Ultrastructure of the basal body complex and putative vestigial feeding apparatus in Phacus pleuronectes (Euglenophyceae)

Phacus pleuronectes (O. F. Muller) Dujardin is a phototrophic euglenoid wit h small discoid chloroplasts, a flat rigid body, and longitudinally arrange d pellicular strips. The flagellar apparatus consisted of two basal bodies and three flagellar roots typical of many phototrophic euglenoids but also had a large striated fiber that connected the two basal bodies and associat ed with the ventral root. The three roots, in combination with the dorsal m icrotubular band, extended anteriorly and formed the major cytoskeletal ele ments supporting the reservoir membrane and ultimately the pellicle. A cyto plasmic pocket arose in the reservoir/canal transition region. It was suppo rted by the ventral root and a C-shaped band of electron-opaque material th at lined the cytoplasmic side of the pocket. A large striated fiber extende d from this C-shaped band toward the reservoir membrane. The striated fiber s in the basal apparatus and associated with the microtubule-reinforced poc ket in P. pleuronectes appear to be similar to those of the phagotrophic eu glenoids.