Codosiga minima n. sp. strain IOW73. Light (A) and transmission electron (B-G) micrographs. A. Single cell and two-cell colony with a stalk (st), living material under phase contrast. B. Longitudinal section of the cell, arrowheads show a delicate sheath around the cell body and proximal part of collar microvilli (mv). Insert upper right: transversal section through the collar with food vacuole (fv) with bacterium at outer side of the collar. Insert down left: two mitochondrial profiles with tube-like cristae (arrows). C. Longitudinal section of feeding cell in the colony: pseudopodium (ps) arises from the neck. D. Longitudinal section of flagellar kinetosome (kn) with one row of radiating microtubules (arrows). Scale bars in A = 4 μm, B (+ upper insert), C = 2 μm, B (down insert), D = 500 nm.