Fitzinger, 1835
Neotropical wood turtles
Recognition
The eight members of the genus Rhinoclemmys are semitropical and tropical American turtles that frequent aquatic, semi-aquatic, and terrestrial habitats. They are the only turtles of the subfamily Batagurinae to occur in the New World. The carapace is low arched to domed, and medially keeled. Each neural is hexagonal and projects behind its associated lateral costal bones. The plastron is rigid, well-buttressed, and lacks a hinge. The skull is short, and flattened to slightly convex dorsally with lateral orbits. Frontals form part of the orbital rim. The quadrate does not enclose the stapes; the otic notch is open. The dorsal surface of the tympanic bulla is ridged. The squamosal is only loosely attached; is either separated from the parietal or meets it posterolateral to the trigeminal foramen; barely, if at all, touches the jugal; and is in contact with the postorbital. The parietal is separated from the jugal but touches the palatine. The jugal is broadened posteriorly. The zygomatic arch is absent or, if present, is narrow and excavated dorsally and ventrally. Triturating surfaces of the maxillae are narrow and ridgeless. Toes may or may not bear webbing.
The karyotypes of the species areolata, funerea, melanosterna, pulcherrima, punctularia, and rubida have been determined (Barros et al., 1975; Bickham and Baker, 1976b; Killebrew, 1977a; Bickham and Carr, 1983, Carr and Bickham, 1986). The species areolata, funerea, melanosterna, pulcherrima, and rubida have nearly identical karyotypes to the presumed primitive 2n = 52, but the nucleolus organizer regions (NOR) are in a slightly different position than in Asiatic batagurines with 52 chromosomes. R. funerea differs from the others in having 8 metacentric or submetacentric macrochromosomes instead of the usual 9. R. punctularia is 2n = 56, having 2 extra pairs of heterochromatic microchromosomes, and 8 metacentric or submetacentric macrochromosomes.
Species identification
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