FLAGELLATE SPORES IN HOMOEOSTRICHUS-OLSENII WOMERSLEY (DICTYOTALES, PHAEOPHYCEAE) - THE LARGEST KNOWN MOTILE REPRODUCTIVE CELLS OF MARINE MACROALGAE

The biflagellate spores of Homoeostrichus olsenii Womersley are the la rgest motile reproductive cells reported for any macroalga. They are a lso the first zoospores discovered in the Dictyotales and are consider ed to represent an intermediate stage in the evolution of the typicall y large non-flagellate dictyotalean spore from the small zoospores cha racteristic of most orders of the Phaeophyceae. Zoospores of H. olseni i have a large, elongate nucleus, basal bodies which are among the lon gest reported for algal motile cells and a conspicuous, fibrous, nucle us-basal body connector, a feature which is thus clearly demonstrated in the Phaeophyceae. The proximal ends of the basal bodies terminate c lose to the nucleus and the basal bodies consequently do not show the same orientation as most other phaeophycean motile cells.