The karyo types of five turtles of the genus Podocnemis from the Amazon Region of Brazil were determined. Four species, P. cayennensis, P. expansa, P. sextuberculata and P. unifilis have 28 (2n) chromosomes and one, P. dumeriliana, has 26 (2n). No morphologically distinguishable sex chromosomes could be observed. The difference in number in P. dumeriliana can be explained by the occurrence of a centric fusion. The chromosome numbers in this genus are extremely low when compared with the range previously found in Chelonia (2n = 50 to 64).
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