Comparative cytogenetic studies of eleven species of the Tropidurus torquatus group (Sauria, Tropiduridae), with banding patterns

The chromosomes of 173 specimens representing eleven species of the Tropidurus torquatus group, from 33 localities in Brazil, were analysed after Giemsa staining, C-banding, NORs, and replication banding techniques. A karyotype with 2n = 36, including 12 macrochromosomes and 24 microchromosomes (12 M + 24 m), and sex determination of the XY:XX type were found in Tropidurus cocorobensis, T. erythrocephalus, T. etheridgei, T. hispidus, T. hygomi, T. montanus, T. mucujensis, T. oreadicus, and T. torquatus. The two other species, T. itambere and T. psammonastes, presented 2n = 36 (12 M + 23 m) karyotype only in females while males had 2n = 35 (12 M + 23 m), due to the sex determination of the X(1)X(2)Y:X(1)X(1)X(2)X(2) type. Other interspecific differences as well as some intraspecific variation regarding the NORs and C-banding patterns have been observed, mainly in the microchromosome set. on the contrary, the macrochromosomes were highly conservative. Although consistent karyotypic diversity occurred in the torquatus group, the cytogenetic data obtained up to now did not allow us to clarify the phylogenetic relationships of the species. Nevertheless, the geographical distribution of the distinct cytotypes in T. hispidus and T. torquatus suggested that more than one species might be involved in each case.