Karyotypic diversity of the genus Graomys Thomas, 1916 (Rodentia, Cricetidae, Sigmodontinae)

ROMINA DE CENA; CAROLINA LABARONI; JUAN JOSE MARTÍNEZ; JUAN DIEGO BALDO; LUIS IGNACIO FERRO; AGUSTINA OJEDA; DANIELA RODRIGUEZ; CECILIA LANZONE

MASTOZOOLOGí­A NEOTROPICAL

UNIDAD DE ZOOLOGÍA Y ECOLOGÍA ANIMAL, INSTITUTO ARGENTINO DE INVESTIGACIÓN DE LAS ZONAS ARIDAS, CRICYT, CONICET

Lugar: Mendoza; Año: 2023 vol. 30

0327-9383

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