Chinemys nigricans

(Gray, 1834a)
Chinese red-necked pond turtle

The carapace is elongated (to 20.5 cm), slightly domed, unserrated posteriorly, and has only a single, pronounced medial keel. Vertebrals 1, 4, and 5 are broader than long; 2 and 3 may be or are as broad as long. The 1st and 4th vertebrals are usually broadest. Lateral marginals may be upturned. The carapace is brown to chestnut brown in adult males and dark green to dark gray or black in females. Males and some females may have a faint orange-red stripe running over the medial keel; in both sexes some yellowish pigment may occur along the marginal seams. The plastron is elongated and notched posteriorly; the plastral formula is: abd > pect >< fem > gut ³ an > hum. Axillary scutes of the bridge are much smaller than the inguinals, and the bridge is narrower than the length of the posterior plastral lobe. In males, the plastron is yellowish with brown or black, irregularly shaped marks or streaks on each scute; females have dark brown to black plastra, often with substantial faded orange. The bridge is totally brown. The head is broad with a pointed, projecting snout. The medial, anterior profile of the upper jaw is concave, not straight, and the triturating surfaces are broad and ridgeless. The anterior dorsal surface of the head is smooth and scaleless, but the posterior surface is covered with small granular scales. In females and juvenile males, the head is greenish-black with narrow, soft yellow vermiculations. A yellow longitudinal stripe extends from the upper edge of the orbit over the tympanum to the neck on each side, and another below it extends from midorbit through the tympanum to the neck. The jaws are yellowish to tan with dark spotting. Limbs and tail are dark brown to black with some yellow scales on the forelimbs. Females become progressively darker with age. Sexually mature males develop a red nose and in most individuals the head becomes progressively red with black vermiculations. The yellow spots on the legs gradually turn red, expanding to the axilleries, inguinals and tail (De Bruin, 1993).
The karyotype is 2n = 52; 28 macrochromosome (18 metacentric or submetacentric, 10 telocentric or subtelocentric) and 24 microchromosomes (Carr and Bickham, 1986).
Except for distinct sexual dimorphism, males have longer, thicker tails with the vent beyond the carapacial margin.

Chinemys nigricans ranges from Guangdong Province, southern China, westward to northern Vietnam; possibly also on Hainan Island.

Geographic Variation
No subspecies are currently recognized; C. nigricans includes Geoclemys kwangtungensis Pope, 1934 (Iverson and McCord, 1989).

This is a species of the foothills, inhabiting streams at altitudes of 300-400 m (Pope, 1935).

Natural History
Pope (1935) reports this turtle lays a clutch of only two eggs. In captivity, a clutch consists of 2-9 brittle-shelled, oval (36-51 x 20-27 mm), white eggs (Ewert, 1979; Ron de Bruin, pers. comm.). Incubation lasts 51-55 days at 28-31°C. Plastron length of hatchlings is about 27 mm, and they weigh 4-6 g. Hatchlings have one medial and two indistinct lateral keels, and an orange to reddish plastron with some dark blotches progressively increasing in size to coarse, angular blotches or streaks (De Bruin, 1993; Peter Paul van Dijk, pers. comm.).
In captivity, Chinese red-necked pond turtles take beef, dry catfood, shrimp, squid, banana, tangerine, peach, and strawberry. Hatchlings are carnivorous (De Bruin, 1988; 1993).

IUCN Red List Status (1996)
Data deficient.