A Cytogenetical Study on the Genus

[[abstract]]Five known species of Japalura lizards are found in Taiwan, including J. swinhinis, J. brevipes, J. makii, J. luei, and J. polygonata xanthostoma. Great variation have been found among inter- and intra- species, however, no cryptic specie can be detected based on their morphologies, mitochondria RFLP and 12S rRNA except for the chromosome data. Cytogenetic analysis is proved to be useful in establishing animal phylogeny, especially in the identification of Japalura. The present study focus on building reconstructing the phylogenetic relationships of all Japalura including new cryptic species found in Taiwan via cytogenetical approaches. Seven species including two new species of Japalura lizards from Taiwan were successfully karyotyped. One new specie is Japalura sp. 1 distributed in the low mountains in Taichung and Nantou Counties, another is Japalura sp. 2 distributed in the Hsueshan Mountain Range. Chromosome numbers of Japalura sp. 1 and Japalura sp. 2 are 2N = 46 and 36, respectively. The sex-determining mechanism of J. sp. 1 is ZZ/ZW type, and the others have no sex chromosome. The C-bands of chromosomes in all Taiwanese Japalura lizards studied are not successfully stained thus is not included in the present study. There is only one pair of Ag-NORs in the karyotypes that are located at the distal end of the 18th pair in Japalura swinhonis and J. brevipes, the 13th pair in J. makii and J. luei, the 21th pair in J. p. xanthostoma, the 14th pair in J. sp. 1 and the 17th pair in J. sp. 2. The macrochromosomes of all taxa showed remarkable G-bands that are species specific. Karyotypic patterns among four out of seven species, Japalura brevipes, J. makii, J. luei and J. sp. 2, are relatively similar, especially in the 1st and 2nd pairs of chromosomes, that infers the close relationship among these four species. Japalura brevipes and J. sp. 2 have more similar banding patterns and are more closely related. Two hypothesis about evolutions of the genus Japalura from Taiwan are proposed according to cytogenetic analysis. The fusion hypothesis proposed the present karyotypes with low diploid chromosome numbers and high biarmchromosome numbers were derived from a primitive karyotype with 2N = 46 and all telocentric chromosomes by Robertsonian fusions, while the fission hypothesis derived from a primitive karyotype with 2N = 36 that are suspected to Robertsonian fissions to form the present karyotypes. All the morphological data, the ribosomal 12S rRNA, and the present NORs-carrying marker chromosomes support the fusion hypothesis and against the fission hypothesis. In summary, the Japalura species in Taiwan can be separated into two sister clusters: the Japalura swinhonis group (J. swinhonis and J. sp. 1) and the Japalura polygonata group (J. p. xanthostoma, J. makii, J. luei, J. brevipes, and J. sp. 2).