Chromosome studies on Dasypus, Euphractus and Cabassous genera (Edentata: Dasypodidae)

The somatic and meiotic chromosomes of twenty specimens of the Dasypodidae were studied. The wild specimens belonged to the genera Cabassous, Euphractus and Dasypus. The karyotype of D. novemcinctus showed a diploid chromosome number of 64, although some variation was observed in one specimen where 2n was 65, due to a supernumerary chromosome, and another had a dimorphic pair. D. septemcinctus also had a diploid chromosome number of 64, and showed two variant types due to pericentric inversions and/or centric fusions. E. sexcinctus and C. unicinctus had diploid chromosome numbers of 58 and 50, respectively. These species did not show variant chromosome types, and this was confirmed in meiotic studies. Analysis of the meiotic epithelium of species of Dasypus including the analysis of the synaptonemal complex in pachytene nuclei, showed similar findings to those commonly reported in mammalian meiosis, especially in relation to pairing and formation of the sex bivalent. The evolutionary implications of the chromosome changes in relation to organic evolution are discussed.