ULTRASTRUCTURE OF THE BASAL APPARATUS AND PUTATIVE VESTIGIAL FEEDING APPARATUSES IN A QUADRIFLAGELLATE EUGLENOID (EUGLENOPHYTA)

The flagellar apparatus and presumptive vestigial feeding apparatuses of a cold-water, photosynthetic, quadriflagellate euglenoid is describ ed. The organism possesses two similar sets of flagella each consistin g of one short and one long flagellum. Each pair of flagella is associ ated with three microtubular roots for a total of six roots in the bas al apparatus. At the level of the ventral basal bodies, each intermedi ate root is nine-membered, while the ventral roots are composed of eig ht to nine microtubules. Only one of the ventral roots lines the singl e microtubule reinforced pocket. A four-membered dorsal root attaches to each dorsal basal body, and at the level of the reservoir each give s rise to a dorsal band. An additional bundle of microtubules, not ari sing from the microtubular roots of the basal apparatus, begins poster ior to the basal apparatus as a small group of a few microtubules and extends anteriorly on the right ventral side of the reservoir ending a t the canal. At the level of the stigma, the microtubules are organize d into a multi-layered bundle that continues to increase in size and e ventually splits to form two bundles at the level of the canal. We pos tulate that these bundles may represent the remnants of a rod-and-vane -type feeding apparatus like that found in many phagotrophic euglenoid s.