Indonesia is a tropical country which has varies of habitat types that are dispersed into thousands islands. The diversity and its tropical climate, makes Indonesia as a suitable place as a natural habitat for herpetofauna, especially Sub Order Serpentes. Xenochrophis vittattus (Linnaeus, 1578), called stripped keelback snakes, is a semi-aquatic snakes spread in Indonesia, especially in Java, Sumatra, Bangka, and Manado, and commonly used as pet. Since there are few reports on genetic studies, especially in the field of karyology, this study aims to characterize the chromosomes of stripped keelback from Piyungan population, Bantul, Yogyakarta. This study used a brief splash of blood cultures method. This has been known as the first stripped keelback cytological study in Indonesia. The results showed that striped keelback has a diploid chromosome (2n) = 34, consists of metacentric chromosome (number 1, 2, 3, 4, 19, 20, 21, 22, 23, 24, 25, and 26); submetacentric chromosome (number 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, and 18). Whereas the chromosome number 27, 28, 29, 30, 31, 32, 33, and 34 were micro chromosomes. Striped keelback karyotype formula was 2n = 2x = 34 = 12 m 14 sm 8 micro chromosomes. The longest chromosome of stripped keelback was 2.9335 ± 0.1772 um, whereas the shortest one was 0.5088 ± 0.013 um, and the R value was 5.9106 ± 1.1265.

Keywords: Xenochrophis vittattus, Stripped keelback, chromosome characterization, karyotype

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