Scanning electron microscopy observation of Rhynchospio aciliata sp. nov., paratype (NIBRIV0000893850) A dorsal view of anterior end with right branchiae removed, nuchal organs (arrowheads) B lateral view of anterior end, first notopodial postchaetal lamellae (arrowheads) C double-paired ciliary bands on right side of chaetiger 41 D pygidium, lateral view E neuropodium of chaetiger 22, ventrolateral view F neuropodial hooded hooks from chaetiger 45, lateral view. nu: metameric nuchal organs, tcb: transverse ciliated bands, itc: intersegmental transverse cilia, pr: prechaetal lobe, po: postchaetal lobe, sa: ventral sabre chaetae. Scale bars: 0.2 mm (A, B); 20 μm (C, F); 0.1 mm (E); 4 μm (G).