[New data on non-parallel evolution of karyotype and morphology in Phyllotinae (Rodents, Cricetidae)].

The non-concordance of the morphological and chromosomal evolution in the Phyllotinae is discussed in the light of the latest karyological data concerning the genus Zygodontomys: individual specimens of this genus from French Guiana present a new chromosomal formula with a high number 2 N; their karyotypical and morphological peculiarities are sufficient to warrant creating a new species Z. reigi. The great variability of the karyotypes appearing in this genus permits one to think that the various groups could represent successive aspects of the same chromosomal evolution, an increase of the number 2 N preceding an eventual decrease.