Werner, 1901
Siebenrock's snake-necked turtle
Recognition
This little-known Chelodina from New Guinea has been confused with C. rugosa of northern Australia and C. parkeri of New Guinea. It has an oblong dark-brown or black carapace (to 30 cm) which is broader behind the center and flattened dorsally. No vertebral keel is present, and females may have a slight medial depression. All vertebrals are broader than long; the 1st is flared anteriorly and is the largest, the 4th is the shortest, and the 5th is flared posteriorly. Normally no neural bones are present. The posterior marginals are neither flared nor serrated. The plastron is short, narrow, and elongated, leaving much of the carapacial opening uncovered. Its forelobe rounds to a point and the hindlobe is deeply notched posteriorly. The plastral formula is: intergul > pect > fem >< an > abd > hum > gul. The intergular scute is long and narrow (about twice as long as broad). The bridge is narrow. The plastron is yellow to light brown, and some individuals may have darkened seams. The broad head is large and flattened with a slightly protruding snout and an unnotched upper jaw. Numerous small irregularly shaped scales cover the dorsal surface. A variable number of chin barbels is present, often four or more. The neck is long and thick, reaching about 75% of the length of the carapace, and is covered with blunt tubercles. Head and neck are gray to brown dorsally, cream colored ventrally. The forelimbs contain enlarged transverse scales on their anterior surfaces, and the toes are webbed. The limbs and tail are gray.
Males have longer, thicker tails than do females, and are flatter shelled than are the more domed females.
Distribution
Chelodina siebenrocki occurs on the southern coast of New Guinea west of the Fly River, and on certain islands in the Torres Strait (Rhodin and Mittermeier, 1976).
Habitat
Chelodina siebenrocki inhabits the tidal areas of small streams, swamps, marshes, and offshore islands (Rhodin and Mittermeier, 1976).
Natural History
Mating takes place in water, with the male mounting the female from the rear. The female digs a nest at the end of the wet season in May and lays 4 to 19 elongated eggs (31.6-38.3 x 27.2-31.7 mm); the frequency of nesting in captivity suggests the potential of two clutches per season. Hatching occurs at the start of the next wet season in November or Decembers and may take three to six months in captivity. Hatchlings have carapace lengths of about 36 mm. Their carapaces are brown with small black spots; each marginal tends to have one spot but the number varies on the vertebrals and pleurals (Rhodin and Mittermeier, 1976; Rhodin and McCord, 1990).
Chelodina siebenrocki is apparently carnivorous, using its long neck to strike for food. Despite this, it is unaggressive and does not bite when handled.
It does not bask, but instead spends most of the time on or in deep mud.
IUCN Red List Status (1996)
Not listed.