• chloroplast retention;
  • Chroomonas;
  • Cryptophyta;
  • Gymnodinium acidotum;
  • Gymnodinium aeruginosum;
  • phagotrophy;
  • Pyrrophyta


Gymnodinium acidotum Nygaard, a blue-green dinoflagellate previously shown to contain cryptophycean chloroplasts and other organelles, was observed from water and soil samples and in culture. The dinoflagellate excysts from soil samples as a mononucleated colorless cell that is positively phototactic. Colorless cells in unialgal culture remain colorless and can only be maintained less than one week whereas pigmented cells cultured unialgally grow for 10 days but then decline rapidly. Colorless cells cultured with Chroomonas spp. regain chloroplasts and have been maintained in mixed cultures for nine months. Fifty-seven percent of the dinoflagellates from mixed cultures are bi-nucleated, and three cells have been observed possibly ingesting cryptophytes. We suggest that cryptophycean chloroplasts are retained and possibly utilized by G. acidotum for at least ten days and then digested.