks for nesting.
Natural History
According to Cann and Legler (1994), nesting occurs in October and November on sand banks. Probably more than one clutch of 14-15 (possibly to 25), hard-shelled, 34.0-37.0 x 22.5-25.0 mm eggs is laid each year. Incubation takes about eight weeks. Hatchlings have 32-5-36.5 mm brown carapaces with smooth, unserrated marginals, and an instinct medial keel. The carapace scutes are imbricate in juveniles.
Elusor is omnivorous, feeding on algae and bivalve mollusks.
IUCN Red List Status (1996)
Endangered (B1+2c).