Are chromosomal axial struc-ures and microtubular systems phylogenetic markers in the dinoflagellates?

Two new events concerning nuclear division and chromosomal predivision are described in the free-living marine dinoflagellate Prorocentrum micans E. considered by Loeblich (1976) as a primitive form. These events will be discussed in relation to the evolution of Dinoflagellates. (1) Presence of a paranuclear bundle of microtubules parallel to the extranuclear bundle passing through the dividing nucleus (Soyer, 1975, 1977b) and (2) Presence of a chromosomal axis in the predividing chromosomes (Soyer, 1977c).