Schematic reconstruction of the mature spermatozoa of Tergestia clonacantha and T. laticollis. Aae1 = anterior extremity of the first axoneme, Aae2 = anterior extremity of the second axoneme, Ase = anterior spermatozoon extremity, A × 1 = first axoneme, A × 2 = second axoneme, Az = attachment zone, Cm = cortical microtubules, Eo = external ornamentation, M1 = first mitochondrion, M2 = second mitochondrion, N = nucleus, Pae1 = posterior extremity of the first axoneme, Pae2 = posterior extremity of the second axoneme, Pm = plasma membrane, Pse = posterior spermatozoon extremity, Sb = spine-like body.