ULTRASTRUCTURE OF TROPHOZOITES, ZOOSPORES AND CYSTS OF RECLINOMONAS-AMERICANA FLAVIN AND NERAD, 1993 (PROTISTA-INCERTAE-SEDIS, HISTIONIDAE)

Several previously-unreported features of Reclinomonas americana are d escribed from light and electron microscopical observations. Golgi app aratuses were found in trophozoites and zoospores, as were ejectosomes and inclusion bodies. Scale-bearing vesicles were present in zoospore s but not trophozoites, and zoospores lacked epipodia. No vane was pre sent on the posterior flagellum of zoospores. Cysts were formed only i n mineral media with added bacteria; they did not appear in infusion m edia. Kinetids in trophozoites and zoospores, reconstructed from seria l sections, consisted of two basal bodies, a dorsal fan of secondary c ytoskeletal microtubules, and three ventral microtubular roots, the le ftmost of which had a multilayered structure at its proximal end. Ultr astructural features suggest that the genera Reclinomonas and Jakoba a re sister taxa, and that the nearest relations to these two genera are the retortamonads, an amitochondriate archezoan group.