FINE-STRUCTURE OF THE MARINE DIATOM PLAGIOGRAMMOPSIS-PANDURIFORMIS, SPEC-NOV (CYMATOSIRACEAE)

Based on a clonal culture a new centric diatom, Plagiogrammopsis pandu riformis, is described. Though lacking the typical pill, all other rel evant structural features correspond with the generic diagnosis. The c ells containing a single large chloroplast are loosely united to form chains. The valves are panduriform in outline and traversed by a pseud oseptum in the middle. The elevated valvar poles bear ocelluli. The va lve is perforated by irregularly arranged areolae except for the fasci a with the pseudoseptum. The labiate process, one per cell, is located submarginal close to the pseudoseptum. Ultrathin sections reveal fine structural details of the protoplast and cell wall.