Karyotypic description and comparison of Litoria (L.) paraewingi (Watson et al., 1971), L. ewingii (Duméril et Bibron, 1841) and L. jervisiensis (Duméril et Bibron, 1841) (Amphibia, Anura)

The karyotype of Litoria (L.) paraewingi (Watson et al., 1971) (Big River State Forest, Victoria) is described here for the first time. It is prepared following tissue culture of toe clipping macerates, cryopreservation, reculture and conventional 4',6-diamidino-2-phenylindole (DAPI) staining. The <i>L.paraewingi</i> karyotype is then compared to similarly processed IUCN (International Union for the Conservation of Nature) least concern members <i>L.ewingii</i> (Duméril et Bibron, 1841) (southern Victoria) and <i>L.jervisiensis</i> (Duméril et Bibron, 1841) (Myall Lakes National Park, New South Wales), all members of the same <i>L.ewingii</i> complex/group. The <i>L.paraewingi</i> diploid number is 2n = 26, the same as for the other two species. <i>Litoriaparaewingi</i> chromosomes 1, 2, 6 and 7 are submetacentric, chromosomes 3 and 5 are subtelocentric and the remainder are metacentric. No secondary constriction or putative nucleolus organiser region (NOR) was readily identifiable following conventional DAPI staining in any scored <i>L.paraewingi</i> metaphase spread. Conversely, a putative NOR was readily identifiable on the long arm of chromosome 1 in all examined metaphase spreads for the other two species. The karyotypes of <i>L.ewingii</i> and <i>L.jervisiensis</i> here further differ from <i>L.paraewingi</i> with chromosome 1 being metacentric and chromosomes 8 and 10 being submetacentric for both former species. The <i>L.jervisiensis</i> karyotype differs from those of <i>L.ewingii</i> and <i>L.paraewingi</i> by DAPI staining with: (i) apparent relative length inversion of subtelocentric chromosome 3 and metacentric chromosome 4 and (ii) chromosome 6 being metacentric rather than submetacentric. All three species have a highly conserved chromosome morphology with respect to chromosomes 2, 5, 7, 9, 11, 12 and 13. The greatest gross morphological difference karyotypically is observed between <i>L.paraewingi</i> and <i>L.jervisiensis</i>. These karyotype data support the previous phylogenetic separation of these three species based upon genetic compatibility and behavioural, biochemical and molecular genetic analyses.