Codosiga balthica n. sp. strain IOW94. Light (A) and transmission electron (B-G) micrographs. A. Single cell on the stalk (st), living material under phase contrast. Arrowheads show the whiskers. B. Longitudinal section through the cell covered with delicate sheath (arrowheads); insert: enlarged mitochondria of class 1 (m1) with tubular/saccular cristae. C. Cytoplasm at cell posterior filled with endobiotic bacteria. D–E. structure of large flagellated bacteria with flagellar at cross section (D) and longitudinal section (E). F. mitochondria class 1 (m1) with tubular/saccular cristae. G. mitochondria class 2 (m2) structure with tubular cristae and lipid globule association with bfb. Scale bars: A – 3 μm, B – 1 μm, C-F – 200 nm, G – 400 nm.