ULTRASTRUCTURE OF THE FLAGELLAR APPARATUS OF NOCTILUCA-MILIARIS SURIRAY SWARMERS (DINOPHYCEAE)

The swarmers of Noctiluca miliaris Suriray are not uniflagellate, as w as assumed for more than a century, but are biflagellate cells. Their flagellar apparatus displays two distinctly heteromorphic flagella: a long flagellum extending posteriorly (=longitudinal flagellum) and a v ery short flagellum oriented to the cells left side (=transverse flage llum). The transverse flagellum is situated in a groove and is therefo re not visible in the light microscope. A serial section analysis of t he basal apparatus of the swarmers reveals structures which are typica l for dinoflagellates including a posteriorly directed microtubular ro ot (pmr) and a ventral ridge with microtubular and fibrous components (vrm and vrf). Striated fibrous roots are, however, lacking. The struc turally relatively simple flagellar apparatus of N. miliaris swarmers may reflect their functional specialization as (micro-)gametes.