Gutiérrez J M, Solórzano A, Cerdas L
Rev Biol Trop. 1984 Nov;32(2):263-7.
The karyotypes of five species of colubrid snakes from Costa Rica are as follows: Imantodes cenchoa and Drymobius margaritiferus have a diploid number of 36, with 16 macro- and 20 microchromosomes. The fourth pair is heteromorphic in females of I. cenchoa, with a metacentric Z and a submetacentric W chromosomes. Karyotypes of Erythrolampius bizonus and Leimadophis epinephalus have 28 chromosomes, without a clearcut separation between macro- and microchromosomes. In the case of E. bizomus, the fourth pair contains the sex chromosomes Z and W, both are submetacentric, but the W is smaller. Xenedon rabdocephalus has a diploid number of 34 chromosomes (22 macro- and 12 microchromosomes); pair 3 is heteromorphic in females, with a submetacentric Z and a smaller metacentric W. The karyotype of X. rabdocephalus may be derived from a primitive karyotype by means of reduction in the number of microchromosomes and centric fissions of two pairs of metacentric autosomes.
伊氏锦蛇（Imantodes cenchoa）和珠斑锦蛇（Drymobius margaritiferus）的二倍体数目为36，有16条大染色体和20条小染色体。在伊氏锦蛇的雌性个体中，第四对染色体异形，有一条中着丝粒的Z染色体和一条亚中着丝粒的W染色体。红纹锦蛇（Erythrolampius bizonus）和后鳞锦蛇（Leimadophis epinephalus）的核型有28条染色体，大染色体和小染色体之间没有明显区分。在红纹锦蛇中，第四对染色体包含性染色体Z和W，二者均为亚中着丝粒，但W染色体较小。黑首锦蛇（Xenedon rabdocephalus）的二倍体数目为34条染色体（22条大染色体和12条小染色体）；在雌性个体中，第三对染色体异形，有一条亚中着丝粒的Z染色体和一条较小的中着丝粒W染色体。黑首锦蛇的核型可能是通过减少小染色体的数目以及两对中着丝粒常染色体的着丝粒裂变，从原始核型演变而来。
