Longitudinal sections of spermatozoa of P. shantungensis. A, B Spermatozoa, showing acrosome (a), nucleus (N), arrow indicates connection area between acrosome and nucleus C nucleus-flagellum transition, showing nucleus (N), mitochondrial derivatives (md), accessory body (ab), axoneme (ax), arrow indicates centriole, triangular arrowhead indicates centriolar adjunct D, E flagella of sperm, showing axoneme (ax), mitochondrial derivatives (md) and cristae (arrow). Scale bars: 2 µm (A); 0.5 µm (B, D); 0.1 µm (C, E).