Fleabeetles of the subtribe Oedionychina fall in two phylogenetic categories in relation to the structure of the nuclear envelope, and of the epinuclear material synthesized in the diffuse stage of spermatocyte I. Omophoita shows a plain envelope surrounded by a continuous sheath of epinuclear material, whereas Oedionychus and related genera show a rough envelope with cup-like nuclear sieve complexes, and a discontinuous epinuclear material. The epinuclear material has no part in breaking down the nuclear envelope, which is wrinkled and squashed against the cell wall by aster action. The envelope does not wholly disappear until the prometaphasic congression. Released, empty nuclear sieves form a swarm at the surface of the M I spindle, and can be sometimes recognized still in the M II spindle. No interkinetic nucleus forms. The unique structure of nuclear envelope of Oedionychus suggests a more advanced evolutionary status as compared with Omophoita, a genus having some karyotypic affinities toward the sister subtribe Disonychina.