Non-random segregation during anaphase II in an individual of Arcyptera tornosi (Bol.) (Orthoptera) heterozygous for three supernumerary heterochromatic segments

An individual of Arcyptera tornosi heterozygous for distal heterochromatic segments affecting M₆, S₁₀ and S₁₁ chromosomes has been analyzed during all the meiotic stages in order to establish the pattern of meiotic segregation in anaphase I and II. S-bivalents invariably show an equational separation during anaphase I and the anaphase II separation is non-random, both chromatids with heterochromatic segments often segregating to the same pole. Differences are significant if compared with the expected segregation. Some aspects of this particular chromosome behaviour are briefly discussed.