(Siebenrock, 1906b)
Wattle-necked softshell turtle
Recognition
The oval (longer than broad) carapace (to 42.6 cm) has numerous longitudinal rows of small, raised tubercles in younger individuals; the carapacial surface becomes more nearly smooth with age. There is a well-defined marginal ridge along the anterior rim of the carapace, and on it are enlarged, blunt tubercles. No preneural bone is present and only a single neural bone separates the most anterior of the eight pairs of costals; the 8th pair meets at the midline. Carapacial bones are pitted. Adult carapaces are brown, olive brown, or gray brown, and patternless. The yellow to cream or grayish plastron usually lacks dark markings. It has callosities on the hyo- and hypoplastra, xiphiplastra, and epiplastra. The long anterior extensions of the epiplastra are in contact. The entoplastron forms right angles to the plastral midline and has pointed branches. There is usually a suture between the hyo- and hypoplastra. The skull is moderate in size with a bony snout which is slightly longer than the greatest diameter of the orbit. No symphysial ridge occurs on the mandible, and the width of the symphysis is less than the greatest diameter of the orbit. Head and limbs are olive to brown. There are black preorbital, suborbital, and postorbital streaks, and shorter black streaks and dots on top of the head. A pale yellow stripe begins behind the eye and runs backward on the side of the neck, becoming narrower as it proceeds toward the body. A yellowish spot also occurs at the corner of the jaws. Head and neck markings are lost with age. At the base of the neck is a large clump of coarse tubercles (wattles) which is diagnostic for the species. A lateral ridge projects from each side of the nasal septum.
Lin et al. (1988) reported that the karyotype of this species is composed of 66 chromosomes, including 44 macrosomes (8 metacentric, 8 submetacentric, 24 telocentric, 4 subtelocentric) and 22 microchromosomes.
Males are smaller than females and have longer, thicker tails with the vent closer to the tip.
Distribution
Palea steindachneri ranges in China from Guangdong, Guangxi, and Hainan Island southwestward into northern Vietnam. It has been introduced and is now established on the islands of Kauai and Oahu, Hawaii (Webb, 1980b; McKeown and Webb, 1982) and Mauritius (Bour, 1985).
Geographic Variation
Unknown.
Habitat
In Hawaii this softshell occurs in marshes and drainage canals. It is found to an altitude of 1500 m in Tongking, China (Pope, 1935).
Natural History
The sparse life history data known for Palea steindachneri were reported by McKeown and Webb (1982). Nesting in Hawaii probably occurs in June, and hatching in late August or September. Clutch size varies from 3 to 28, and the spherical (22 mm in diameter) eggs have brittle shells. Hatchlings have rounded carapaces (54-58 mm) which are orangish brown with scattered black spots. The longitudinal rows of tubercles on the carapace are prominent, as also are the dark head stripes and yellow neck stripe.
Both juveniles and adults are primarily carnivorous. Captives at the Honolulu Zoo have eaten fish, raw beef, horse meat, chicken parts, mice, crickets, crawfish, mollusks, amphibians, and some plant materials. The basking habit is poorly developed in adults, although juveniles may venture onto land.
Remark
According to Meylan (1987), the wattle-necked softshell turtle is most closely related to the species Dogania subplana and Pelodiscus sinensis.
The specific name, Aspidonectes californiana Rivers, 1889, attributed to a softshell from the Sacramento River, California, is a senior synonym of Palea steindachneri (Webb, 1975). Since the seldom-used name californiana has priority over the better known steindachneri, Webb (1978) petitioned the International Commission of Zoological Nomenclature (ICZN) to use its plenary powers to suppress californiana and place it on its Official Index of Rejected and Involved Specific Names in Zoology. This the ICZN did in 1982.
IUCN Red List Status (1996)
Lower risk: near threatened.