Fan, 1931
Okinawa black-breasted leaf turtle
Recognition
Formerly considered a subspecies of G. spengleri, G. japonica was elevated to full species rank by Yasukawa et al. (1992). Its elongated carapace is larger (to 16.3 cm) with three keels (the medial is best developed), and the anterior and posterior rims more bluntly serrated than in G. spengleri. The cervical scute is wedge-shaped and not posteriorly notched or only shallowly so. Vertebral scutes are broader than long. Pleurals and vertebrals with rugose growth annuli. The carapace is deep orange or yellow to reddish orange or dark brown. Some dark radiations or spots may be present, and dark lines or wedges extend along the keels. The large, elongated, hingeless plastron is shallowly notched posteriorly but more deeply notched anteriorly than that of G. spengleri. The plastral formula is pect >< abd >< an > fem >< hum >< gul. The short bridge has a distinct pair of axillary scutes, but the pair of inguinals are small and vestigial. The plastron and bridge are black or dark brown; the plastron has a light lateral border. Head with smooth dorsal surface. Head and neck are yellow to orangish yellow or reddish brown, with irregular reddish or yellowish lines or spots on the sides, snout and anterodorsal surface of the head. Small tubercles are present on the thighs near the tail.
The karyotype is 2n = 52 (Nakamura, 1949).
Sexual dimorphism is as in G. spengleri.
Distribution
Okinawajima, Kumejima and Tokashikijima islands of the Okinawa group of the central Ryukyus, Japan.
Geographic Variation
Unknown.
Habitat
According to Yasukawa et al. (1992) and Yasukawa and Ota (in press ), this species inhabits the forest floor of primary and well-developed secondary forests, often near mountain streams.
Natural History
Little has been reported regarding the life style of G. japonica. Four to six eggs (45.0-46.3 x 23.2-29.2 mm) are laid during the period April-August (Otani, 1989; Takara, 1969). The hatchling carapace is approximately 35 mm long.
G. japonica is omnivorous, feeding on plants, earthworms, snails and insects (Yasukawa et al., 1992).
IUCN Red List Status (1996)
Endangered (A1c, B1+2c).