PERSISTENCE OF CELL DIVISION SYNCHRONY IN Prorocentrum triestinum (DINOPHYCEAE) . – Prorocentrum triestinum shows a long time persisting circadian rhythm in cell division. The light-dark cycle synchronizes their cell division and this synchrony persist about 8 cycles under continuous light. Anyone of the previous stochastic or deterministic chronobiological models can not explain this persistence of cell division synchrony because neither inter-cells communication nor the similarity of free-running cell cycle period among cells maintain the synchrony. A inter-generational transmission of synchronizing information maintain this persisting circadian rhythm.