Structure and position of bacterial endosymbionts in the gill filaments of lucinidae from bermuda (Mollusca,Bivalvia)

Summary The gills of four lucinid bivalves from fine sediments in shallow reaches of Bermuda, Anodontia philippiana, Lucina multilineata, L. radians, and L. costata, were observed by electron microscope. They harbour intracellular bacterial endosymbionts similar to those in gills of clams from hydrothermal vents and other sulphide biotopes. The bacteria-containing bacteriocytes are found in distinct positions in the gill filaments, alternating with cells not invaded by the prokaryotes but with abundant mitochondria. Referring to the specific environment of the collected bivalves and to literature data from corresponding studies, the significance of this bacteria/animal association is discussed.