CONICET | Buscador de Institutos y Recursos Humanos

The genus Graomys contains four species and presents significant karyological25 diversity. Graomys griseoflavus, inhabiting mainly the Monte Desert ecoregion, shows26 variation in diploid number (2n) from 33 to 38 due to Robertsonian translocations, and in27 fundamental number of autosomal arms (FNa) from 44 to 48 due to inversions. Graomys28 chacoensis, which occurs in the Chaco and the Espinal ecoregions, has 2n=42 and FNa=4429 46 due to a pericentric inversion. Graomys domorum, which inhabits the Yungas ecoregion30 and Yungas-Chaco transitional zones, exhibits 2n=28 and FNa=46, but its karyotype is only31 known by a schematic representation for two specimens from Bolivia. The karyotype of G.32 edithae has not been described yet. In this report, we studied 29 individuals of the three33 former species, from different localities of their distribution, using conventional and34 differential cytogenetic techniques and chromosome measurements. In G. griseoflavus, we35 identified the pairs involved in the three Robertsonian translocations, supporting an36 independent, not sequential origin of this polymorphism. The nearby area of Mendoza City37 exhibited the greatest chromosomal diversity for G. griseoflavus. The banding pattern38 associated with chromosomal measurements allowed us to suggest the possible pairs involved39 in the pericentric inversions of G. griseoflavus and G. chacoensis. The presence of40 heterochromatin indicates more significant chromosomal variability and complexity than41 previously recognized. The chromosome complements of G. chacoensis and G. griseoflavus42 are more similar. The karyotype of G. domorum from Argentina differed from the previously43 reported in Bolivia, and it is the most divergent within the genus.

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