CHROMOSOMES AND THEIR MEIOTIC BEHAVIOR IN 2 FAMILIES OF THE PRIMITIVEINFRAORDER DIPSOCOROMORPHA (HETEROPTERA)

Five species belonging to the two families or Dipsocoromorpha were stu died: three species from the family Dipsocoridae - Cryptostemma pusill imum J. Sb. (2n = 16 + 2m + XY(1)Y(2)), C. hickmani Hill (2n = 18 + 2m + XY), and C. castaneovitreus Linnavuori (2n = 18 + m? + XY) and two species from the family Schizopteridae Pateena elimata Hill (2n = 30 2m + X0) and Rectilamina australis Hill (2n = 30 + 2m + X0). In all s pecies, autosomes formed chiasmate bivalents in spermatogenesis, and t he sex chromosome univalent(s) divided at the first meiotic division a nd segregated at the second. The evolution of autosomal number, m-chro mosomes, and sex chromosome systems within the Dipsocoromorpha and in the whole Heteroptera was discussed.