The karyology of Vipera aspis, V. atra, V. hugyi, and Cerastes vipera

Abstract

AbstractIn the current paper we show the results obtained using standard and banding staining methods (Ag-NOR-, CMA3-, C-banding and sequential colorations (or Alu I digestions) + CMA3 + DAPI) in specimens of Cerastes vipera, Vipera aspis, V. atra, and V. hugyi. Cerastes vipera presented chromosomal characters, primitive in snakes, as a karyotype of 2n = 36 chromosomes, with 16 biarmed macrochromosomes and 20 microchromosomes, NORs on one microchromosome pair and absence of cytologically evident sex chromosomes, at least with the methods used. The three taxa of Vipera studied showed chromosomal characters either derived, or primitive or at an initial stage of differentiation. All three species showed a karyotype (derived) of 2n = 42 chromosomes with 22 macro- and 20 micro-chromosomes; they all showed NORs on one micro-chromosome pair and presented Z and W chromosomes at an initial stage of differentiation. Sexchromosomes Z and W, were in fact homomorphic, but the former was near all euchromatic, while the W chromosome was almost completely heterochromatic. All the three taxa of Vipera resulted, however, karyologically diversified, mainly due to the number of macro-chromosomes pairs with a centromeric, CMA3 positive heterochromatin: almost all the pairs in V. aspis, two pairs in V. atra and absent in V. hugyi.