THE FLAGELLAR APPARATUS OF PRYMNESIUM-NEMAMETHECUM (PRYMNESIOPHYSCEAE)

The flagellar apparatus of Prymnesium nemamethecum Pienaar et Birkhead is more similar to that of P. patelliferum Green, Hibberd et Pienaar than to any other prymnesiophyte yet described. This includes the arrangement of the appendages, the origins and pathways of the microtubular roots, and the system of fibrous and striated connectives. There is, however, a major difference in the presence of a compound broad root in interphase cells of P. nemamethecum. Other differences include the number of constituent microtubules in some roots, the extent of development of a root (herein designated R7) associated with the right basal body, and an additional accessory band (AB3) in P. nemamethecum. The transitional region of the flagella is also described. It resembles that of P. parvum Carter, as both species have two transitional plates separated by a form of stellate structure. P. nemamethecum also has a distal axosome and a series of tubular rings between the outer doublets and the flagellar membrane. The transitional regions of both species are very different from those described in the Isochrysidales and the Coccosphaerales.