Orlitia borneensis

Gray, 1873b
Malaysian giant turtle

This large (to 80 cm) semi-aquatic turtle has a narrow, oval carapace which is relatively high peaked in the young at the area of the seam separating the 2nd and 3rd vertebrals. Adults are somewhat flatter. The vertebrals bear a low medial keel, at least in juveniles, and appear narrow when compared to the adjacent pleural scutes. The 2nd vertebral is always somewhat "mushroom" shaped with the stalk pointing backward. The underlying neural bones are elongated, hexagonal, and short sided anteriorly. The anterior neurals are much narrower than those to the rear. Posterior marginals are strongly serrated in juveniles, but less so in adults, and are smaller than the lateral or anterior marginals. Pleural 4 is considerably smaller than the first three. All carapacial scutes are somewhat rugose. The carapace is uniformly dark gray, brown, or black. The plastron is long and narrow, with an anal notch. Lateral plastral margins may be keeled. Both the anterior and posterior lobes are much narrower than the pectoral and abdominal scutes. The humero-pectoral seam lies posterior to the entoplastron. The plastral formula is: abd > pect > fem > gul > hum >< an. The bridge contains both axillary and inguinal scutes and is much longer than the posterior plastral lobe. The plastron is sutured to the carapace and the buttresses are strongly developed. Axillary buttresses are attached to the 1st ribs; inguinal buttresses insert over half the distance up the suture between the 5th and 6th costals. Bridge and plastron are yellowish to light brown, and usually unmarked. The head is relatively large and broad with a slightly projecting snout. The upper jaw is slightly hooked and its triturating surface is broad posteriorly, with a well-developed medial ridge, but narrow medially. In the skull, the squamosal is firmly attached to the surrounding bones and extends anteriorly. The orbito-nasal foramen is large (much larger than the posterior palatine foramen). A strip of granular scales lies between the orbit and tympanum, and the skin on the back of the head is broken into small scales. The adult head is uniformly brown or black; that of juveniles may be dark mottled and have a light line extending backward from the corner of the mouth. Neck, limbs, and tail are gray, brown, or black. The forelimbs have large horizontal scales on their anterior surface. All toes are webbed.
Bickham (1981) and Carr and Bickham (1986) reported the diploid chromosome total to be 50; 26 macrochromosomes (16 metacentric or submetacentric, 10 telocentric or subtelocentric) and 24 microchromosomes.
Males have longer, thicker tails than do females.

This highly aquatic species is known only from Malaysia, Sumatra, and Borneo.

Orlitia apparently occurs in large bodies of fresh water, such as lakes and rivers.

Natural History
Little is known of the biology of this apparently rare turtle. Aborigines told Dr. Edward Moll that Orlitia nests in piles of debris, but he did not personally observe this. Its eggs are ellipsoidal with brittle shells, averaging about 80 x 40 mm. Hatchlings are about 60 mm long and have very rugose carapaces with strongly serrated posterior marginals.
Mehrtens (1970) reported that a captive accepted a variety of protein foods such as beef heart, horsemeat, canned dog food, and fish. It also accepted overripe bananas, but refused other vegetables. Food was taken as readily on land as in the water.

IUCN Red List Status (1996)
Lower risk: near threatened.