Transmission electron micrographs (TEM) showing the ultrastructure of putative primary endosymbionts in Auranticordis quadriverberis n. gen. et sp. A. Low magnification TEM showing four putative endosymbionts, each surrounded by sac-like vesicles (sc) defined by an outer membrane (Bar = 2 μm). B. High magnification TEM showing two enveloping inner membranes (arrowheads) and thylakoids (arrows) that are continuous with the innermost enveloping membrane (Bar = 0.2 μm). C. TEM showing the thylakoids, the sac-like vesicle (sc), and a cleavage furrow indicative of division (arrowheads) (Bar = 0.5 μm). D. High magnification TEM showing the central core of an endosymbiont containing viral particles (arrowheads) (Bar = 0.5 μm). E. High magnification TEM showing a pronounced invagination of the innermost enveloping membrane (arrowhead) (Bar = 0.5 μm). F. High magnification TEM showing the membrane (arrowheads) that defines the sac-like vesicle (sc) and the two innermost enveloping membranes (double arrowheads) (Bar = 0.2 μm). G. TEM showing viral particles (arrowhead) consisting of a polygonal head and tail, and positioned within the core of an endosymbiont (Bar = 0.5 μm). An inset showing a complete tailed viral particle (Bar = 0.2 μm).