Cytogenetic study of the Bent-toed Gecko (Reptilia, Gekkonidae) in Thailand; I: Chromosomal classical features and NORs characterization of Cyrtodactylus kunyai and C. interdigitalis

Abstract

This study analysed the karyotype of Cyrtodactylus kunyai and C. interdigitalis from Loei Province in Northeastern Thailand. The metaphase and meiotic chromosome preparations were obtained by squash technique from bone marrow and testes, respectively. The chromosomes were stained by Giemsa staining and Ag-NOR-banding techniques. The results showed diploid chromosome number (2n) of 40 for C. kunyai and 42 for C. interdigitalis. The chromosome types of metacentric, submetacentric, acrocentric and telocentric chromosomes were 8-4-0-28 and 4-2-4-32, respectively. The Ag-NORs banding technique provides the pair of nucleolar organizer regions (NORs) of both two species at telomeric region of the long arm of the pair 12, metacentric type in C. kunyai and telocentric type in C. interdigitalis. There are no sex differences in karyotypes between males and females of both two species. We found that during metaphase I on meiosis of C. kunyai and C. interdigitalis, the homologous chromosomes showed synapsis of 20 and 21 bivalents, respectively. Moreover, the meiotic phase on prophase II exhibited 20 and 21 haploid chromosome number (n) as respective diploid species. Their karyotype formulas is as follows: C. kunyai (2n = 40): L^m₂ + L^sm₄ + L^t₄ + M^t₆ + S^m₆ + S^t₁₈, and C. interdigitalis (2n = 42): L^a₄ + L^t₁₄ + M^t₂ + S^m₄ + S^sm₂ + S^t₁₆.