Karyotype characterisation of two Australian dragon lizards (Squamata: Agamidae: Amphibolurinae) reveals subtle chromosomal rearrangements between related species with similar karyotypes

Agamid lizards (Squamata: Agamidae) are karyotypically heterogeneous. Among the 101 species currently described from Australia, all are from the subfamily Amphibolurinae. This group is, with some exceptions, karyotypically conserved, and all species involving heterogametic sex show female heterogamety. Here, we describe the chromosomes of 2 additional Australian agamid lizards, Tympanocryptis lineata and Rankinia diemensis. These species are phylogenetically and cytogenetically sisters to the well-characterised Pogona vitticeps, but their sex chromosomes and other chromosomal characteristics are unknown. In this study, we applied advanced molecular cytogenetic techniques, such as fluorescence in situ hybridisation (FISH) and cross-species gene mapping, to characterise chromosomes and to identify sex chromosomes in these species. Our data suggest that both species have a conserved karyotype with P. vitticeps but with subtle rearrangements in the chromosomal landscapes. We could identify that T. lineata possesses a female heterogametic system (ZZ/ZW) with a pair of sex microchromosomes, while R. diemensis may have heterogametic sex chromosomes, but this requires further investigations. Our study shows the pattern of chromosomal rearrangements between closely related species, explaining the speciation within Australian agamid lizards of similar karyotypes.