Genus Kachuga

Gray, 1856
Indian roofed turtles

This is one of the largest genera of Asiatic Bataguridae with seven species from Pakistan, India, Bangladesh, and Myanmar. All are semi-aquatic, and some reach 50 cm in length. The elongated, oval carapace is high arched with a single, medial vertebral keel, which has posteriorly pointing projections in several species. Neurals are usually hexagonal in shape and short sided anteriorly; although the fourth is octagonal in K. tecta, K. tentoria and K. sylhetensis. Vertebral 4 is much longer than broad, and covers parts of four or five neurals (only three in Callagur). The plastron is rigid, lacking a hinge. Its buttresses are large; the axillary contacts the 1st rib while the inguinal extends upward to about the midpoint of the suture between the 5th and 6th costals. The entoplastron lies anterior to the humero-pectoral seam. On the skull, the temporal arch is usually complete, the quadratojugal touches both the jugal and postorbital. The inferior temporal emargination is deep; the maxilla is excluded from the squamosal. Posterior temporal emargination is also deep; the frontal bone is excluded from the posterior temporal emargination by the parietal and postorbital bones. The squamosal prevents contact between the postorbital and the supratemporal bones. The triturating surface of the maxilla is broad and contains a single median denticulated ridge; the edges of the jaws are also serrated. The maxilla is prevented from touching the inferior parietal process by the palatine. The orbito-nasal foramen is large, and the pterygoid does not extend to the articular surface of the quadrate. The toes are webbed.

Moll (1986) resurrected the subgenera Kachuga and Pangshura of Gray (1856). The species assigned to the subgenus Kachuga (dhongoka, kachuga, trivittata) have the upper jaw either medially notched or weakly bicuspid, a carapace length over 40 cm, an unstriped or three striped carapace which is highest on vertebral 2, projections on the vertebral keel only in hatchlings, the 4th vertebral anteriorly broad and lying over four neural bones, and prominent peripheral-costal fontanelles in males. The other species (smithii, sylhetensis, tecta, tentoria) assigned to Pangshura have an unnotched, non-cuspid upper jaw, a carapace length less than 30 cm long, a medially striped carapace which is highest on vertebral 3, the 4th vertebral anteriorly narrow and lying over five neural bones, and the peripheral-costal fontanelles fused or reduced to very small openings by maturity.

Species identification
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