Karyological Analysis of the Indo-Chinese Water Dragon, Physignathus cocincinus (Squamata, Agamidae) from Thailand

Karyological analysis of the Indo-Chinese water dragon (Physignathus cocincinus) from Northeast Thailand was studied. Dragon lizard chromosome preparations were conducted by a squash technique from bone marrow and testis. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosome with Giemsa's solution. The results showed that the number of diploid chromosome was 2n=26, while the fundamental number (NF) were 48 in both males and females. The types of chromosome were five metacentric pairs and one submetacentric pair of macrochromosomes, and 12 pairs of apparent microchromosomes. No irregularly sized chromosomes related to sex were observed. Nucleolar organizer regions (NORs) are located at the secondary constriction of the long arm near telomere in macrochromosome pair 2. We found that during metaphase I the homologous chromosomes showed synapsis, which can be defined as 18 bivalents and 18 haploid chromosomes at metaphase II as in diploid species. The karyotype formula is as follows: 2n (36)=L-4(m)+L-2(sm)+M-4(m)+S-2(m)+24 microchromosomes.