A new species of marine labyrinthulid Labyrinthuloides yorkensis gen. nov. spec. nov. —Cytology and fine structure

Summary The structure and life cycle of a new genus and species of labyrinthulid, Labyrinthuloides yorkensis, is described from observations of pure cultures. Uninucleate cells are capable of gliding by means of ectoplasmic nets which push or pull the cells across the substrate. The net elements do not enrobe the cells and motility is reversible. Sporulation occurs by successive bipartition or progressive cleavage of the protoplast. Biflagellated zoospores with an anterior tinseled flagellum and posterior whiplash flagellum are formed as are non-replicating amoebae and plasmodia. The fine structure includes centrioles with a single large granule in the lumen and numerous cytoplasmic inclusion bodies with associated membrane complexes. The membrane-inclusion arrays are each found within a delimiting vesicle membrane.Contribution No. 503, Virginia Institute of Marine Science, Gloucester Point, Virginia 23062.Supported in part by the Oceanography Section, National Science Foundation NSF Grant GA-31014.